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Top 10 Indianapolis 500 Driver Peeves

10. Radio loses FM signal in fourth turn.

9. You crash going 200 mph and you end up in a Marv Albert blooper reel.

8. Suction cup Garfield blocks view of track.

7. Going fast is scary!

6. Having to take a leak with 100 laps left.

5. Forgetting to remove "the Club" before the race starts.

4. When the tape player eats your "Chorus Line" cassette before you've even gone 50 laps.

3. People who pronounce it "Grand Prix."

2. When wife says you lack viscosity.

1. Potholes.

Top 10 Indianapolis 500 Pit Crew Pet Peeves

10. Drivers who want a free NFL mug with every fill-up.

9. Being played in the movies by Jim Nabors.

8. Racers in such a hurry to get out of pit they run over your origami birds.

7. For the rest of your life, any time you're in a car that gets a flat, everyone just assumes that you should fix it.

6. They keep blacking out the good parts of the Rob Lowe video.

5. It's hard to pick up chicks while reeking of methane.

4. The way those suction-cup Garfield dolls fall off at 230 miles per hour.

3. Joke T-shirts that say "Pit Crew Guys Do It in Seven Seconds".

2. Really big dogs who get themselves booked on TV shows and then don't show up.

1. Those pansies at Jiffy-Lube.

Top 10 Perks of Winning the Indianapolis 500

10. Getting showered with 10W-40 in victory lane celebration.

9. Honorary New York City taxi license.

8. Right to represent Earth in Pan-Galactic Monster Truck Rally.

7. Invitation to start Mr. Gotti's car for him.

6. Good chance of meeting Kamaar the Magician backstage at Letterman show.

5. Don't have to shut off lights and lock up speedway like guy who finishes last.

4. Get to throw one free punch at Mr. Goodwrench.

3. Offers of employment from Domino's Pizza.

2. Trophy, bouquet of roses, and a big, wet kiss from Jim Nabors.

1. All the Valvoline a guy can drink.

Auto Parts

Auto parts are components of automobiles. They mainly are, in alphabetic order (only car specific articles or articles with car section):

Air filter

Automotive air filter clogged with dust and debris.An air filter is a device which removes contaminants, often solid particulates such as dust, pollen, mold, and bacteria from air. Air filters are used in application where air quality is important, notably in building ventilation systems and in engines, such as internal combustion engines, gas compressors, diving air compressors, gas turbines and others.

Some buildings, as well as aircraft and other man-made environments (e.g., satellites and space shuttles) use foam, pleated paper, or spun fiberglass filter elements. Another method uses fibers or elements with a static electric charge, which attract dust particles. The air intakes of internal combustion engines and compressors tend to use either paper, foam, or cotton filters. Oil bath filters have fallen out of favor. The technology of air intake filters of gas turbines has improved significantly in recent years, due to improvements in the aerodynamics and fluid-dynamics of the air-compressor part of the Gas Turbines.

Air filter Air Condition / Heater Filter

Air filter Changing Air Filters

Energy Star advises air filters be checked every month, especially during heavy use months (winter and summer). If the filter looks dirty after a month, it should be changed. The air filter should be changed at least every 3 months. A dirty filter will slow down air flow and make the system work harder and use more energy to warm or cool. Improper air flow can cause air conditioning components to freeze. A clean filter will also prevent dust and dirt from building up in the system which can lead to expensive maintenance and/or early system failure.

Air filter Climate control air filters

There are four main types of mechanical air filter media: paper, foam, synthetics, and cotton.

Air filters are found in most all forced-air heating, ventilation, and air conditioning systems. The efficacy of the air filters in such systems significantly affects the Indoor Air Quality. The United States Department of Energy advises that "Air Filtration should have a Minimum Efficiency Reporting Value (MERV) of 13 as determined by ASHRAE 5.2.2-1999." There are a variety of different types of HVAC filters available. Many are inexpensive and not very efficient. Some options are panel, pleated, electrostatic, HEPA, electronic and media. ASHRAE recommends (MERV 6 or higher) air filters to lower the amounts of pollen, mold and dust that reaches the wet evaporator coils in air conditioning systems. Wet coils contaminated with high levels of pollen and dust can allow mold colonies to grow.

Polyester and/or glass fibres are commonly used to make web formations used for air filtration. Both materials have high temperature ratings of at least 120°C (250°F), and are widely used in commercial, industrial and residential applications. Polyester and glass fibres can be blended with cotton or other fibres to produce a wide range of performance characteristics. In some cases Polypropylene, which has a lower temperature tolerance, is used to enhance chemical resistance. Tiny synthetic fibres known as microfibres are used in many types of HEPA (High Efficiency Particulate Air) filters.

Many in-duct filters for home forced air heating and air conditioning systems are made from plain, loosely-spun fiberglass. These filters are inexpensive, disposable, and come in various densities and sizes. Less-dense filters allow for higher airflow, but do not remove as much dust. Higher density filters remove more particles, but are more expensive and offer more resistance to the air. They also become more quickly "loaded" with contaminants and dust.

Air filter Automotive cabin air filters

The cabin air filter is typically a pleated-paper filter that is placed in the outside-air intake for the vehicle's passenger compartment. Some of these filters are rectangular and similar in shape to the combustion air filter. Others are uniquely shaped to fit the available space of particular vehicles' outside-air intakes. Being a relatively recent addition to automobile equipment, this filter is often overlooked and clogged or dirty cabin air filters can significantly reduce airflow from the cabin vents, as well as introduce allergens into the cabin air stream.

Air filter Internal combustion air filters

The combustion air filter prevents abrasive particulate matter from entering the engine's cylinders, where it would cause mechanical wear and oil contamination.

Most modern, fuel-injected vehicles use a pleated paper filter element in the form of a flat panel. This filter is usually placed inside a plastic box connected to the throttle body with a large pipe.

Older vehicles that use carburetors or throttle body fuel injection typically use a cylindrical air filter, usually a few inches high and between 6 and 16 inches in diameter. This is positioned above the carburetor or throttle body, usually in a metal or plastic container which may incorporate ducting to provide cool and/or warm inlet air, and secured with a metal or plastic lid.

Air filter Paper

Pleated paper filter elements are the nearly exclusive choice for automobile engine air cleaners, because they are efficient, easy to service, and cost-effective. The "paper" term is somewhat misleading, as the filter media are considerably different from papers used for writing or packaging, etc. There is a persistent belief amongst tuners, fomented by advertising for aftermarket non-paper replacement filters, that paper filters flow poorly and thus restrict engine performance. In fact, as long as a pleated-paper filter is sized appropriately for the airflow volumes encountered in a particular application, such filters present only trivial restriction to flow until the filter has become significantly clogged with dirt.

Air filter Foam

Oil-wetted polyurethane foam elements are used in some aftermarket replacement automobile air filters. Foam was in the past widely used in air cleaners on small engines on lawnmowers and other power equipment, but automotive-type paper filter elements have largely supplanted oil-wetted foam in these applications. Depending on the grade and thickness of foam employed, an oil-wetted foam filter element can offer minimal airflow restriction or very high dirt capacity, the latter property making foam filters a popular choice in off-road rallying and other motorsport applications where high levels of dust will be encountered.

Air filter Cotton

Cotton gauze is employed in a small number of aftermarket automotive air filters marketed as high-performance items. In the past, cotton gauze saw limited use in original-equipment automotive air filters.

Air filter Oil Bath

An oil bath air cleaner consists of a round base bowl containing a pool of oil, and a round insert which is filled with fibre, mesh, foam, or another coarse filter media. When the cleaner is assembled, the media-containing body of the insert sits a short distance above the surface of the oil pool. The rim of the insert overlaps the rim of the base bowl. This arrangement forms a labyrinthine path through which the air must travel in a series of U-turns: up through the gap between the rims of the insert and the base bowl, down through the gap between the outer wall of the insert and the inner wall of the base bowl, and up through the filter media in the body of the insert. This U-turn takes the air at high velocity across the surface of the oil pool. Larger and heavier dust and dirt particles in the air cannot make the turn due to their inertia, so they fall into the oil and settle to the bottom of the base bowl. Lighter and smaller particles are trapped by the filtration media in the insert, which is wetted by oil droplets aspirated thereinto by normal airflow.

Oil bath air cleaners were very widely used in automotive and small-engine applications until the widespread industry adoption of the paper filter in the early 1960s. Such cleaners are still used in off-road equipment where very high levels of dust are encountered, for oil bath air cleaners can sequester a great deal of dirt relative to their overall size, without loss of filtration efficacy or airflow. However, the liquid oil makes cleaning and servicing such air cleaners messy and inconvenient, they must be relatively large to avoid excessive restriction at high airflow rates, and they tend to increase exhaust emissions of unburned hydrocarbons due to oil aspiration when used on spark-ignition engines.

Automobile self starter

1920's era self-starter.An automobile self-starter (commonly "starter motor" or simply "starter") is an electric motor that initiates piston motion in a car's internal combustion engine before it can power itself.

Automobile self starter History

Both Otto cycle and Diesel cycle internal-combustion engines require the pistons to be moving before the ignition phase of the cycle. This means that the engine must be set in motion by an external force before it can power itself. Originally, a hand crank was used to start engines, but it was inconvenient and rather hard work to crank the engine up to speed. It was also highly dangerous.

Even though cranks had an overrun mechanism to prevent it, when the engine started, the crank could begin to spin along with the crankshaft. Additionally, care had to be taken to retard the spark in order to prevent backfiring: with wrong settings, the engine could kick back (run in reverse), pulling the crank with it, because the overrun safety mechanism works in one direction only.

Although users were advised to cup their fingers under the crank and pull up, it felt natural for operators to grasp the handle with the fingers on one side, the thumb on the other. Even a simple backfire could result in a broken thumb; it was possible to end up with a broken wrist, or worse. Moreover, increasingly larger engines with higher compression ratios made hand cranking a more physically demanding endeavor.

While the need was fairly obvious as early as 1899, Clyde J. Coleman applied for U.S. Patent 745,157 for an electric automobile self-starter inventing one that actually worked waited until 1911 when Charles F. Kettering of Dayton Electric Laboratories (DELCO) invented and filed for U.S. Patent 1,150,523 for the first useful electric starter. The starters were first installed by Cadillac on production models in 1912. These starters also worked as generators once the engine was running, a concept that is now being revived in hybrid vehicles. By 1920, most manufacturers included self-starters.

Automobile self starter Electric starter

The modern starter motor is either a permanent-magnet or a series- or series-parallel wound direct current electric motor with a solenoid switch (similar to a relay) mounted on it. When current from the starting battery is applied to the solenoid, usually through a key-operated switch, it pushes out the drive pinion on the starter driveshaft and meshes the pinion with the ring gear on the flywheel of the engine.

The solenoid also closes high-current contacts for the starter motor, which begins to turn. Once the engine starts, the key-operated switch is opened, a spring in the solenoid assembly pulls the pinion gear away from the ring gear, and the starter motor stops. The starter's pinion is clutched to its driveshaft through an overrunning sprag clutch which permits the pinion to transmit drive in only one direction. In this manner, drive is transmitted through the pinion to the flywheel ring gear, but if the pinion remains engaged (as for example because the operator fails to release the key as soon as the engine starts), the pinion will spin independently of its driveshaft. This prevents the engine driving the starter, for such backdrive would cause the starter to spin so fast as to fly apart.

This overrunning-clutch pinion arrangement was phased into use beginning in the early 1960s; prior to that time, a Bendix drive was used. The Bendix system places the starter drive pinion on a helically-cut driveshaft. When the starter motor begins turning, the inertia of the drive pinion assembly causes it to ride forward on the helix and thus engage with the ring gear. When the engine starts, backdrive from the ring gear causes the drive pinion to exceed the rotative speed of the starter, at which point the drive pinion is forced back down the helical shaft and thus out of mesh with the ring gear.

An intermediate development between the Bendix drive developed in the 1930s and the overrunning-clutch designs introduced in the 1960s was the Bendix Folo-Thru drive. The standard Bendix drive would disengage from the ring gear as soon as the engine fired, even if it did not continue to run. The Folo-Thru drive contains a latching mechanism and a set of flyweights in the body of the drive unit. When the starter motor begins turning and the drive unit is forced forward on the helical shaft by inertia, it is latched into the engaged position. Only once the drive unit is spun at a speed higher than that attained by the starter motor itself (i.e., it is backdriven by the running engine) will the flyweights pull radially outward, releasing the latch and permitting the overdriven drive unit to be spun out of engagement. In this manner, unwanted starter disengagement is avoided prior to a successful engine start.

Automobile self starter Gear-reduction starters

Chrysler Corporation contributed materially to the modern development of the starter motor. In 1962, Chrysler introduced a starter incorporating a geartrain between the motor and the driveshaft. Rolls Royce had introduced a conceptually similar starter in 1946, but Chrysler's was the first volume-production unit. The motor shaft has integrally-cut gear teeth forming a drive gear which mesh with a larger adjacent driven gear to provide a gear reduction ratio of 3.75:1. This permits the use of a higher-speed, lower-current, lighter and more compact motor assembly while increasing cranking torque. Variants of this starter design were used on most vehicles produced by Chrysler Corporation from 1962 through 1987. The Chrysler starter made a unique, readily identifiable sound when cranking the engine.

Hear a Chrysler gear-reduction starter at work

Problems listening to the file? See media help.

This starter formed the design basis for the offset gear reduction starters now employed by about half the vehicles on the road, and the conceptual basis for virtually all of them. Many Japanese automakers phased in gear reduction starters in the 1970's and 1980's. Light aircraft engines also made extensive use of this kind of starter, because its light weight offered an advantage. Those starters not employing offset geartrains like the Chrysler unit generally employ planetary epicyclic geartrains instead. Direct-drive starters are almost entirely obsolete due to their larger size, heavier weight and higher current requirements. Ford also issued a nonstandard starter, a direct-drive "movable pole shoe" design that provided cost reduction rather than electrical or mechanical benefits. This type of starter eliminated the solenoid, replacing it with a movable pole shoe and a separate starter relay. The Ford starter operated as follows:

The operator closed the key-operated starting switch.

A small electric current flowed through the starter relay coil, closing the contacts and sending a large current to the starter motor assembly.

One of the pole shoes, hinged at the front, linked to the starter drive, and spring-loaded away from its normal operating position, swung into position. This moved a pinion gear to engage the flywheel ring gear, and simultaneously closed a pair of heavy-duty contacts supplying current to the starter motor winding. The starter motor cranked the engine until it started. An overrunning clutch in the pinion gear uncoupled the gear from the ring gear.

The operator released the key-operated starting switch, cutting power to the starter motor assembly. A spring retracted the pole shoe, and with it, the pinion gear.

This starter was used on Ford vehicles from 1975 through 1990, when a gear-reduction unit conceptually similar to the Chrysler unit replaced it.

Automobile self starter Pneumatic starter

Some gas turbine engines and Diesel engines, particularly on trucks, use a pneumatic self-starter. The system consists of a geared turbine, an air compressor and a pressure tank. Compressed air released from the tank is used to spin the turbine, and through a set of reduction gears, engages the ring gear on the flywheel, much like an electric starter would. The engine, once running, powers the compressor to recharge the tank.

Another method, for large diesel engines, uses additional valves in cylinder heads. Compressed air is let in the cylinders so that its pressure pushes pistons down when appropriate; at the upward piston movement, air is discharged through normal exhaust valves.

Since large trucks typically use air brakes, the system does double duty, supplying compressed air to the brake system. Pneumatic starters have the advantages of delivering high torque, mechanical simplicity and reliability. They eliminate the need for oversized, heavy storage batteries in prime mover electrical systems.

Automobile self starter Auxiliary starter engine

A large, high power Diesel engine, such as those used in off-road heavy equipment, may have a small gasoline-powered engine attached to the side as a starter.

These were also sometimes called pony engines. On some applications, they shared the same cooling system and oil supply. As the pony engine warmed up, it circulated warm coolant and warm oil in the diesel engine. In addition to making it easier to crank, it improved the service life.

Automobile self starter Static-start engine

Another way to provide for shutting off a car's engine when it is stopped, then immediately restarting it when it's time to go, is by employing a static-start engine. Such an engine requires no starter motor, but employs sensors to determine the exact position of each piston, then precisely timing the injection and ignition of fuel to turn over the engine.

Bell housing

The bell housing is part of the transmission system on a gasoline (also known as petrol) or diesel powered vehicle. It is bolted to the engine block and contains the flywheel and the torque converter or clutch of the transmission. The starter motor is usually mounted here engaging with a ring gear on the flywheel. On the opposite end to the engine is usually bolted the gearbox.

The above is the normal arrangement for an in line transmission system for a conventional rear wheel drive or all wheel drive vehicle. The arrangement for a transverse mounted engine and transmission for a front wheel drive vehicle has the gear box and differential below the engine and consequently the bell housing is a simple cover for the flywheel.

A bare Buick, Olds, Pontiac pattern bellhousing viewed from the engine endBell housings take their name from their shape rather than their function. To the technically literate they are better-known as clutch housings or torque converter housings, depending on what they actually house.

Brake

Disc brake on a motorcycle.A brake is a device for slowing or stopping the motion of a machine or vehicle, or alternatively a device to restrain it from starting to move again. The kinetic energy lost by the moving part is usually translated to heat by friction. Alternatively, in regenerative braking, much of the energy is recovered and stored in a flywheel, capacitor or turned into alternating current by an alternator, then rectified and stored in a battery for later use.

Note that kinetic energy increases with the square of the velocity (E = ½m·v2 relationship). This means that if the speed of a vehicle doubles, it has four times as much energy. The brakes must therefore dissipate four times as much energy to stop it and consequently the braking distance is four times as long.

Brakes of some description are fitted to most wheeled vehicles, including automobiles of all kinds, trucks, trains, motorcycles, and bicycles. Baggage carts and shopping carts may have them for use on a moving ramp.

Some aeroplanes are fitted with wheel brakes on the undercarriage. Some aircraft also feature air brakes designed to slow them down in flight. Notable examples include gliders and some WWII-era fighter aircraft. These allow the aircraft to maintain a safe speed in a steep descent. The Saab B 17 dive bomber used the deployed undercarriage as an air brake.

Deceleration and avoiding acceleration when going downhill can also be achieved by using a low gear; see engine braking.

Friction brakes on cars store the heat in the rotating part (drum brake or disc brake) during the brake application and release it to the air gradually.

Brake Effects on noise pollution

The action of braking for motor vehicles produces recognizable sound level emissions, varying with the specific tire types and with the roadway surface type produces considerable effect upon sound levels or noise pollution emanating from moving vehicles. There is a considerable range in acoustical intensities produced depending upon the specific tire tread design and the rapidity of deceleration required to slow the vehicle.

Bucket seat

Bucket seats in a 1968 Saab Sonett mk2 V4.A bucket seat is a seat contoured to hold one person, distinct from bench seats which are flat platforms designed to seat multiple people. Bucket seats are standard in fast cars to keep riders in place when making sharp or quick turns.

The term appears to come from the French word, baquet, meaning "cockpit". Bucket seats resemble seats that were used in the cockpits of early aircraft, and are still used today in single-pilot aircraft.

Racing vehicles usually have only one bucket seat. Vehicles sold to the general public often have two bucket seats in the front compartment, and may contain more in a rear compartment. Commercial aircraft now have bucket seats for all passengers.

Automobile bucket seats first came into use after World War II on European small cars, due to:

their relatively small size compared to a bench seat; and lack of seating room for a middle passenger, due to the presence of a floor-mounted shifter and parking brake lever. The bucket seat trend was especially apparent in sporty cars, particularly two-seater sports cars, most of which were manufactured in European nations.

For decades, American cars were typically equipped with bench seats, which permitted three-passenger seating. The advent of compact cars and specialty vehicles such as the Ford Thunderbird in the late 1950s and early 1960s, and sporty versions of both standard-sized and compact cars, accelerated the bucket-seat trend in domestic cars around 1960.

By 1962, more than a million U.S. built cars were factory equipped with bucket seats, which were then further popularized with the advent of sporty compact cars, often dubbed "ponycars", such as the Ford Mustang.

In later decades, as U.S. cars were designed smaller in order to meet increasingly stringent fuel economy standards as well as intense competition from imported cars (particularly Japanese models), bucket seats became more common in domestic cars with each passing year. The once-standard bench seat is now generally relegated to a few larger sedans and pickup trucks.

Bumper

The bumper of a BMW M5, highlighted in redA bumper is a part of an automobile designed to allow one vehicle to impact with another and to withstand that collision without severe damage to the vehicle's frame. Brush guards, push bars, etc. were added "after-market" to bumpers of automobiles, pickups, trucks, and utility vehicles since at least the 1920s to provide additional protection to the vehicle. While bumpers were originally made of heavy steel, in later years they have been constructed of rubber, plastic, or painted light metal leaving them susceptible to damage from even minimal contact. For the most part, these vehicles cannot push, or be pushed by, another vehicle. An entire after-market industry has developed which now produces various guards to protect these vulnerable modern bumpers.

The fun of bumping one car into another led to the creation of bumper cars at amusement parks and carnivals. These small cars are designed to fit one or at most two people and crashed into each other consistently.

Bumper History

Early bumpers were little more than a strap or flat iron. They later swelled out to chromed bumpers, especially in the 1960s. In the early 1970s self repairing bumpers were introduced and after a while they became mandatory (thus killing the Opel GT). Towards the end of the 1980s self repairing bumpers went out of style and were replaced with fibreglass "bumpers" that cracked at impact.

Bumper Reliability

Bumper laws had been rolled back in 1982, reducing the reliability of bumpers in newer cars to sustain damage. Minor collisions may already ruin the aesthetic appearance (paint and finish) of bumpers, and cracked bumpers can only be replaced entirely, resulting in hefty repair costs even for minor collisions.

Bumper Legal issues

In many jurisdictions, bumpers are legally required on all vehicles for safety reasons. The height and placement of bumpers may be legally specified as well, to ensure that when vehicles of different heights are in an accident, that the smaller vehicle will not slide under the larger vehicle, particularly in collisions with semi-trailer trucks.

Buzzer

Electronic symbol for a buzzer

Metal disk with piezoelectric disk attached, as found in a buzzerFor the woodworking machine, see jointer. A buzzer or beeper is a signaling device, usually electronic, typically used in automobiles, household appliances such as a microwave oven, or game shows.

It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed, and usually illuminates a light on the appropriate button or control panel, and sounds a warning in the form of a continuous or intermittent buzzing or beeping sound. Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise). Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board. Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker. Nowadays, it is more popular to use a ceramic-based piezoelectric sounder like a Sonalert which makes a high-pitched tone. Usually these were hooked up to "driver" circuits which varied the pitch of the sound or pulsed the sound on and off.

In game shows it is also known as a "lockout system," because when one person signals ("buzzes in"), all others are locked out from signalling. Several game shows have large buzzer buttons which are identified as "plungers".

The word "buzzer" comes from the rasping noise that buzzers made when they were electromechanical devices, operated from stepped-down AC line voltage at 50 or 60 cycles. Other sounds commonly used to indicate that a button has been pressed are a ring or a beep.

Some systems, such as the one used on Jeopardy!, make no noise at all, instead using light. Another example is the buzzer at the end of each stage in Sasuke, Kunoichi, and Viking. These buzzers do not make a sound or turn on a light; instead, they stop a nearby digital clock, briefly fire two smoke cannons on each side of the stage exit, and open the exit. However, at the end of the Heartbreaker in Viking, the buzzer is replaced with a sword that, when removed, causes two contacts to touch, closing the circuit and causing the latter two actions above to occur.

Nowadays some people use the word "buzzer" as to describe a person who's able to create a big buzz around a brand, an event or a company.

Car battery

Lead-acid car batteryA car battery is a type of rechargeable battery that supplies electric energy to an automobile. Usually this refers to a SLI battery (Starting - Lighting - Ignition) to power the starter motor, the lights, and the ignition system of a vehicle’s engine. This also may describe a traction battery used for the main power source of an electric vehicle.

Automotive starter batteries (usually of lead-acid type) provide a nominal 12-volt potential difference by connecting six galvanic cells in series. Since the cells naturally produce about 2.1 V, the actual voltage is roughly 12.6 V. Lead-acid batteries are made up of plates of lead and lead oxide, which are submerged into an electrolyte solution of 35% sulfuric acid and 65% water. This causes a chemical reaction that releases electrons, allowing them to flow through conductors to produce electricity. As the battery discharges, the acid of the electrolyte reacts with the materials of the plates, changing their surface to lead sulphate. When the battery is recharged, the chemical reaction is reversed: the lead sulphate reforms into lead oxide and lead. With the plates restored to their original condition, the process may now be repeated.

Car battery Types

Lead-acid batteries have different uses. Several elements are alloyed with the lead such as calcium, cadmium or strontium to change density, hardness, or porosity of the plates and to make the plates easier to manufacture.

The starting (cranking) or shallow cycle type is designed to deliver quick bursts of energy, usually to start an engine. They usually have a greater plate count in order to have a larger surface area that provides high electric current for short period of time. Once the engine is started, they are continuously recharged. See Jump start (vehicle). The deep cycle (or motive) type is designed to continuously provide power for long periods of time (for example in a trolling motor for a small boat, a golf cart or other battery electric vehicle). They can also be used to store energy from a photovoltaic array or a small wind turbine. They usually have thicker plates in order to have a greater capacity and survive a higher number of charge/discharge cycles. See battery pack.

Some batteries are claimed by their manufacturers to be dual purpose (starting and deep cycling).

Car battery Use and maintenance

Car battery Fluid level

Formerly car batteries using lead-antimony plates would require regular top-up to replace water lost due to electrolysis on each charging cycle. By changing the alloying element, more recent designs have lower water loss unless overcharged. Modern car batteries have low maintenance requirements, and may not provide caps for addition of water to the cells. If the battery has easily detachable caps then a top up may be required from time to time. Prolonged overcharging or charging at excessively high voltage causes some of the water in the electrolyte to be broken up into hydrogen and oxygen gases, which escape from the cells. If the electrolyte liquid level drops too low, the plates are exposed to air, lose capacity and are damaged. The cells can be topped up with distilled or deionised water just above the visible plates. The sulphuric acid in the battery normally does not require replacement since it is not consumed even on overcharging.

Impurities in the water will reduce the life and performance of the battery. Manufacturers usually recommend use of demineralized or distilled water since even potable tap water can contain high levels of minerals.

Car battery Charge and discharge

In normal automotive service the vehicle's engine-driven alternator powers the vehicle's electrical systems and restores charge used from the battery during engine cranking. When installing a new battery or recharging a battery that has been accidentally discharged completely, one of several different methods can be used to charge it. The most gentle of these is called trickle charging. Other methods include slow-charging and quick-charging, the latter being the harshest.

In emergencies a battery can be jump started, by the battery of another vehicle or by a hand portable battery booster.

Car battery Changing a battery

In most modern automobiles, the grounding is provided by connecting the body of the car to the negative electrode of the battery, a system called 'negative ground'. In the past some cars had 'positive ground'. Such vehicles were found to suffer worse body corrosion and, sometimes, blocked radiators due to deposition of metal sludge.

The recommended practice when removing a car battery is to disconnect the ground connection first and then other terminal. This ensures that a short circuit will not occur by a wrench touching grounded engine parts while disconnecting the other terminal. Similarly, the ground should be connected last when installing a battery.

Care should be taken when first filling the battery with acid, as acids are highly corrosive and can damage eyes, skin and mucous membranes. A 1994 study by the National Highway Traffic Safety Association estimated that in 1994 more than 2000 people were injured in the United States while working with automobile batteries.

Car battery Freshness

Because of "sulfation" (see lead-acid battery), lead-acid batteries stored with electrolyte slowly deteriorate. Car batteries should be installed within one year of manufacture. In the United States, the manufacturing date is printed on a sticker. The date can be written in plain text or using an alphanumerical code. The first character is a letter that specifies the month (A for January, B for February and so on). The letter "I" is skipped due to its potential to be mistaken for the number 1. The second character is a single digit that indicates the year of manufacturing (for example, 6 for 2006).

Car battery Corrosion

Corrosion at the battery terminals can prevent a car from starting. To prevent corrosion, during regular battery service the terminals may be cleaned with a wire brush and corrosion products washed away with water. When the battery terminals are re-assembled, they are coated with vaseline/petrolium jelly (grease is not desired) to reduce the rate of corrosion accumulation.

Car battery Battery defects

Common battery faults include:

Shorted cell due to failure of the separator between the positive and negative plates

Broken internal connections due to corrosion

Broken plates due to vibration and corrosion

Low electrolyte

Cracked or broken case

Broken terminals

Sulfation after prolonged disuse.

In addition, the primary wear-out mechanism is the shedding of active material from the battery plates, which accumulates at the bottom of the cells and which may eventually short-circuit the plates.

Early automotive batteries could sometimes be repaired by dismantling and replacing damaged separators, plates, intercell connectors, and other repairs. Modern battery cases do not facilitate such repairs; an internal fault generally requires replacement of the entire unit.

Car battery Exploding batteries

Any lead-acid battery system when overcharged will produce hydrogen gas. If the rate of overcharge is small, the vents of each cell allow the dissipation of the gas. However, on severe overcharge or if ventilation is inadequate, a flammable concentration of hydrogen may remain in the cell or in the battery enclosure. Any spark can cause an explosion, which will damage the battery and its surroundings and which will disperse acid into the surroundings. Car batteries should always be handled with proper protective equipment (goggles, overalls, gloves).

Car battery Terms and ratings

Ampere-hours (A·h) is the product of the time that a battery can deliver a certain amount of current (in hours) times that current (in amps), for a particular discharge period. This is one indication of the total amount of charge a battery is able to store and deliver at its rated voltage. This rating is rarely stated for automotive batteries.

Cranking amps (CA), also sometimes referred to as marine cranking amps (MCA), is the amount of current a battery can provide at 32°F (0°C). The rating is defined as the number of amperes a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12 volt battery).

Cold cranking amps (CCA) is the amount of current a battery can provide at 0°F (-18°C). The rating is defined as the amperage a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery). It is a more demanding test than those at higher temperatures.

Hot cranking amps (HCA) is the amount of current a battery can provide at 80°F (26.7°C). The rating is defined as the amperage a lead-acid battery at that temperature can deliver for 30 seconds and maintain at least 1.2 volts per cell (7.2 volts for a 12-volt battery).

Reserve capacity minutes (RCM), also referred to as reserve capacity (RC), is a battery's ability to sustain a minimum stated electrical load; it is defined as the time (in minutes) that a lead-acid battery at 80°F (27°C) will continuously deliver 25 amperes before its voltage drops below 10.5 volts.

Battery Council International group size (BCI) specifies a battery's physical dimensions, such as length, width, and height. These groups determined are by the Battery Council International organization. Peukert's Law expresses the fact that the capacity available from a battery varies according to how rapidly it is discharged. A battery discharged at high rate will give fewer amperehours than one discharged more slowly. The hydrometer measures the density, and therefore indirectly the amount of sulfuric acid in the electrolyte. A low reading means that sulfate is bound to the battery plates and that the battery is discharged. Upon recharge of the battery, the sulfate returns to the electrolyte.

The open circuit voltage, measured when the engine is off. It can be approximately related to the charge of the battery by: Open Circuit Voltage (12V) Open Circuit Voltage (6V) Approximate charge Relative acid density Open circuit voltage is also affected by temperature, and the specific gravity of the electrolyte at full charge.

Car battery Lead-acid

The following is common for lead-acid batteries:

Quiescent (open-circuit) voltage at full

charge: 12.6 V

Unloading-end: 11.8 V

Charge with 13.2-14.4 V

Gassing voltage: 14.4 V

Continuous-preservation charge with max. 13.2 V

After full charge the terminal voltage will drop quickly to 13.2 V and then slowly to 12.6 V. The energy to weight ratio, or specific energy, is in the range of 30 Wh/kg (108 kJ/kg).

Car battery Formats

Lead-acid battery The most commonly used battery for SLI applications. It has a low specific energy, but is cheaper than high-performance battery types.

Car battery Future Trends

Due to the increase of electric power payloads in today’s automobile, a 42 V power system has been considered and is being developed to replace the existing 14 V power system. (14 V and 42 V refer to the alternator charging voltage). See for example Modeling of 36 V Lead Acid Battery for the 42 V Automotive System Simulation. For 42 V systems, 18 cell lead acid battery with a nominal 36 V is proposed.

Car Catalytic converter

Catalytic converter on a Saab 9-5.A catalytic converter (colloquially, "cat" or "catcon") is a device used to reduce the toxicity of emissions from an internal combustion engine. First widely introduced on series-production automobiles in the US market for the 1975 model year to comply with tightening EPA regulations on auto exhaust, catalytic converters are still most commonly used in motor vehicle exhaust systems. Catalytic converters are also used on generator sets, forklifts, mining equipment, trucks, buses, trains, and other engine-equipped machines. A catalytic converter provides an environment for a chemical reaction wherein toxic combustion by-products are converted to less-toxic substances.

Car Catalytic converter Functions

Car Catalytic converter Three-way catalytic converters

A three-way catalytic converter has three simultaneous tasks:

Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx ? xO2 + N2

Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 ? 2CO2

Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: 2CxHy + (2x+y/2)O2 ? 2xCO2 + yH2O These three reactions occur most efficiently when the catalytic converter receives exhaust from an engine running slightly above the stoichiometric point. This is between 14.8 and 14.9 parts air to 1 part fuel, by weight, for gasoline (the ratio for LPG, natural gas and ethanol fuels is slightly different, requiring modified fuel system settings when using those fuels). When there is more oxygen than required, then the system is said to be running lean, and the system is in oxidizing condition. In that case, the converter's two oxidizing reactions (oxidation of CO and hydrocarbons) are favoured, at the expense of the reducing reaction. When there is excessive fuel, then the engine is running rich. The reduction of NOx is favoured, at the expense of CO and HC oxidation. If an engine could be operated with infinitesimally small oscillations about the stoichiometric point for the fuel used, it is theoretically possible to reach 100% conversion efficiencies.

Since 1981, three-way catalytic converters have been at the heart of vehicle emission control systems in North American roadgoing vehicles, and have been used on "large spark ignition" (LSI) engines since 2001 in California, and from 2004 in the other 49 states. LSI engines are used in forklifts, aerial boom lifts, ice resurfacing machines and construction equipment. The converters used in those types of machines are three-way types, and are designed to reduce combined NOx+HC emissions from 12 gram/BHP-hour to 3 gram/BHP-hour or less, as mandated by the United States Environmental Protection Agency's (EPA) 2004 regulations.

A further drop to 2 gram/BHP-hour of NOx+HC emissions is mandated in 2007 (note: NOx is the industry standard short form for nitric oxide (NO) and nitrogen dioxide (NO2) both of which are smog precursors. HC is the industry short form for hydrocarbons). The EPA intends to introduce emissions rules for stationary spark ignition engines, to take effect in January 2008.

Car Catalytic converter Two-way catalytic converters

A two-way catalytic converter has two simultaneous tasks:

Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 ? 2CO2

Oxidation of unburnt hydrocarbons (unburnt and partially-burnt fuel) to carbon dioxide and water: 2CxHy + (2x+y/2)O2 ? 2xCO2 + yH2O This type of catalytic converter is widely used on diesel engines to reduce hydrocarbon and carbon monoxide emissions. They were also used on spark ignition (gasoline) engines in USA market automobiles up until 1981, when they were replaced by three-way converters due to regulatory changes requiring reductions on NOx emissions.

Reduction of the NOx emissions requires an additional step. Platinum catalysis can be used. Instead of catalysis, a true reactant diesel fuel or ammonia pyrolyzed in situ from urea can be used to reduce the NOx into nitrogen.

Curiously, the regulations regarding hydrocarbons vary according to the engine regulated, as well as the jurisdiction. In some cases, "non-methane hydrocarbons" are regulated, while in other cases, "total hydrocarbons" are regulated. Technology for one application (to meet a non-methane hydrocarbon standard) may not be suitable for use in an application that has to meet a total hydrocarbon standard. Methane is not toxic, but is more difficult to break down in a catalytic converter, so in effect a "non-methane hydrocarbon" standard can be considered to be looser. Since methane is a greenhouse gas, interest is rising in how to eliminate emissions of it.

Car Catalytic converter Catalyst poisoning and deactivation

Catalytic converters become ineffective in the presence of lead due to catalyst poisoning. Therefore, vehicles equipped with catalytic converters must only be run on unleaded gasoline, and it is this fact, as much as concerns about the possibly harmful effects of lead emissions, which caused the end of pump-available leaded gasoline in countries where catalytic converters have been in common use for many years. Leaded "race only" fuel is still used for non-catalyst vehicles in some countries. Catalyst poisoning occurs when a substance in the engine exhaust coats the surface of the catalyst, preventing further exhaust access to the catalytic materials. Poisoning can sometimes be reversed by running the engine under a very heavy load for an extended period of time to raise exhaust gas temperature, which may cause liquefaction or sublimation of the catalyst poison. Common catalyst poisons are lead, sulfur, zinc, manganese, silicon and phosphorus.

Zinc, phosphorus and sulfur originate from lubricant antiwear additives such as ZDDP; sulfur and manganese primarily originate from fuel impurities or from additives such as Methylcyclopentadienyl Manganese Tricarbonyl (MMT), respectively. Silicon poisoning in automotive applications is the result of engine damage, such as a faulty cylinder head gasket or cracked casting, admitting silicate-containing coolant into the combustion chamber. In stationary engines silicon poisoning is more often caused by the use of methane landfill gas as a fuel.

Removal of sulfur from a catalyst surface by running heated exhaust gases over the catalyst surface is often successful; however, removal of lead deposits in this manner is usually not possible because of lead's high boiling point. In particularly bad cases of catalyst poisoning by lead, the catalytic converter can actually become completely plugged with lead residue.

A variety of conditions may cause the catalyst to overheat (heat deactivation) and potentially to melt down. Some factors that can cause this are:

lubricating oil in the exhaust system (caused by engine wear, or by damaged rings or valves) an engine misfire or ignition failure (causing unburnt fuel to enter the exhaust) a cracked exhaust valve (again, causing unburnt fuel in the exhaust)

Overly rich fuel mixtures are not usually a problem - there is too little unused oxygen for the exothermic reaction to be large enough to cause damage. A slightly leaner than stoichiometric mix is far more dangerous, as the oxygen level is elevated, allowing a very large exotherm, and many engine manufacturers design "rich excursions" as a catalyst protection measure in the engine control software. In the early days of catalyst-equipped cars, (primarily in the USA) before the advent of sophisticated engine management systems, it was necessary for fuel/air mixtures to be significantly richer than had hitherto been the case to allow the catalyst to work effectively. This contributed to the very poor fuel consumption figures achieved by such cars.

Engine misfires can overheat and destroy the converter as the excessive amounts of unburned fuel are broken down within it, especially when the engine is under heavy loads. Vehicles equipped with OBD-II diagnostic systems are designed to alert the driver of a misfire condition, along with other malfunctions, using the Malfunction Indicator Lamp or "Check Engine" light. If the misfire and engine load can produce heating severe enough to cause catalyst damage, the MIL will flash until the misfire or engine load is reduced.

Car Catalytic converter Technical details

The core, or substrate. In modern catalytic converters, this is most often a ceramic honeycomb, however stainless steel foil honeycombs are also used. The purpose of the core is to "support the catalyst" and therefore it is often called a "catalyst support". The ceramic substrate was invented by Rodney Bagley, Irwin Lachman and Ronald Lewis at Corning Glass for which they were inducted into the National Inventors Hall of Fame in 2002. The washcoat. In an effort to make converters more efficient, a washcoat is utilized, most often a mixture of silica and alumina. The washcoat, when added to the core, forms a rough, irregular surface which has a far greater surface area than the flat core surfaces, which is desirable to give the converter core a larger surface area, and therefore more places for active precious metal sites. The catalyst is added to the washcoat (in suspension) before application to the core. The catalyst itself is most often a precious metal. Platinum is the most active catalyst and is widely used. However, it is not suitable for all applications because of unwanted additional reactions and/or cost. Palladium and rhodium are two other precious metals that are used. Platinum and rhodium are used as a reduction catalyst, while platinum and palladium are used as an oxidization catalyst. Cerium, iron, manganese and nickel are also used, though each has its own limitations. Nickel is not legal for use in the European Union (due to reaction with carbon monoxide). While copper can be used, its use is illegal in North America due to the formation of dioxin.

Car Catalytic converter Conventional spark ignition engines

Catalytic converters are used on spark ignition (gasoline; liquified petroleum gas (LPG); flexible fuel vehicles burning varying blends of E85 and gasoline; compressed natural gas (CNG)) engines; and compression ignition (diesel) engines.

For spark ignition engines, the most commonly used catalytic converter is the three-way converter which converts the three main pollutants of concern CO, HC, and NOx to less-toxic substances. The control of NOx involves a reduction process that releases oxygen and the control of CO and HC involves an oxidation process that consumes oxygen. Therefore, a 3-way converter contains two catalyst-coated stages: The first catalyst stage encountered by the exhaust is for reduction of NOx, which produces oxygen employed by the second stage to oxidize CO and HC. 3-way converters work most efficiently with exhaust from engines operated on a stoichiometric air-fuel mixture. Generally, such engines are equipped with closed-loop feedback fuel mixture control employing one or more oxygen (lambda) sensors. While a 3-way catalyst can be used in an open-loop system, NOx reduction efficiency is low. Since NOx emissions are now regulated throughout the world, open-loop fuel systems are obsolete in many jurisdictions. Closed-loop maintenance of the stoichiometric air-fuel ratio is most often attained by means of an engine management system with computer-controlled fuel injection, though early in the deployment of 3-way converters, carburetors equipped for feedback mixture control were used during the transition to fuel injection. Within a narrow ratio band surrounding stoichiometry, conversion of all three pollutants is very complete, sometimes approaching 100%. However, outside of that band, conversion efficiency falls off very rapidly. Two-way (or oxidation) converters act only to control CO and HC, and have therefore been abandoned on conventional spark ignition engines in most jurisdictions due to an inability to control NOx.

A three-way catalyst reduces emissions of CO (carbon monoxide), HC (hydrocarbons), and NOx (nitrogen oxides) simultaneously when the oxygen level of the exhaust gas stream is below 1.0%, though performance is best at below 0.5% O2. Unwanted reactions, such as the formation of H2S (hydrogen sulfide) and NH3 (ammonia), can occur in the three-way catalyst. Formation of each can be limited by modifications to the washcoat and precious metals used. It is, however, difficult to eliminate these side products entirely.

For example, when control of H2S (hydrogen sulfide) emissions is desired, nickel or manganese is added to the washcoat - both substances act to block the adsorption of sulfur by the washcoat. H2S is formed when the washcoat has adsorbed sulfur during a low temperature part of the operating cycle, which is then released during the high temperature part of the cycle and the sulfur combines with HC. For "lean burn" spark ignition engines (e.g. compressed natural gas, or compressed natural gas with diesel fuel pilot injection), an oxidation catalyst is used in the same manner as in a compression ignition engine.

Recently, many systems have used a pre-catalyst in the system to reduce startup emissions and burn off hydrocarbons from the extra-rich mixture used in a cold engine. Upstream and downstream parts are now often separated in the system to provide an optimum temperature and space for extra oxygen sensors. The converter needs to be placed close enough to the engine to quickly reach operating temperature but far enough away to avoid heat damage.

Many three-way catalytic converters utilize an air injection tube between the first (NOx reduction) and second (HC and CO oxidation) biscuits of the converter. This tube is fed by either an air pump or by an aspirator. The injected air provides oxygen for the catalyst's oxidizing reaction. These systems also sometimes include an upstream air injector to admit oxygen to the exhaust system before it reaches the catalytic converter. This precleans the extra-rich exhaust from a cold engine, and helps bring the catalytic converter quickly up to operating temperature.

Most newer systems do not employ air injection. Instead, they provide a constantly varying mixture that quickly and continually cycles between lean and rich to keep the first catalyst (NOx reduction) from becoming oxygen loaded, and to keep the second catalyst (CO oxidization) sufficiently oxygen-saturated. They also utilize several oxygen sensors to monitor the exhaust, at least one before the catalytic converter for each bank of cylinders, and one after the converter. Some systems contain the reduction and oxidation functions separately rather than in a common housing.

Car Catalytic converter Diesel engines

For compression ignition (i.e., Diesel) engines, the most commonly used catalytic converter is the diesel oxidation catalyst. The catalyst uses excess O2 (oxygen) in the exhaust gas stream to oxidize CO (Carbon Monoxide) to CO2 (Carbon Dioxide) and HC (hydrocarbons) to H2O (water) and CO2. These converters often reach 90% effectiveness, virtually eliminating diesel odor and helping to reduce visible particulates (soot), however they are incapable of reducing NOx as chemical reactions always occur in the simplest possible way, and the existing O2 in the exhaust gas stream would react first.

To reduce NOx on a compression ignition engine it is necessary to change the exhaust gas - two main technologies are used for this - selective catalytic reduction (SCR) and NOx (NOx) traps (or NOx Adsorbers).

Another issue for diesel engines is particulate (soot). This can be controlled by a soot trap or diesel particulate filter (DPF), as catalytic converters are unable to affect elemental carbon (however they will remove up to 90% of the soluble organic fraction). A clogging soot filter creates a lot of back pressure decreasing engine performance. However, once clogged, the filter goes through a regeneration cycle where diesel fuel is injected directly into the exhaust stream and the soot is burned off. After the soot has been burned off the regeneration cycle stops and injection of diesel fuel stops. This regeneration cycle should not affect performance of the engine.

All major diesel engine manufacturers in the USA (Ford, Caterpillar, Cummins, Volvo, MMC) starting January 1, 2007 are required to have a catalytic converter and a soot filter inline, as per new EPA legislation. http://www.epa.gov/otaq/highway-diesel/regs/2007-heavy-duty-highway.htm

Car Catalytic converter Oxygen storage in three-way converters

In order to oxidize CO and HC, the catalytic converter also has the capability of storing the oxygen from the exhaust gas stream, usually when the air fuel ratio goes lean. When insufficient oxygen is available from the exhaust stream the stored oxygen is released and consumed. This happens either when oxygen derived from NOx reduction is unavailable or certain maneuvers such as hard acceleration enrich the mixture beyond the ability of the converter to compensate.

Note that diesel catalysts do not use this feature as there is sufficient O2 in the exhaust gas stream to handle the CO & HC reductions needed.

Car Catalytic converter Regulations

Emissions regulations vary considerably from jurisdiction to jurisdiction, as do what engines are regulated. In North America any spark ignition engine of over 19 kW (25 hp) power output built later than January 1, 2004 probably has a three-way catalytic converter installed. In Japan a similar set of regulations came into effect January 1, 2007, while the European Union has not yet enacted analogous regulations. Most automobile spark ignition engines in North America have been fitted with catalytic converters since the mid-1970s and the technology used in non-automotive applications is generally based on automotive technology.

Diesel engine regulations are similarly varied, with some jurisdictions focusing on NOx (Nitric Oxide and Nitrogen Dioxide) emissions and others focusing on particulate (soot) emissions. This can cause problems for the engine manufacturers as it may not be economical to design an engine to meet two sets of regulations.

An important issue is that fuel quality varies widely from place to place, even within jurisdictions, as do the regulations covering fuel quality. In North America, Europe, Japan, and Hong Kong both gasoline and diesel fuel are highly regulated and there are campaigns under way to regulate CNG and LPG as well. In most of Asia and Africa this is not true - in some places sulfur content of the fuel can reach 20,000 parts per million (2%). Any sulfur in the fuel may be oxidized to SO2 (sulfur dioxide) or even SO3 (sulfur trioxide) in the combustion chamber. If sulfur passes over a catalyst it may be further oxidized in the catalyst, i.e. (SO2 may be further oxidized to SO3). Sulfur oxides are precursors to sulfuric acid, a major component of acid rain. While it is possible to add substances like vanadium to the catalyst wash coat to combat sulfur oxide formation, this will reduce the effectiveness of the catalyst the best solution is further refinement of the fuel at the refinery to remove the sulfur. Regulations in Japan, Europe and by 2007 North America tightly restrict the amount of sulfur permitted in motor fuels. However, the expense is such that this is not practical in many developing countries. As a result cities in these countries with high levels of vehicular traffic suffer damage to buildings due to acid rain eating away the stone/woodwork, and acid rain has deleterious effects on the local ecosystem.

Car Catalytic converter Regulatory agencies

The agencies charged with regulating engine emissions vary from jurisdiction to jurisdiction, even in the same country. For example, in the United States, overall responsibility belongs to the United States Environmental Protection Agency (EPA), but due to special requirements of the State of California, emissions in California are regulated by the Air Resources Board. In Texas, the Texas Railroad Commission is responsible for regulating emissions from LPG fueled rich burn engines (but not gasoline fueled rich burn engines).

California Air Resources Board - California, United States (most sources)

Environment Canada - Canada (most sources)

Environmental Protection Agency - United States (most sources)

Texas Railroad Commission - Texas, United States (LPG fueled engines only)

Transport Canada - Canada (trains and ships)

Car Catalytic converter Criticisms

Car Catalytic converter Environmental impact

Catalytic converters have proven to be reliable devices and have been successful in reducing noxious tailpipe emissions. However, they may have some adverse environmental impacts in use:

The requirement for a rich burn engine to run at the stoichiometric point means it uses more fuel than a "lean burn" engine running at a mixture of 20:1 or less. This increases the amount of fossil fuel consumed and the carbon dioxide emissions of the vehicle. However, NOx control on lean burn engines is problematic at best, and many lean burn engine manufacturers are considering rich burn variations.

The manufacturing of catalytic converters requires palladium and/or platinum; a portion of the world supply of these precious metals is produced near the Russian city of Norilsk, with significant negative environmental effects.

Car Catalytic converter theft

Due to the use of precious metals including platinum worth up to $1,200 an ounce; palladium at up to $320 an ounce; and rhodium at up to $6,400 an ounce, catalytic converters are a target for thieves. The problem is especially common among late-model Toyota trucks and SUVs, due to their high ground clearance and easily-removed bolt-on catalytic converters. Welded-in converters are also at risk of theft from SUVs and trucks, as they can be removed within five minutes by means of a battery powered reciprocating saw. The value of precious metals in a single converter is low, seldom over $50 per converter at 2007 prices. UK prices fluctuate between £35-$70 and £45-$90 for genuine converters and approx £8-£16 for non genuine converters being bought as scrap metal.

Car Catalytic converter Diagnostics

Various jurisdictions now legislate on-board diagnostics to monitor the effectiveness of the emissions control system, including the catalytic converter and such diagnostics are often included in aftermarket retrofit kits as a matter of course, even if legislation does not directly require them.

On-board diagnostics take several forms, depending upon the legislation and the type of emissions control product being monitored, the three main types are:

temperature

oxygen

NOx

Car Catalytic converter Temperature sensors

Temperature sensors are used for two purposes. The first is as a warning system, typically on obsolete 2-Way catalytic converters such as are still sometimes used on LPG forklifts. The function of the sensor is to warn of temperature excursions above the safe operating temperature of 750°Celsius of the two-way catalytic converter. Note that modern catalytic converters are not as susceptible to temperature damage with many modern three-way platinum based converters able to handle temperatures of 900°C sustained. Temperature sensors are also used to monitor catalyst functioning - usually two sensors will be fitted, with one before the catalyst and one after to monitor the temperature rise over the catalytic converter core. For every 1% of CO in the exhaust gas stream the exhaust gas temperature will rise by 100°C.

Car Catalytic converter Oxygen sensors

The Oxygen sensor or "lambda sensor" is the basis of the closed loop control system on a spark ignited rich burn engine, however it is also used for diagnostics. Oxygen sensors only work when at operating temperature, when they output a voltage based on the O2 level in the exhaust gas to the computer. Typically a single wire oxygen sensor will take 3-5 minutes to reach operating temperature. The more expensive heated sensors (3 to 5 wires) can reach operating temperature in 1 minute.

The simplest sort of diagnostic an oxygen sensor can perform is related to the closed loop control system. If the system makes a change to the air-fuel ratio based on oxygen sensor readings, and the readings do not change, the sensor will light an indicator on the instrument panel warning the operator that there is a problem with the vehicle. There is a delay before this happens - usually five minutes of engine operation. Most systems do not store the state, so turning off the engine and turning it back on will reset the system, and if the error is transient the light will not come back on. However, if the problem is recurring, the light will come on as soon as the sensor reaches operating temperature and a manufacturer-defined driving pattern known as a drive-trace is completed. Until this procedure has finished, the diagnostic computer will set a parameter called a readiness monitor to "unready". The readiness monitor system was implemented in order to ensure that diagnostic computers would not falsely report working emissions systems in vehicles whose computer's error memory had recently been cleared. Such diagnostics have been factory fitted to automobiles since 1985 in North America and factory fitted to off-road spark ignition engines since 2004.

The second sort of diagnostic is more complex and is a result of the California OBD-II rule (though temperature sensors are sometimes used for this). In vehicles with OBD-II, a second oxygen sensor is fitted after the catalytic converter to monitor the O2 levels. The on-board computer makes comparisons between the readings of the two sensors. If both sensors give the same output, the catalytic converter is non-functioning, and must be replaced. It will also spot less serious damage to a catalytic converter, such as the use of leaded racing fuel in an on-road vehicle.

Car Catalytic converter NOx sensors

NOx sensors are extremely expensive and are generally only used when a compression ignition engine is fitted with a selective catalytic reduction converter, or a NOx adsorber catalyst in a feedback system. When fitted to an SCR system, there may be one or two sensors. When one sensor is fitted it will be pre-catalyst, when two are fitted the second one is post catalyst. They are utilized for the same reasons and in the same manner as an oxygen sensor - the only difference is the substance being monitored.

Car door

A car door is generally an opening to enter to the car (or their compartments or partition), often equipped with a hinged or sliding panel which can be moved to leave the opening accessible, or to close it more or less securely.

Car door Brakes

Car doors generally include a three-stage door brake.

Car door Parts

Car glass

Door handles

Door switch (simple on/off mechanism ; when the car door is open, the switch is off).

Running board

Passenger side dash mounted storage box.

Car door Situations

Front door

Rear door

Trunk or boot

Car door Types

Manual Electric (power opening and closing).

Car door Number of doors

Cars are usually sold as "three-door" or "five-door" models. In these cases, the number includes the trunk or boot door, so a three-door car has two front doors plus the trunk, and a five-door car has two front doors, two rear doors and the trunk.

Car door Being doored

Cyclists refer to colliding with an open car door as "being doored". This usually happens when the cyclist is biking alongside a row of parallel-parked cars, and a driver suddenly opens his or her door immediately in front of the cyclist.

Clutch

Clutch Flywheel

Clutch for a drive shaft: The clutch disc (center) spins with the flywheel (left). To disengage, the lever is pulled (black arrow), causing a white pressure plate (right) to disengage the green clutch disc from turning the drive shaft, which turns within the thrust-bearing ring of the lever. At rest, all 3 rings connect, with no gaps. Rear side of a Ford V6 engine, looking at the clutch housing on the flywheel Single, dry, clutch friction disc. The splined hub is attached to the disc with springs to damp chatter.A clutch is a mechanism for transmitting rotation, which can be engaged and disengaged. Clutches are useful in devices that have two rotating shafts. In these devices, one shaft is typically driven by a motor or pulley, and the other shaft drives another device. In a drill, for instance, one shaft is driven by a motor, and the other drives a drill chuck. The clutch connects the two shafts so that they can either be locked together and spin at the same speed, or be decoupled and spin at different speeds.

Clutch Vehicle clutches

There are many different vehicle clutch designs but most are based on one or more friction discs, pressed tightly together or against a flywheel using springs. The friction material varies in composition depending on whether the clutch is dry or wet, and on other considerations. Friction discs once contained asbestos, but this has been largely eliminated. Clutches found in heavy duty applications such as trucks and competition cars use ceramic clutches that have a greatly increased friction coefficient, however these have a "grabby" action and are unsuitable for road cars. The spring pressure is released when the clutch pedal is depressed thus either pushing or pulling the diaphragm of the pressure plate, depending on type, and the friction plate is released and allowed to rotate freely.

When engaging the clutch, the engine speed may need to be increased from idle, using the manual throttle, so that the engine does not stall (although in most cars, especially diesels, there is enough power at idling speed that the car can move. This requires fine control of the clutch). However, raising the engine speed too high while engaging the clutch will cause excessive clutch plate wear. Engaging the clutch abruptly when the engine is turning at high speed causes a harsh, jerky start. This kind of start is desired in drag racing and other competitions, however.

Clutch Wet and dry clutches

A 'wet clutch' is immersed in a cooling lubricating fluid, which also keeps the surfaces clean and gives smoother performance and longer life. Wet clutches, however, tend to lose some energy to the liquid. A 'dry clutch', as the name implies, is not bathed in fluid. Since the surfaces of a wet clutch can be slippery (as with a motorcycle clutch bathed in engine oil), stacking multiple clutch disks can compensate for slippage.

Clutch Clutch operation in automobiles

In a car the clutch is operated by the left-most pedal using hydraulics or a cable connection from the pedal to the clutch mechanism. Even though the clutch may physically be located very close to the pedal, such remote means of actuation are necessary to eliminate the effect of slight engine movement, engine mountings being flexible by design. With a rigid mechanical linkage, smooth engagement would be near-impossible, because engine movement inevitably occurs as the drive is "taken up". No pressure on the pedal means that the clutch plates are engaged (driving), while depressing the pedal disengages the clutch plates, allowing the driver to shift gears or coast.

A manual transmission contains cogs for selecting gears. These cogs have matching teeth, called dog teeth, which means that the rotation speeds of the two parts have to match for engagement. This speed matching is achieved by a secondary clutch called a synchronizer, a device that uses frictional contact to bring the two parts to the same speed, and a locking mechanism called a blocker ring to prevent engagement of the teeth (full movement of the shift lever into gear) until the speeds are synchronized.

Clutch Non-powertrain clutches in automobiles

There are other clutches found in a car. For example, a belt-driven engine cooling fan may have a clutch that is heat-activated. The driving and driven elements are separated by a silicone-based fluid. When the temperature is low, the fluid is thin and so the clutch slips. When the temperature is high, the fluid thickens, causing the fan to spin. There are also electronically engaged clutches (such as for anAir conditioning compressor) that use magnetic force to lock the pulley and compressor together.

Clutch Clutch operation in motorcycles

On most motorcycles, the clutch is operated by the clutch lever, located on the left handlebar. No pressure on the lever means that the clutch plates are engaged (driving), while pulling the lever back towards the rider will disengage the clutch plates, allowing the rider to shift gears. Motorcycle clutches are usually made up of a stack of alternating plain steel and friction plates. One type of plate has lugs on its inner diameter that key it to the engine crankshaft, while the other type of plate has lugs on its outer diameter that key it to a basket that turns the transmission input shaft. The plates are forced together by a set of coil springs when the clutch is engaged. Racing motorcycles often use slipper clutches to eliminate the effects of engine braking.

Clutch Centrifugal clutches

Cylinder head

A 302/5.0L Ford cylinder head.In an internal combustion engine, the cylinder head sits atop the cylinders and consists of a platform containing part of the combustion chamber and the location of the valves and spark plugs. In a flathead engine, the mechanical parts of the valve train are all contained within the block, and the head is essentially a flat plate of metal bolted to the top of the cylinder bank with a head gasket in between; this simplicity leads to ease of manufacture and repair, and accounts for the flathead engine's early success in production automobiles and continued success in small engines, such as lawnmowers. This design, however, requires the incoming air to flow through a convoluted path, which limits the ability of the engine to perform at higher rpm, leading to the adoption of the overhead valve head design.

In the overhead valve head, the top half of the cylinder head contains the camshaft in an overhead cam engine, or another mechanism (such as rocker arms and pushrods) to transfer rotational mechanics from the crankshaft to linear mechanics to operate the valves (pushrod engines perform this conversion at the camshaft lower in the engine and use a rod to push a rocker arm that acts on the valve). Internally the cylinder head has passages called ports for the fuel/air mixture to travel to the inlet valves from the intake manifold, for exhaust gases to travel from the exhaust valves to the exhaust manifold, and for antifreeze to cool the head and engine.

The number of cylinder heads in an engine is a function of the engine configuration. A straight engine has only one cylinder head. A V engine usually has two cylinder heads, one at each end of the V, although Volkswagen, for instance, produces a V6 called the VR6, where the angle between the cylinder banks is so narrow that it utilizes a single head. A boxer engine has two heads.

The cylinder head is key to the performance of the internal combustion engine, as the shape of the combustion chamber, inlet passages and ports (and to a lesser extent the exhaust) determines a major portion of the volumetric efficiency and compression ratio of the engine.

Dashboard

The dashboard of a modern car, a Bentley Continental GTCA dashboard, dash, and sometimes fascia (chiefly in British English) is a control panel located under the windshield of an automobile. It contains instrumentation and controls pertaining to operation of the vehicle.

Originally, a dashboard was the upturned screen of wood or leather placed on the front of a horse-drawn carriage, sleigh or other vehicle that protected the driver from mud, debris, water and snow thrown up by the horse's hooves.

Dashboard Types of dashboards

Lawn mowers, farm tractors, and earlier automobiles sometimes have little more than a steering wheel and some form of ignition or power switch.

Custom-built racing cars often simply have a piece of sheet metal that forms the dashboard. Whenever a new gauge needs to be added, a hole is drilled in the appropriate location. Open wheeled racing cars often have no space for a dashboard, so the instrument cluster is integrated into the center of the steering wheel.

Motorcycles and mopeds have a compressed version of car dashboards, but nevertheless larger machines sometimes have enough room for items such as audio equipment and GPS navigation.

Dashboard Dashboard and centre console layout

Increasingly, manufacturers are experimenting with moving all display portions to the center console. Various arguments are put forward for this, including cost savings when constructing both left- and right-hand-drive versions.

Dashboard Padded dashboards and safety

Padded dashboards were advocated in the 1940s by car safety pioneer Claire L. Straith.

Under the aegis of a safety program initiated by Robert McNamara (see The Fog of War documentary), padded "safety" dashboards were introduced in 1956 by Ford under the name "Safeguard". Consumers showed little interest.

One of the safety enhancements of the 1970s was the widespread adoption of padded dashboards. The padding is commonly polyurethane foam, while the surface is commonly either polyvinyl chloride (PVC) or leather in the case of luxury models.

In the 1990s, airbags became a common fitment on dashboards, and are mandatory in some countries.

Dashboard Dashboard items

Dashboard instruments displaying various car and engine conditionsItems located on the dashboard first included the steering wheel and the instrument cluster. The instrument cluster pictured to the right conatins gauges such as a speedometer, tachometer, odometer, fuel gauge, and indicators such as a gear shift position, seat belt warning light, and engine malfunction light. Later came heating and ventilation controls and vents, lighting controls, and audio equipment. In more modern cars, automotive navigation systems are mounted in the dashboard.

Dashboard Audio equipment

The first audio component other than a radio was a monophonic phonograph option on some Chrysler cars well before the cassette or eight-track tape players, which could only be operated when the car was stopped. Graphic equalizers and controls for increased bass came next, and finally CD players.

The audio system controls (such as radio and CD player) may also be on the dashboard, although volume and tuning, for example, may be controlled from a stalk beside the steering wheel.

The top of a dashboard may contain speakers for an audio system, and vents for the heating and air conditioning system. A glovebox is often found on the passenger side, and sometimes on both sides.

Dashboard Fashion in instrumentation

In the 1940s through the 1960s, American car manufacturers and their imitators designed unusually-shaped instruments on a dashboard laden with chrome and transparent plastic, which could be less readable but was often thought to be more stylish. Sunlight could cause a bright glare on the chrome, particularly for a convertible.

With the coming of the LED in consumer electronics, some manufacturers used instruments with digital readouts to make their cars appear more up to date, but this has faded from practise. Some cars use a head-up display to project the speed of the car onto the windscreen in imitation of fighter aircraft, but in a far less complex display.

Differential (mechanical device)

Input torque is applied to the ring gear, which turns the entire carrier (all blue), providing torque to both side gears (red and yellow), which in turn may drive the left and right wheels. If the resistance at both wheels is equal, the planet gear (green) does not rotate, and both wheels turn at the same rate.

If the left side gear (red) encounters resistance, the planet gear (green) rotates about the left side gear, in turn applying extra rotation to the right side gear (yellow). In an automobile and other wheeled vehicles, a differential is a device, usually consisting of gears, that allows each of the driving wheels to rotate at different speeds, while supplying equal torque to each of them. In automotive applications it is sometimes referred to as a "pumpkin".

Differential Purpose

A vehicle's wheels rotate at different speeds, especially when turning corners. The differential is designed to drive a pair of wheels with equal force, while allowing them to rotate at different speeds. In vehicles without a differential, such as karts, both driving wheels are forced to rotate at the same speed, usually on a common axle driven by a simple chain-drive mechanism. When cornering, the inner wheel travels a shorter distance than the outer wheel, resulting in the inner wheel spinning and/or the outer wheel dragging. This results in difficult and unpredictable handling, damage to tires and roads and strain on, and possible failure of the entire drive train.

Differential History

There are many claims to the invention of the differential gear, but it is likely that it was known, at least in some places, in ancient times. Here are some of the milestones in the history of this device.

1050 BC-771 BC: The Book of Song claimed the South Pointing Chariot, which uses a differential gear, was invented during the Western Zhou Dynasty.

150 BC - 100 BC - The Antikythera mechanism, discovered on an ancient shipwreck near the Greek island of Antikythera, employed a differential gear.

227 - 239 AD - Despite doubts from fellow ministers at court, Ma Jun from the Kingdom of Wei in China invents the first historically verifiable South Pointing Chariot, which provided cardinal direction as a non-magnetic, mechanized compass.

658, 666 AD - two Chinese Buddhist monks and engineers create South Pointing Chariots for Emperor Tenji of Japan.

1027, 1107 AD - Documented Chinese reproductions of the South Pointing Chariot by Yan Su and then Wu Deren, which described in detail the mechanical functions and gear ratios of the device much more so than earlier Chinese records.

1720 - Joseph Williamson uses a differential gear in a clock.

1810 - Rudolph Ackermann of Germany invents a four-wheel steering system for carriages, which some later writers mistakenly report as a differential.

1827 - modern automotive differential patented by watchmaker Onésiphore Pecqueur (1792-1852) of the Conservatoire des Arts et

Métiers in France for use on a steam car. Sources: Britannica Online.

1832 - Richard Roberts of England patents 'gear of compensation', a differential for road locomotives.

1876 - James Starley of Coventry invents chain-drive differential for use on bicycles; invention later used on automobiles by Karl Benz.

1897 - first use of differential on an Australian steam car by David Shearer.

1913 - Packard introduces the spiral-gear differential, which cuts gear noise.

1926 - Packard introduces the hypoid differential, which enables the propeller shaft and its hump in the interior of the car to be lowered.

Differential Functional description

The differential on the rear axle of a carThe following description of a differential applies to a "traditional" rear-wheel-drive car or truck: Power is supplied from the engine, via the gearbox, to a driveshaft (British term: propeller shaft), which runs to the rear axle. A pinion gear at the end of the propeller shaft is encased within the differential itself, and it engages with the large ring gear (British term: crownwheel), shown in the diagrams. The ring gear is attached to a carrier, which holds a set of small planetary gears. The three planetary gears are set up in such a way that the two outer gears (the side gears) can rotate in opposite directions relative to each other. The pair of side gears drive the axle shafts to each of the wheels. The entire carrier rotates in the same direction as the ring gear, but within that motion, the side gears can counter-rotate relative to each other.

Thus, for example, if the car is making a turn to the right, the main ring gear may make 10 full revolutions, and during that time, the left wheel will speed up because it has further to travel, and the right wheel will slow down correspondingly, as it has less distance to travel. The side gears will turn in opposite directions relative to each other by, say, 2 full turns each (4 full turns with regard to each other), resulting in the left wheel making 12 revolutions, and the right wheel making 8 revolutions.

When the vehicle is travelling in a straight line, there will be no movement of the planetary system of gears other than the minute movements necessary to compensate for slight differences in wheel diameter, undulations in the road (which make for a longer or shorter wheel path), etc.

Differential Loss of traction

One undesirable side effect of a differential is that it can reduce overall torque - the rotational force which propels the vehicle. The amount of torque required to propel the vehicle at any given moment depends on the load at that instant - how heavy the vehicle is, how much drag and friction there is, the gradient of the road, the vehicle's momentum and so on. For the purpose of this article, we will refer to this amount of torque as the "threshold torque".

The torque on each wheel is a result of the engine and transmission applying torsion, a twisting force, against the resistance of the traction at that wheel. Unless the load is exceptionally high, the engine and transmission can usually supply as much torque as necessary, so the limiting factor is usually the traction under each wheel. It is therefore convenient to define traction as the amount of torque that can be generated between the tire and the ground before the wheel starts to slip. If the total traction under all the driven wheels exceeds the threshold torque, the vehicle will be driven forward; if not, then one or more wheels will simply spin.

To illustrate how a differential can limit overall torque, imagine a simple rear-wheel-drive vehicle, with one rear wheel on asphalt with good grip, and the other on a patch of slippery ice. With the load, gradient, etc., the vehicle requires, say, 2000 Nm of torque to move forward (i.e. the threshold torque). Let us further assume that the non-spinning traction on the ice equates to 400 Nm, and the asphalt to 3000 Nm.

If the two wheels were driven without a differential, each wheel would push against the ground as hard as possible. The wheel on ice would quickly reach the limit of traction (400 Nm), but would be unable to spin because the other wheel has good traction. The traction of the asphalt plus the small extra traction from the ice exceeds the threshold requirement, so the vehicle will be propelled forward.

With a differential, however, as soon as the "ice wheel" reaches 400 Nm, it will start to spin, and then develop less traction~300Nm. The planetary gears inside the differential carrier will start to rotate because the "asphalt wheel" encounters greater resistance. Instead of driving the asphalt wheel with more force, the differential will allow the ice wheel to spin faster, and the asphalt wheel to remain stationary, compensating for extra speed of the spinning ice wheel. The torque on both wheels will be the same - limited to the lesser traction of 300 Nm each. Since 600 Nm is less than the required threshold of 2000 Nm, the vehicle will not be able to move.

Note that an observer will simply see one stationary wheel and one spinning wheel. It will not be obvious that both wheels are generating the same torque (i.e. both wheels are in fact pushing equally, despite the difference in rotational speed). This has led to a widely held misconception that a vehicle with a differential is really only "one-wheel-drive". In fact, a normal differential always provides equal torque to both driven wheels (unless it is a locking, torque-biasing, or limited slip type).

Differential Traction-adding devices

There are various devices for getting more traction from vehicles with differentials.

ARB, Air Locking DifferentialOne solution is the limited slip differential (LSD), the most well-known of which is the clutch-type LSD. With this differential, the side gears are coupled to the carrier via a stack of clutch plates which limits the speed difference between the two wheels.

A locking differential employs a mechanism for allowing the planetary gears to be locked relative to each other, causing both wheels to turn at the same speed regardless of which has more traction; this is equivalent to removing the differential entirely.

The torsen differential keeps sending some torque to the wheel with more resistance

Electronic traction control systems usually use the ABS system to detect a spinning wheel and apply the brake to it. This progressively raises the reaction torque at that wheel, and the differential compensates by transmitting more torque through the other wheel - the one with better traction.

A viscous coupling unit replaces the differential entirely. It works on the principle of allowing the two output shafts to counter-rotate relative to each other within a viscous fluid. The fluid allows slow relative movements of the shafts, such as those caused by cornering, but will strongly resist high-speed movements, such as those caused by a single wheel spinning.

A four-wheel-drive vehicle will have at least two differentials (one for each pair of wheels) and possibly a center differential to apportion power between the front and rear axles. Vehicles without a center differential should not be driven on dry, paved roads in four wheel drive mode, as small differences in rotational speed between the front and rear wheels cause a torque to be applied across the transmission. This phenomenon is known as "wind-up" and can cause damage to the transmission. On loose surfaces these differences are absorbed by the slippage on the road surface.

The NP242 is an example of a transfer case that acts as a center differential allowing the drive shafts to spin at different speeds. This permits the four-wheel-drive vehicle to drive on paved surfaces without experiencing "wind-up".

Differential Non-automotive applications

Reconstructed 19th century carding mill differentialA differential gear train can also be used to give the difference between two input axles. Mills often used such gears to apply torque in the required axis.

The oldest known example of a differential was once thought to be in the Antikythera mechanism. It was supposed to have used such a train to produce the difference between two inputs, one input related to the position of the sun on the zodiac, and the other input related to the position of the moon on the zodiac; the output of the differential gave a quantity related to the moon's phase. It has now been proven that the assumption of the existence of a differential gearing arrangement was incorrect.

In the first half of the twentieth century, mechanical analog computers, called differential analyzers, were constructed that used differential gear trains to perform addition and subtraction.

Differential Active differentials

A relatively new technology is the electronically-controlled active differential. A computer uses inputs from multiple sensors, including yaw rate, steering angle, and lateral acceleration and adjusts the distribution of torque to compensate for undesirable handling behaviors like understeer. Active differentials used to play a large role in the World Rally Championship, but in the 2006 season the FIA has limited the use of active differentials only to those drivers who have not competed in the World Rally Championship in the last five years.

Fully integrated active differentials are used on the Ferrari F430 and on the rear wheels in the Acura RL.

The second constraint of the differential is passive it is actuated by the friction kinematics chain through the ground. The difference in torque on the tires (caused by turns or bumpy ground) drives the second degree of freedom, (overcoming the torque of inner friction) to equalise the driving torque on the tires. The sensitivity of the differential depends on the inner friction through the second degree of freedom. All of the differentials (so called active and passive) use clutches and brakes for restricting the second degree of freedom, so all suffer from the same disadvantage decreased sensitivity to a dynamically changing environment. The sensitivity of the computer controlled differential is also limited by the time delay caused by sensors and the response time of the actuators.

Driveshaft

Driveshafts are carriers of torque: they are subject to torsion and shear stress, which represents the difference between the input force and the load. They thus need to be strong enough to bear the stress, without imposing too great an additional inertia by virtue of the weight of the shaft.

Driveshaft Automotive driveshafts

Driveshaft Vehicles

Most automobiles today use rigid driveshafts to deliver power from a transmission to the wheels. A pair of short driveshafts is commonly used to send power from a central differential, transmission, or transaxle to the wheels.

In front-engined, rear-drive vehicles, a longer driveshaft is also required to send power the length of the vehicle. Two forms dominate: The torque tube with a single universal joint and the Hotchkiss drive with two or more joints. This system became known as Système Panhard after the automobile company, Panhard et Levassor patented it.

Early automobiles often used chain drive or belt drive mechanisms rather than a driveshaft. Some used electrical generators and motors to transmit power to the wheels.

In British English, the term "driveshaft" is restricted to a transverse shaft which transmits power to the wheels, especially the front wheels. A driveshaft connecting the gearbox to a rear differential is called a propeller shaft (or more commonly a "prop-shaft") and a driveshaft connecting a rear differential to a rear wheel is usually called a halfshaft. The name derives from the fact that two such shafts are required to form one rear axle.

There are different types of driveshafts in Automotive Industry:

1 piece driveshaft

2 piece driveshaft

Driveshaft Slip in Tube driveshaft

The Slip in Tube Driveshaft is the new type which also helps in Crash Energy Management. It can be compressed in case of crash.

It is also known as a collapsible driveshaft.

Driveshaft Driveshaft for Research and Development (R&D)

The automotive industry also uses driveshafts at testing plants. At an engine test stand a drive shaft is used to transfer a certain speed / torque from the combustion engine to a dynamometer. A "shaft guard" is used at a shaft connection to protect against contact with the drive shaft and for detection of a shaft failure. At a transmission test stand a drive shaft connects the prime mover with the transmission.

Driveshaft Motorcycle driveshafts

Driveshafts have been used on motorcycles almost as long as there have been motorcycles. As an alternative to chain and belt drives, driveshafts offer relatively maintenance-free operation and long life. A disadvantage of shaft drive on a motorcycle is that gearing is needed to turn the power 90° from the shaft to the rear wheel, losing some power in the process. On the other hand, it is easier to protect the shaft linkages and drive gears from dust, sand and mud.

The best known motorcycle manufacturer to use shaft drive for a long time since 1923 is BMW. Among contemporary manufacturers, Moto Guzzi is also well-known for its shaft drive motorcycles. The British company, Triumph and all four Japanese brands, Honda, Suzuki, Kawasaki and Yamaha, have produced shaft drive motorcycles.

The first use of a driveshaft on an off-road motorcycle was in the Tote Gote Nova series. It used a straight shaft powering a worm gear which then turned a gear. The outer casing was aluminum, and was supported by two rubber bushings. The engine faced forward in the frame.

Motorcycle engines positioned such that the crankshaft is longitudinal and parallel to the frame are often used for shaft driven motorcycles. The requires only one 90° turn in power transmission, rather than two. Moto Guzzi, BMW, Triumph, and Honda use this engine layout.

Motorcycles with shaft drive are subject to shaft effect where the chassis climbs when power is applied. This is counteracted with systems such as BMW's Paralever, Moto Guzzi's CARC and Kawasaki's Tetralever.

Driveshaft Marine driveshafts

On a power-driven ship, the driveshaft, or propeller shaft, usually connects the transmission inside the vessel directly to the propeller, passing through a stuffing box or other seal at the point it exits the hull.

As the rotating propeller pushes the vessel forward, the marine driveshaft is also subject to compression, and when going reverse, to tension.

Cardan shafts are also often used in marine applications between the transmission and either a propeller gearbox or waterjet.

Driveshaft Driveshafts in Bicycles

A shaft-driven bicycle.The driveshaft has served as an alternative to a chain-drive in bicycles for the past century, although never becoming very popular. A shaft-driven bicycle is described as "acatane". When used on a bicycle, a driveshaft has several advantages and disadvantages:

Driveshaft Advantages

Drive system is less likely to become jammed or broken, a common problem with chain-driven bicycles The use of a gear system creates a smoother and more consistent pedalling motion

The rider cannot become dirtied from chain grease or injured by the chain from "Chain bite", which occurs when clothing or even a body part catches between the chain and a sprocket

Lower maintenance than a chain system when the driveshaft is enclosed in a tube, the common convention

More consistent performance. Dynamic Bicycles claims that a driveshaft bicycle consistently delivers 94% efficiency, whereas a chain-driven bike can deliver anywhere from 75-97% efficiency based on condition.

Greater clearance: with the absence of a derailleur or other low-hanging machinery, the bicycle has nearly twice the ground clearance

Driveshaft Disadvantages

A driveshaft system weighs more than a chain system, usually 1-2 pounds heavier

At optimum upkeep, a chain delivers greater efficiency

Many of the advantages claimed by driveshaft's proponents can be achieved on a chain-driven bicycle, such as covering the chain and gears with a metal or plastic cover

Use of lightweight derailleur gears with a high number of ratios is impossible, although hub gears can be used

Wheel removal can be complicated in some designs (as it is for some chain-driven bicycles with hub gears).

Engine control unit

An engine control unit (ECU) is an electronic control unit which controls various aspects of an internal combustion engine's operation. The simplest ECUs control only the quantity of fuel injected into each cylinder each engine cycle. More advanced ECUs found on most modern cars also control the ignition timing, variable valve timing (VVT), the level of boost maintained by the turbocharger (in turbocharged cars), and control other peripherals.

E11: An aftermarket ECUECUs determine the quantity of fuel, ignition timing and other parameters by monitoring the engine through sensors. These can include, MAP sensor, throttle position sensor, air temperature sensor, oxygen sensor and many others. Often this is done using a control loop (such as a PID controller).

Before ECUs most engine parameters were fixed. The quantity of fuel per cylinder per engine cycle was determined by a carburetor or injector pump.

Engine control unit ECU operation

Engine control unit Control of fuel injection

For an engine with fuel injection, an ECU will determine the quantity of fuel to inject based on a number of parameters. If the throttle pedal is pressed further down, this will open the throttle body and allow more air to be pulled into the engine. The ECU will inject more fuel according to how much air is passing into the engine. If the engine has not warmed up yet, more fuel will be injected (causing the engine to run slightly 'rich' until the engine warms up).

Engine control unit Control of ignition timing

A spark ignition engine requires a spark to initiate combustion in the combustion chamber. An ECU can adjust the exact timing of the spark (called ignition timing) to provide better power and economy. If the ECU detects knock, a condition which is potentially destructive to engines, and "judges" it to be the result of the ignition timing being too early in the compression stroke, it will delay (retard) the timing of the spark to prevent this.

A second, more common source, cause, of knock/ping is operating the engine in too low of an RPM range for the "work" requirement of the moment. In this case the knock/ping results from the piston not being able to move downward as fast as the flame front is expanding.

But this latter mostly applies only to manual transmission equipped vehicles. The ECU controlling an automatic transmission would simply downshift the transmission were this the cause of knock/ping.

Engine control unit Control of variable valve timing

Some engines have Variable Valve Timing. In such an engine, the ECU controls the time in the engine cycle at which the valves open. The valves are usually opened later at higher speed than at lower speed. This can optimise the flow of air into the cylinder, increasing power and economy.

Engine control unit Control of starting

A relatively recent application of engine control is the use of precisely timed injection and ignition to start an engine without the use of a starter motor. Such a static-start engine would provide the efficiency and pollution-reductiton improvements of a mild hybrid-electric drive, but without the expense and complexity of an oversized starter motor.

Engine control unit Programmable ECUs

A special category of ECUs are those which are programmable. These units do not have a fixed behavior, but can be reprogrammed by the user.

Programmable ECUs are required where significant aftermarket modifications have been made to a vehicle's engine. Examples include adding or changing of a turbocharger, adding or changing of an intercooler, changing of the exhaust system, and conversion to run on alternative fuel. As a consequence of these changes, the old ECU may not provide appropriate control for the new configuration. In these situations, a programmable ECU can be wired in. These can be programmed/mapped with a laptop connected using a serial or USB cable, while the engine is running.

The programmable ECU may control the amount of fuel to be injected into each cylinder. This varies depending on the engine's RPM and the position of the gas pedal (or the manifold air pressure). The engine tuner can adjust this by bringing up a spreadsheet-like page on the laptop where each cell represents an intersection between a specific RPM value and a gas pedal position (or the throttle position, as it is called). In this cell a number corresponding to the amount of fuel to be injected is entered.

By modifying these values while monitoring the exhausts using a wide band lambda probe to see if the engine runs rich or lean, the tuner can find the optimal amount of fuel to inject to the engine at every different combination of RPM and throttle position. This process is often carried out at a dynamometer, giving the tuner a controlled environment to work in.

Other parameters that are often mappable are:

Ignition: Defines when the spark plug should fire for a cylinder.

Rev limit: Defines the maximum RPM that the engine is allowed to rev to. After this fuel and/or ignition is cut.

Water temperature correction: Allows for additional fuel to be added when the engine is cold (choke).

Transient fueling: Tells the ECU to add a specific amount of fuel when throttle is applied.

Low fuel pressure modifier: Tells the ECU to increase the injector fire time to compensate for a loss of fuel pressure.

Closed loop lambda: Lets the ECU monitor a permanently installed lambda probe and modify the fueling to achieve stoichiometric (ideal) combustion.

Some of the more advanced race ECUs include functionality such as launch control, limiting the power of the engine in first gear to avoid burnouts. Other examples of advanced functions are:

Waste gate control: Sets up the behavior of a turbo waste gate, controlling boost. Banked injection: Sets up the behavior of double injectors per cylinder, used to get a finer fuel injection control and atomization over a wide RPM range.

Variable cam timing: Tells the ECU how to control variable intake and exhaust cams. Gear control: Tells the ECU to cut ignition during (sequential gearbox) upshifts or blip the throttle during downshifts.

A race ECU is often equipped with a data logger recording all sensors for later analysis using special software in a PC. This can be useful to track down engine stalls, misfires or other undesired behaviors during a race by downloading the log data and looking for anomalies after the event. The data logger usually has a capacity between 0.5 and 16 Mbytes.

In order to communicate with the driver, a race ECU can often be connected to a "data stack", which is a simple dash board presenting the driver with the current RPM, speed and other basic engine data. These race stacks, which are almost always digital, talk to the ECU using one of several proprietary protocols running over RS232, CANbus.

Engine control unit ECU flashing

Example reflash tuning softwareMany recent (around 1996 or newer) cars use OBD-II ECUs that are sometimes capable of having their programming changed through the OBD port.

Automotive enthusiasts with modern cars take advantage of this technology when tuning their engines. Rather than use an entire new engine management system, one can use the appropriate software to adjust the factory equipped computer. By doing so, it is possible to retain all stock functions and wiring while using a custom tuned program. This should not be confused with "chip tuning", where the owner has ECU ROM physically replaced with a different one -- no hardware modification is (usually) involved with flashing ECUs, although special equipment is required.

Factory engine management systems often have similar controls as aftermarket units intended for racing, such as 3-dimensional timing and fuel control maps. They generally do not have the ability to control extra ancillary devices, such as variable valve timing if the factory vehicle was a fixed geometry camshaft or boost control if the factory car was not turbocharged.

Engine control unit History

Engine control unit Hybrid digital designs

A hybrid digital design was popular in the mid-'80s. This used analogue techniques to measure and process input parameters from the engine, then used a look-up table stored in a digital ROM chip to yield precomputed output values. Later systems compute these outputs dynamically. The ROM type of system is amenable to tuning if one knows the system well. The disadvantage of such systems is that the precomputed values are only optimal for an idealised, new engine. As the engine wears, the system is less able to compensate than a CPU based system.

Sophisticated engine management systems receive inputs from other sources, and control other parts of the engine; for instance, some variable valve timing systems are electronically controlled, and turbocharger wastegates can also be managed. They also may communicate with transmission control units or directly interface electronically-controlled automatic transmissions, traction control systems, and the like. The Controller Area Network or CAN bus automotive network is often used to achieve communication between these devices.

Engine control unit Modern ECUs

Modern ECUs use a microprocessor which can process the inputs from the engine sensors in real time. An electronic control unit contains the hardware and software (firmware). The hardware consists of electronic components on a printed circuit board (PCB). The main component on this circuit board is a microcontroller chip (CPU). The software is stored in the microcontroller or other chips on the PCB, typically in EPROMs or flash memory so the CPU can be re-programmed by uploading updated code. This is also referred to as an (electronic) Engine Management System (EMS).

Engine control unit Other applications

Such systems are used for many internal combustion engines in other applications. In aeronautical applications, the systems are known as "FADECs" (Full Authority Digital Engine Controls). This kind of electronic control is less common in piston-engined aeroplanes than in automobiles, because of the large costs of certifying parts for aviation use, relatively small demand, and the consequent stagnation of technological innovation in this market. Also, a carburated engine with magneto ignition and a gravity feed fuel system does not require any electrical power to run, which is a safety bonus.

Engine control unit ECU failures

As usually occurs with a technology shift, computer-controlled engine management has replaced old failure modes with new ones. With advanced age, a failing ECU can cause seemingly random starting and driveability faults. For example, a vehicle may refuse to start when cranked with the starter motor, but may respond easily to a push start. Failing electrolytic capacitors in the ECU no longer smooth the power supply to the microprocessor, and the varying load on the starter motor causes sufficient line voltage fluctuation that the computer reboots repeatedly while attempting to start the engine. An industry has evolved to refurbish ECUs with this and other types of failures related to age and use.

Exhaust system

Exhaust pipe of a carAn exhaust system is usually tubing used to guide waste exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine an