Anti-lock braking system From Wikipedia, the free encyclopedia This article needs additional citations for verification . Please help improve this article by adding reliable references . Unsourced material may be challenged and removed . (December 2010) An anti-lock braking system (ABS, from German: Antiblockiersystem) is a safety system that allows the wheels on a motor vehicle to continue interacting tractively with the road surface as directed by driver steering inputs while braking , preventing the wheels from locking up (that is, ceasing rotation) and therefore avoiding skidding . An ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces for many drivers; however, on loose surfaces like gravel or snow-covered pavement, an ABS can significantly increase braking distance, although still improving vehicle control. [1] Since initial widespread use in production cars, anti-lock braking systems have evolved considerably. Recent versions not only prevent wheel lock under braking, but also electronically control the front-to-rear brake bias. This function, depending on its specific capabilities and implementation, is known as electronic brakeforce distribution (EBD), traction control system , emergency brake assist , or electronic stability control (ESC). Operation The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake). [9] A typical ABS includes a central electronic control unit (ECU), four wheel speed sensors , and at least two hydraulic valves within the brake hydraulics . The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the
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Anti-lock braking systemFrom Wikipedia, the free encyclopedia
This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (December 2010)
An anti-lock braking system (ABS, from German: Antiblockiersystem) is a safety system that allows
the wheels on a motor vehicle to continue interacting tractively with the road surface as directed by driver
steering inputs while braking, preventing the wheels from locking up (that is, ceasing rotation) and therefore
avoiding skidding.
An ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery
surfaces for many drivers; however, on loose surfaces like gravel or snow-covered pavement, an ABS can
significantly increase braking distance, although still improving vehicle control.[1]
Since initial widespread use in production cars, anti-lock braking systems have evolved considerably.
Recent versions not only prevent wheel lock under braking, but also electronically control the front-to-rear
brake bias. This function, depending on its specific capabilities and implementation, is known as electronic
brakeforce distribution (EBD), traction control system, emergency brake assist, or electronic stability
control (ESC).
Operation
The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).[9]
A typical ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock system can apply or release braking pressure 16 times per second.[10]
The ECU is programmed to disregard differences in wheel rotative speed below a critical threshold, because when the car is turning, the two wheels towards the center of the curve turn slower than the outer two. For this same reason, a differential is used in virtually all roadgoing vehicles.
If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is rectified.
The modern ABS applies individual brake pressure to all four wheels through a control system of hub-mounted sensors and a dedicated micro-controller. ABS is offered or comes standard on most road vehicles produced today and is the foundation for ESC systems, which are rapidly increasing in popularity due to the vast reduction in price of vehicle electronics over the years.[11]
Modern electronic stability control (ESC or ESP) systems are an evolution of the ABS concept. Here, a minimum of two additional sensors are added to help the system work: these are a steering wheel angle sensor, and a gyroscopic sensor. The theory of operation is simple: when the gyroscopic sensor detects that the direction taken by the car does not coincide with what the steering wheel sensor reports, the ESC software will brake the necessary individual wheel(s) (up to three with the most sophisticated systems), so that the vehicle goes the way the driver intends. The steering wheel sensor also helps in the operation of Cornering Brake Control (CBC), since this will tell the ABS that wheels on the inside of the curve should brake more than wheels on the outside, and by how much.
The ABS equipment may also be used to implement a traction control system(TCS) on acceleration of the vehicle. If, when accelerating, the tire loses traction, the ABS controller can detect the situation and take suitable action so that traction is regained. More sophisticated versions of this can also control throttle levels and brakes simultaneously.
[edit]Components
There are four main components to an ABS: speed sensors, valves, a pump, and a controller.
The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information.
ValvesThere is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions:
In position one, the valve is open; pressure from the master cylinder is passed right through to the brake.
In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder.
In position three, the valve releases some of the pressure from the brake.
PumpSince the valve is able to release pressure from the brakes, there has to be some way to put that pressure back. That is what the pump does; when a valve reduces the pressure in a line, the pump is there to get the pressure back up.
ControllerThe controller is an ECU type unit in the car which receives information from each individual wheel speed sensor, in turn if a wheel loses traction the signal is sent to the controller, the controller will then limit the brakeforce (EBD) and activate the ABS modulator which actuates the braking valves on and off.
[edit]Use
There are many different variations and control algorithms for use in an ABS. One of the simpler systems works as follows:[10]
1. The controller monitors the speed sensors at all times. It is looking for decelerations in the wheel that are out of the ordinary. Right before a wheel locks up, it will experience a rapid deceleration. If left unchecked, the wheel would stop much more quickly than any car could. It might take a car five seconds to stop from 60 mph (96.6 km/h) under
ideal conditions, but a wheel that locks up could stop spinning in less than a second.
2. The ABS controller knows that such a rapid deceleration is impossible, so it reduces the pressure to that brake until it sees an acceleration, then it increases the pressure until it sees the deceleration again. It can do this very quickly, before the tire can actually significantly change speed. The result is that the tire slows down at the same rate as the car, with the brakes keeping the tires very near the point at which they will start to lock up. This gives the system maximum braking power.
3. When the ABS system is in operation the driver will feel a pulsing in the brake pedal; this comes from the rapid opening and closing of the valves. This pulsing also tells the driver that the ABS has been triggered. Some ABS systems can cycle up to 16 times per second.
[edit]Brake types
Anti-lock braking systems use different schemes depending on the type of brakes in use. They can be differentiated by the number of channels: that is, how many valves that are individually controlled—and the number of speed sensors.[10]
Four-channel, four-sensor ABSThis is the best scheme. There is a speed sensor on all four wheels and a separate valve for all four wheels. With this setup, the controller monitors each wheel individually to make sure it is achieving maximum braking force.
Three-channel, four-sensor ABSThere is a speed sensor on all four wheels and a separate valve for each of the front wheels, but only one valve for both of the rear wheels.
Three-channel, three-sensor ABSThis scheme, commonly found on pickup trucks with four-wheel ABS, has a speed sensor and a valve for each of the front
wheels, with one valve and one sensor for both rear wheels. The speed sensor for the rear wheels is located in the rear axle. This system provides individual control of the front wheels, so they can both achieve maximum braking force. The rear wheels, however, are monitored together; they both have to start to lock up before the ABS will activate on the rear. With this system, it is possible that one of the rear wheels will lock during a stop, reducing brake effectiveness. This system is easy to identify, as there are no individual speed sensors for the rear wheels.
One-channel, one-sensor ABSThis system is commonly found on pickup trucks with rear-wheel ABS. It has one valve, which controls both rear wheels, and one speed sensor, located in the rear axle. This system operates the same as the rear end of a three-channel system. The rear wheels are monitored together and they both have to start to lock up before the ABS kicks in. In this system it is also possible that one of the rear wheels will lock, reducing brake effectiveness. This system is also easy to identify, as there are no individual speed sensors for any of the wheels.
[edit]Effectiveness
A 2003 Australian study by Monash University Accident Research Centre found that ABS:[1]
Reduced the risk of multiple vehicle crashes by 18 percent,
Reduced the risk of run-off-road crashes by 35 percent.
On high-traction surfaces such as bitumen, or concrete, many (though not all) ABS-equipped cars are able to attain braking distances better (i.e. shorter) than those that would be easily possible without the benefit of ABS. In real world conditions even an alert, skilled driver without ABS would find it difficult, even through the use of techniques like threshold braking, to match or improve on the performance of a typical driver with a modern ABS-equipped vehicle. ABS reduces
chances of crashing, and/or the severity of impact. The recommended technique for non-expert drivers in an ABS-equipped car, in a typical full-braking emergency, is to press the brake pedal as firmly as possible and, where appropriate, to steer around obstructions. In such situations, ABS will significantly reduce the chances of a skid and subsequent loss of control.
In gravel, sand and deep snow, ABS tends to increase braking distances. On these surfaces, locked wheels dig in and stop the vehicle more quickly. ABS prevents this from occurring. Some ABS calibrations reduce this problem by slowing the cycling time, thus letting the wheels repeatedly briefly lock and unlock. Some vehicle manufacturers provide an "off-road" button to turn ABS function off. The primary benefit of ABS on such surfaces is to increase the ability of the driver to maintain control of the car rather than go into a skid, though loss of control remains more likely on soft surfaces like gravel or slippery surfaces like snow or ice. On a very slippery surface such as sheet ice or gravel, it is possible to lock multiple wheels at once, and this can defeat ABS (which relies on comparing all four wheels, and detecting individual wheels skidding). Availability of ABS relieves most drivers from learning threshold braking.
A June 1999 National Highway Traffic Safety Administration (NHTSA) study found that ABS increased stopping distances on loose gravel by an average of 22 percent.[12]
"ABS works with your regular braking system by automatically pumping them. In vehicles not equipped with ABS, the driver has to manually pump the brakes to prevent wheel lockup. In vehicles equipped with ABS, your foot should remain firmly planted on the brake pedal, while ABS pumps the brakes for you so you can concentrate on steering to safety."
When activated, some earlier ABS systems caused the brake pedal to pulse noticeably. As most drivers rarely or never brake hard enough to cause brake lock-up, and a significant number rarely bother to read the car's manual,[citation needed] this may not be discovered until an emergency. When drivers do encounter an emergency that causes them to brake hard, and thus encounter this pulsing for the first time, many are believed to reduce pedal pressure, and thus lengthen braking distances, contributing to a higher level of accidents than the superior emergency stopping capabilities of ABS would otherwise promise. Some manufacturers have therefore implemented a brake assist system that determines that the driver is attempting a "panic stop" (by detecting that the brake pedal was depressed very fast, unlike a normal stop where the pedal pressure would usually be gradually increased, Some systems additionally monitor the rate at the accelerator was released)[citation needed] and the system automatically increases braking force where not enough pressure is applied. Hard or panic braking on bumpy surfaces, because of the bumps causing the speed of the wheel(s) to become erratic may also trigger the ABS. Nevertheless, ABS significantly improves
safety and control for drivers in most on-road situations.
Anti-lock brakes are the subject of some experiments centred around risk compensation theory, which asserts that drivers adapt to the safety benefit of ABS by driving more aggressively. In a Munich study, half a fleet of taxicabs was equipped with anti-lock brakes, while the other half had conventional brake systems. The crash rate was substantially the same for both types of cab, and Wilde concludes this was due to drivers of ABS-equipped cabs taking more risks, assuming that ABS would take care of them, while the non-ABS drivers drove more carefully since ABS would not be there to help in case of a dangerous situation.[13] A similar study was carried out in Oslo, with similar results.[citation needed]
[edit]
Diesel engineA diesel engine (also known as a compression-ignition engine) is an internal combustion
engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into
the combustion chamber. This is in contrast to spark-ignition engines such as a petrol
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Injection pump for a 12-cylinder diesel engine
An Injection Pump is the device that pumps fuel into the cylinders of a diesel engine or less typically,
a gasoline engine. Traditionally, the pump is driven indirectly from the crankshaft by gears, chains or a
toothed belt (often the timing belt) that also drives the camshaft on overhead-cam engines ( OHC ). It
rotates at half crankshaft speed in a conventional four-stroke engine. Its timing is such that the fuel is
injected only very slightly before top dead centre of that cylinder's compression stroke. It is also common
for the pump belt on gasoline engines to be driven directly from the camshaft. In some systems injection
pressures can be as high as 200Mpa.
Contents
[hide]
1 Safety
2 Construction
3 New types
4 References
[edit]Safety
Because of the need for positive injection into a very high-pressure environment, the pump develops great
pressure—typically 15,000 psi (100 MPa) or more on newer systems. This is a good reason to take great
care when working on diesel systems; escaping fuel at this sort of pressure can easily penetrate skin and
clothes, and be injected into body tissues with medical consequences serious enough to
General Description – An external view of atypical pump is shown in Fig. 1 and an internalsection in Fig. 2.The main rotating components are the driveshaft (1), distributor rotor (2), transfer pumpblades (5), and governor components (11).The drive shaft engages the distributor rotorin the hydraulic head. The drive end of therotor incorporates two pumping plungers.The plungers are actuated toward eachother simultaneously by an internal cam ringthrough rollers and shoes which are carried inslots at the drive end of the rotor. The numberof cam lobes normally equals the number ofengine cylinders.Fig. 1 — PumpFig. 2 — Sectional viewThe transfer pump at the rear of the rotor isthe postive displacement vane-type and isenclosed in the end cap. The end cap alsohouses the fuel inlet strainer and transfer pumppressure regulator. Transfer pump pressure isautomatically compensated for viscosity effectsdue to both temperature changes and variousfuel grades.The distributor rotor incorporates twocharging ports and a single axial bore with onedischarge port to serve all head outlets to theinjection tubings. The hydraulic head containsthe bore in which the rotor revolves, the meteringvalve bore, the charging ports and the headoutlet fittings. The high pressure injectiontubings leading to the nozzles are fastened tothese fittings.Distributor pumps contain their ownmechanical governor capable of close speedregulation. Both all-speed and min-max typesare available. The centrifugal force of the weightsin their retainer is transmitted through a sleeveto the governor arm and through a linkage tothe metering valve. The metering valve can beclosed to shut off fuel through the linkage by anindependently operated shut-off lever.Components:1. Drive Shaft2. Distributor Rotor3. Hydraulic Head4. Delivery Valve5. Transfer Pump6. Pressure Regulator7. Discharge Fitting8. Metering Valve9. Pumping Plungers10. Internal Cam Ring11. Governor12. Governor Weights13. Advance14. Drive Shaft Bushing15. Housing16. Rollers
4Regulating pistonInlet side Regulating slotRegulating springRegulatorThin plateOrifice
Spring Adjusting PlugDischarge sideFig. 3 — Transfer pump regulatorShoeThe automatic speed advance is a hydraulicmechanism which advances or retards thebeginning of fuel delivery from the pump. Thiscan respond to speed alone, or to a combinationof speed and load changes. A more detaileddescription of each pump area will be coveredin the following pages.Transfer pump pressure regulation – Refer toFig. 3 for the following description. Filtered, lowpressure fuel from an overhead tank or a liftpump passes through the transfer pump inletscreen. This vane-type pump consists of astationary liner and four spring loaded blades,which are carried in the rotor slots. Excess fuelis recirculated to the transfer pump inlet bymeans of the pressure regulator piston, spring,and ported sleeve. Fuel pressure from thetransfer pump forces the piston in the regulatorsleeve against the spring. The pressure curve iscontrolled by the pump displacement, springrate and preload, and regulating slotconfiguration. Therefore, pressure increaseswith speed.The transfer pump operates consistentlyover a wide viscosity range determined bydifferent grades of diesel fuels and also whenaffected by varying temperatures. A thin plateincorporating a sharp-edged orifice is located inthe spring adjusting plug. Flow through anorifice of this type is virtually unaffected byviscosity changes. An additional biasing pressureis exerted against the spring side of the pistonand is determined by the linear flow aroundthe regulating piston and the flow through theorifice. With cold or viscous fuels a reducedflow occurs through the piston and sleevePlungerRotorLeaf springclearance, and the additional biasing pressure isslight. With hot or low viscosity fuels theclearance flow increases and the pressure withinthe spring chamber increases. The regulatingspring and higher biasing pressure forcescombine to control the slot area. This controlmaintains a nearly constant transfer pumppressure over a broad range of fuel viscositiesand thus maintains stable automatic advanceoperation over various fuel types andtemperatures.Hydraulic head and rotor – Fig. 4 shows anexploded view of the rotor and the pumpingplungers. The cam rollers contact the innersurface of the cam ring form and push theplungers toward each other for injection. Theshoes act as tappets betweenthe rollers and plungers.
Cam rollerLeaf spring screwFig. 4 — Rotor and plungerRefer to Fig. 5. As the rotor revolves, its twoinlet passages register with the charging annulusports in the hydraulic head. Transfer pump fuelcontrolled by the metering valve opening, flowsinto the pumping chamber forcing the plungersapart. The plungers move outward for a distanceproportional to the amount of fuel required forthe next injection stroke. If only a small amountis admitted, as at idling, the plungers move outa short distance. If half-load is required,approximately half the pumping chamber isfilled. This process is known as inlet metering.5Full-load delivery is controlled by themaximum plunger travel. This plunger travel islimited by the leaf spring as it is contacted bythe edge of the shoes.Roller betweencam lobesPlunger Meteringvalve Circularfuel passageRotorLeafspringCamShoe Inletpassages ChargingpassageIransterpumpcam lobeCam RotorOutlet fittingDeliveryRoller contactsvalve Discharge portPumpingchamberFig. 5 — Plunger chargingRefer to Fig. 6. The leaf spring contacts twopoints near the outer ends of the rotor. As theadjusting screw is turned inward, the center ofthe leaf spring moves in and its ends extendoutward. This increases the maximum plungertravel. Turning the adjusting screw out has thereverse effect. The adjustment set point isretained by the screw head-to-leaf springCam ringLeaf springPlungersFig. 6 — Cam, plungers and leaf springfriction and the coating material on the screwthreads.As the rotor continues to revolve (Fig. 7),the inlet ports move out of registry and therotor discharge port indexes with one of thehead outlets. The rollers then contact opposingcam lobes which force the shoes inward againstthe plungers. At this point high pressure pumpingbegins. Further rotation of the rotor moves theFig. 7 — Plunger dischargingrollers along the cam ramps forcing the plungers
together. During the discharge stroke the fuelbetween the plungers is displaced into the axialpassage of the rotor through the delivery valveto the discharge port. The pressurized fuel thenpasses through the outlet fitting, enters theinjection tubing and opens the nozzle. Deliverycontinues until the rollers travel over the camnoses and begin to move outwardly. The pressurein the axial passage is then reduced, allowingthe nozzle to close.6
Common railCommon rail direct fuel injection is a modern variant of direct fuel injection system
for petrol and diesel engines.
Common rail fuel injector
On diesel engines, it features a high-pressure (over 1,000 bar/15,000 psi) fuel rail feeding
individual solenoid valves, as opposed to low-pressure fuel pump feeding unit injectors (Pumpe/Düse
or pump nozzles). Third-generation common rail diesels now feature piezoelectric injectors for
increased precision, with fuel pressures up to 1,800 bar/26,000 psi.
In gasoline engines, it is utilised in gasoline direct injection engine technology.
nozzle and plunger) is mechanically or hydraulically opened and fuel is sprayed into the cylinders at
the desired pressure. Since the fuel pressure energy is stored remotely and the injectors are
electrically actuated, the injection pressure at the start and end of injection is very near the pressure in
the accumulator (rail), thus producing a square injection rate. If the accumulator, pump and plumbing
are sized properly, the injection pressure and rate will be the same for each of the multiple injection
events.
Basic Engine Parts
The core of the engine is the cylinder, with the piston moving up and down inside the cylinder. The engine described above has one cylinder. That is typical of most lawn mowers, but most cars have more than one cylinder (four, six and eight cylinders are common). In a multi-cylinder engine, the cylinders usually are arranged in one of three ways: inline, V or flat (also known as horizontally opposed or boxer), as shown in the following figures.
Figure 2. Inline - The cylinders are arranged in a line in a single bank.
Figure 3. V - The cylinders are arranged in two banks set at an angle to one another.
Figure 4. Flat - The cylinders are arranged in two banks on opposite sides of the engine.Different configurations have different advantages and disadvantages in terms of smoothness, manufacturing cost and shape characteristics. These advantages and disadvantages make them more suitable for certain vehicles.
Let's look at some key engine parts in more detail.
Spark plug The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can occur. The spark must happen at just the right moment for things to work properly.
Valves The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Note that both valves are closed during compression and combustion so that the combustion chamber is sealed.
PistonA piston is a cylindrical piece of metal that moves up and down inside the cylinder.
Piston ringsPiston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. The rings serve two purposes:
They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion.
They keep oil in the sump from leaking into the combustion area, where it would be burned and lost.Most cars that "burn oil" and have to have a quart added every 1,000 miles are burning it because the engine is old and the rings no longer seal things properly.
Connecting rodThe connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates.
Crankshaft The crankshaft turns the piston's up and down motion into circular motion just like a crank on a jack-in-the-box does.
Sump The sump surrounds the crankshaft. It contains some amount of oil, which collects in the bottom of the sump (the oil pan).
Next, we'll learn what can go wrong with engines.
Automotive batteryFrom Wikipedia, the free encyclopedia
12 V, 40 Ah Lead-acid car battery
An automotive battery is a type of rechargeable battery that supplies electric energy to an automobile.
[1] Usually this refers to an SLI battery (starting, lighting, ignition) to power the starter motor, the lights, and
the ignition system of a vehicle’s engine. An automotive battery may also be a traction battery used for the
main power source of an electric vehicle.
Automotive SLI batteries are usually lead-acid type, and are made of six galvanic cells in series to provide
a 12 volt system. Each cell provides 2.1 volts for a total of 12.6 volt at full charge. Heavy vehicles such as
highway trucks or tractors, often equipped with Diesel engines, may have two batteries in series for a 24
volt system, or may have parallel strings of batteries.
Lead-acid batteries are made up of plates of lead and separate plates of lead dioxide, which are
submerged into an electrolyte solution of about 35% sulfuric acid and 65% water.[2] This causes a chemical
reactionthat 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 sulfate. When the battery is recharged, the chemical reaction is reversed: the lead sulfate reforms
into lead oxide and lead. With the plates restored to their original condition, the process may now be
repeated.
Battery recycling of automotive batteries reduces resources required for manufacture of new batteries and
diverts toxic lead from landfills or improper disposal.
This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (April 2010)
This article is about the vehicle component. For other uses, see Brake (disambiguation).
Disc brake on a motorcycle
A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this
article is dedicated to various types of vehicular brakes.
Most commonly brakes use friction to convert kinetic energy into heat, though other methods of energy
conversion may be employed. For example regenerative braking converts much of the energy to electrical
energy, which may be stored for later use. Other methods convert kinetic energy into potential energy in
such stored forms as pressurized air or pressurized oil. Still other braking methods even transformkinetic
energy into different forms, for example by transferring the energy to a rotating flywheel.
Brakes are generally applied to rotating axles or wheels, but may also take other forms such as the surface
of a moving fluid (flaps deployed into water or air). Some vehicles use a combination of braking
mechanisms, such as drag racing cars with both wheel brakes and a parachute, or airplanes with both
wheel brakes and drag flaps raised into the air during landing.
Since kinetic energy increases quadratically with velocity (K = mv2 / 2), an object traveling at 10 meters
per second has 100 times as much energy as one traveling at 1 meter per second, and consequently the
theoretical braking distance, when braking at the traction limit, is 100 times as long. In practice, fast
vehicles usually have significant air drag, and energy lost to air drag rises quickly with speed.
Almost all wheeled vehicles have a brake of some sort. Even baggage carts and shopping carts may have
them for use on a moving ramp. Most fixed-wing aircraft are fitted with wheel brakes on theundercarriage.
This article relies largely or entirely upon a single source. Please help improve this article by introducing appropriate citations to additional sources. (July 2008)
A drum brake with the drum removed as used on the rear wheel of a car or truck. Note that in this installation, a cable-
operated parking brake uses the service shoes.
A drum brake is a brake in which the friction is caused by a set of shoes or pads that press against a
rotating drum-shaped part called a brake drum.
The term "drum brake" usually means a brake in which shoes press on the inner surface of the drum.
When shoes press on the outside of the drum, it is usually called a clasp brake. Where the drum is pinched
between two shoes, similar to a conventional disk brake, it is sometimes called a "pinch drum brake",
although such brakes are relatively rare. A related type of brake uses a flexible belt or "band" wrapping
around the outside of a drum, called a band brake.
Components
The Drum Brake has a large number of components depending upon the type of vehicle, in which it is used. Some of the major components of the Drum brake are:
Back Plate Brake Drum Wheel cylinder Brake shoe Springs and pins
The Back Plate serves as the base on which all the components are assembled. It attaches to the axle and forms a solid surface for the wheel cylinder, brake shoes and assorted hardware. Since all the braking operations exert pressure on the back plate, it needs to be very strong and resistant to any wear and tear or corrosion. A good back plate hardly creates any problem. Apart from these parts, Lever for Emergency or Parking brake, and Automatic Brake-shoe adjuster are also present in the brakes of the recent years.
Back plate made in the pressing shop.
[edit]Brake Drum
The brake drum is generally made of a special type of cast iron. It is positioned very close to the brake shoe without actually touching it, and rotates with the wheel and axle. As the lining is pushed against the inner surface of the drum, friction heat can reach as high as 600 degrees F. The brake drum must be:
One wheel cylinder is used for each wheel. Two pistons operate the shoes, one at each end of the wheel cylinder. When hydraulic pressure from the master cylinder acts upon the piston cup, the pistons are pushed toward the shoes, forcing them against the drum. When the brakes are not being applied, the piston is returned to its
original position by the force of the brake shoe return springs. The parts of the wheel cylinder are as follows:
Cut-away section of a wheel cylinder.
Piston Compression spring Dust cap Protective plug Bleed screw Self - locking screw.[edit]Brake shoe
Brake shoes are made of two pieces of sheet steel welded together. The friction material is attached to the Lining table either by adhesive bonding or riveting. The crescent shaped piece is called the Web and contains holes and slots in different shapes for return springs, hold-down hardware, parking brake linkage and self-adjusting components. All the application force of the wheel cylinder is applied through the web to the lining table and brake lining. The edge of the lining table generally has three “V" shaped notches or tabs on each side called Nibs. The nibs rest against the support pads of the backing plate to which the shoes are installed. Each brake assembly has two shoes, a primary and secondary. The primary shoe is located toward the front of the vehicle and has the lining positioned differently than the secondary shoe. Quite often the two shoes are interchangeable, so close inspection for any variation is important.
Linings must be resistant against heat and wear and have a high friction coefficient. This coefficient must be as unaffected as possible by fluctuations in temperature and humidity. Materials which make up the brake shoe include,
Friction modifiers, Powdered metal, Binders, Fillers and Curing agents.
Friction modifiers such as graphite and cashew nut shells, alter the friction coefficient. Powdered metals such as lead, zinc, brass, aluminium and other metals increase a material’s resistance to heat fade. Binders are the glues that hold the friction material together. Fillers are added to friction material in small quantities to accomplish specific purposes, such as rubber chips to reduce brake noise.
[edit]Springs and Pins
The various springs and accompanying components present in the drum brake are as follows,
Spring plate Retaining pin Lower return spring Holder pin Holder spring
The brakes are held against the backing plate by retaining clips and springs. The hold down spring is used to retain the brake shoe in
position in relation to the backing plate. During vehicle operation it keeps the brake shoe in position.
[edit]Automatic Brake Self Adjuster
This Adjuster consists of the following components
Sectional layout showing the push rods, Nut adjuster and Lever pawl.
Push rod male and female Nut adjuster Lever pawl
It is used to adjust the distance between the brake shoe and the drum automatically, in the case of brake shoe wear.
[edit]Working:
[edit]Normal Braking Operation
When you apply the brakes, brake fluid is forced under pressure from the Tandem Master Cylinder (TMC) into the wheel cylinder, which in turn pushes the brake shoes into contact with the machined surface on the inside of the drum. This rubbing action reduces the rotation of the brake drum, which is coupled to the wheel. Hence the speed of the vehicle is reduced. When the pressure is released, return springs pull the shoes back to their rest position.
[edit]Automatic Brake Self-Adjuster
As the brake linings wear, the shoes must travel a greater distance to reach the drum. When the distance reaches a certain point, a self-adjusting mechanism automatically reacts by adjusting the rest position of the shoes so that they are closer to the drum. Here, the adjusting lever rocks enough to advance the adjuster gear by one tooth. The adjuster has threads on it, like a bolt, so that it unscrews a little bit when it turns, lengthening to fill in the gap. When the brake shoes wear a little more, the adjuster can advance again, so it always keeps the shoes close to the drum.
The parking brake (emergency brake) system controls the brakes through a series of steel cables that are connected to either a hand lever or a foot pedal. The idea is that the system is fully mechanical and completely bypasses the hydraulic system so that the vehicle can be brought to a stop even if there is a total brake failure. Here the cable pulls on a lever mounted in the brake and is directly connected to the brake shoes. This has the effect of bypassing the wheel cylinder and controlling the brakes directly.
[edit]Self-applying characteristic
Drum brakes have a natural "self-applying" characteristic, better known as "self-energizing." [1] The rotation of the drum can drag either or both of the shoes into the friction surface, causing the brakes to bite harder, which increases the force holding them together. This increases the stopping power without any additional effort being expended by the driver, but it does make it harder for the driver to modulate the brake's sensitivity. It also makes the brake more sensitive to brake fade, as a decrease in brake friction also reduces the amount of brake assist.
Disc brakes exhibit no self-applying effect because the hydraulic pressure acting on the pads is perpendicular to the direction of rotation of the disc.[1] Disc brake systems usually have servo assistance ("Brake Booster") to lessen the driver's pedal effort, but some disc braked cars (notably race cars) and smaller brakes for motorcycles, etc., do not need to use servos.[1]
Note: In most designs, the "self applying" effect only occurs on one shoe. While this shoe is further forced into the drum surface by a moment due to friction, the opposite effect is happening on the other shoe. The friction force is trying to rotate it away from the drum. The forces are different on each brake shoe resulting in one shoe wearing faster. It is possible to design a two-shoe drum brake where both shoes are self-applying (having separate actuators and pivoted at opposite ends), but these are very uncommon in practice.
Drum brakes are typically described as either leading/trailing or twin leading.[1]
Rear drum brakes are typically of a leading/trailing design(For Non Servo Systems), or [Primary/Secondary] (For Duo Servo Systems) the shoes being moved by a single double-acting hydraulic cylinder and hinged at the same point.[1] In this design, one of the brake shoes will always experience the self-applying effect, irrespective of whether the vehicle is moving forwards or backwards.[1] This is particularly useful on the rear brakes, where the parking brake (handbrake or footbrake) must exert enough force to stop the vehicle from travelling backwards and hold it on a slope. Provided the contact area of the brake shoes is large enough, which isn't always the case, the self-applying effect can securely hold a vehicle when the weight is transferred to the rear brakes due to the incline of a slope or the reverse direction of motion. A further advantage of using a single hydraulic cylinder on the rear is that the opposite pivot may be made in the form of a double lobed cam that is rotated by the action of the parking brake system.
Front drum brakes may be of either design in practice, but the twin leading design is more effective.[1] This design uses two actuating cylinders arranged so that both shoes will utilize the self-applying characteristic when the vehicle is moving forwards.[1] The brake shoes pivot at opposite points to each other.[1] This gives the maximum possible braking when moving forwards, but is not so effective when the vehicle is traveling in reverse.[1]
The optimum arrangement of twin leading front brakes with leading/trailing brakes on the rear allows for more braking force to be deployed at the front of the vehicle when it is moving forwards, with less at the rear. This helps to prevent the rear wheels locking up, but still provides adequate braking at the rear when it is needed.[1]
The brake drum itself is frequently made of cast iron, although some vehicles have used aluminum drums, particularly for front-wheel applications. Aluminum conducts heat better than cast iron, which improves heat dissipation and reduces fade. Aluminum drums are also lighter than iron drums, which reduces unsprung weight. Because aluminum wears more easily than iron, aluminum drums will frequently have an iron or steel liner on the inner surface of the drum, bonded or riveted to the aluminum outer shell.
[edit]Advantages
Drum brakes are used in most heavy duty trucks, some medium and light duty trucks, and few cars, dirt bikes, and ATV's. Drum brakes are often applied to the rear wheels since most of the stopping force is generated by the front brakes of the vehicle and therefore the heat generated in the rear is significantly less. Drum brakes allow simple incorporation of a parking brake. Drum brakes are also occasionally fitted as the parking (and emergency) brake even when the rear wheels use disk brakes as the main brakes. In this situation, a small drum is usually fitted within or as part of the brake disk also known as a banksia brake.
In hybrid vehicle applications, wear on braking systems is greatly reduced by energy recovering motor-generators (see regenerative braking), so some hybrid vehicles such as the GMC Yukon hybrid and Toyota Prius (except the third generation) use drum brakes.
Disc brakes rely on pliability of caliper seals and slight runout to release pads, leading to drag, fuel mileage loss, and disc scoring. Drum brake return springs give more positive action and, adjusted correctly, often have less drag when released.
Certain heavier duty drum brake systems compensate for load when determining wheel cylinder pressure; a feature unavailable when disks are employed. One such vehicle is the Jeep Comanche. The
Comanche can automatically send more pressure to the rear drums depending on the size of the load, whereas this would not be possible with disks.
Due to the fact that a drum brakes friction contact area is at the circumference of the brake, a drum brake can provide more braking force than an equal diameter disc brake. The increased friction contact area of drum brake shoes on the drum allows drum brake shoes to last longer than disc brake pads used in a brake system of similar dimensions and braking force. Drum brakes retain heat and are more complex than disc brakes but are often the more economical and powerful brake type to use in rear brake applications due to the low heat generation of rear brakes, a drum brakes self applying nature, large friction surface contact area, and long life wear characteristics(%life used/kW of braking power).
Although drum brakes are often the better choice for rear brake applications in all but the highest performance applications, vehicle manufactures are increasingly installing disc brake system at the rear wheels. This is due to the popularity rise of disc brakes after the introduction front ventilated disc brakes. Front ventilated disc brakes performed much better than the front drum brakes they replaced. The difference in front drum and disc brake performance caused car buyers to purchase cars that also had rear disc brakes. Additionally rear disc brakes are often associated with high performance race cars which has increase their popularity in street cars. Rear disc brakes in most applications are not ventilated and offer no performance advantage over drum brakes. Even when rear discs are ventilated, it is likely that the rear brakes will never benefit from the ventilation unless subjected to very high performance racing style driving.
[edit]As a tailshaft parking/emergency brake
Drum brakes have also been incorporated on the transmission tailshaft as parking brakes (e.g. Chryslers through 1956), with the an advantage that it is completely independent of the service brakes, but having a severe disadvantage in that when used with a bumper jack (common in that era) on the rear (without proper wheel blocks) the differential's action can allow the vehicle to roll off the jack.
Drum brakes, like most other types, are designed to convert kinetic energy into heat by friction.[1] This heat is intended to be further transferred to atmosphere, but can just as easily transfer into other components of the braking system.
Brake drums have to be large to cope with the massive forces that are involved, and they must be able to absorb and dissipate a lot of heat. Heat transfer to atmosphere can be aided by incorporating cooling fins onto the drum. However, excessive heating can occur due to heavy or repeated braking, which can cause the drum to distort, leading to vibration under braking.
The other consequence of overheating is brake fade.[1] This is due to one of several processes or more usually an accumulation of all of them.
1. When the drums are heated by hard braking, the diameter of the drum increases slightly due to thermal expansion, this means the brakes shoes have to move farther and the brake pedal has to be depressed further.
2. The properties of the friction material can change if heated, resulting in less friction. This can be a much larger problem with drum brakes than disk brakes, since the shoes are inside the drum and not exposed to cooling ambient air. The loss of friction is usually only temporary and the material regains its efficiency when cooled,[1] but if the surface overheats to the point where it becomes glazed the reduction in braking efficiency is more permanent. Surface glazing can be worn away with further use of the brakes, but that takes time.
3. Excessive heating of the brake drums can cause the brake fluid to vaporize, which reduces the hydraulic pressure being applied to the brake shoes.[1] Therefore less retardation is achieved for a given amount of pressure on the pedal. The effect is worsened by poor maintenance. If the brake fluid is old and has absorbed moisture it thus has a lower boiling point and brake fade occurs sooner.[1]
Brake fade is not always due to the effects of overheating. If water gets between the friction surfaces and the drum, it acts as a lubricant
and reduces braking efficiency.[1] The water tends to stay there until it is heated sufficiently to vaporize, at which point braking efficiency is fully restored. All friction braking systems have a maximum theoretical rate of energy conversion. Once that rate has been reached, applying greater pedal pressure will not result in a change of this rate, and indeed the effects mentioned can substantially reduce it. Ultimately this is what brake fade is, regardless of the mechanism of its causes.
Disc brakes are not immune to any of these processes, but they deal with heat and water more effectively than drums.
Drum brakes can be grabby if the drum surface gets light rust or if the brake is cold and damp, giving the pad material greater friction. Grabbing can be so severe that the tires skid and continue to skid even when the pedal is released. Grab is the opposite of fade: when the pad friction goes up, the self-assisting nature of the brakes causes application force to go up. If the pad friction and self-amplification are high enough, the brake will stay on due to self-application even when the external application force is released.
Another disadvantage of drum brakes is their relative complexity. A person must have a general understanding of how drum brakes work and take simple steps to ensure the brakes are reassembled correctly when doing work on drum brakes. And, as a result of this increased complexity (compared to disk brakes), maintenance of drum brakes is generally more time-consuming. Also, the greater number of parts results in a greater number of failure modes compared to disk brakes. Springs can break from fatigue if not replaced along with worn brake shoes. And the drum and shoes can become damaged from scoring if various components (such as broken springs or self-adjusters) break and become loose inside the drum.[edit]
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Close-up of a disc brake on a car
On automobiles, disc brakes are often located within the wheel
The disc brake or disk brake is a device for slowing or stopping the rotation of a wheel while it is in
motion.
A brake disc (or rotor in U.S. English) is usually made of cast iron, but may in some cases be made of
composites such as reinforced carbon-carbon or ceramic matrix composites. This is connected to the
wheel and/or the axle. To stop the wheel, friction material in the form of brake pads (mounted on a device
called a brake caliper) is forced mechanically, hydraulically, pneumatically or electromagnetically against
both sides of the disc. Friction causes the disc and attached wheel to slow or stop. Brakes convert motion
to heat, and if the brakes get too hot, they become less effective, a phenomenon known as brake fade.
The design of the disc varies somewhat. Some are simply solid cast iron, but others are hollowed out with fins or vanes joining together the disc's two contact surfaces (usually included as part of a casting process). The weight and power of the vehicle will determine the need for ventilated discs.[10] The "ventilated" disc design helps to dissipate the generated heat and is commonly used on the more-heavily-loaded front discs.
Many higher performance brakes have holes drilled through them. This is known as cross-drilling and was originally done in the 1960s on racing cars. For heat dissipation purposes, cross drilling is still used on some braking components, but is not favored for racing or other hard use as the holes are a source of stress cracks under severe conditions.
Discs may also be slotted, where shallow channels are machined into the disc to aid in removing dust and gas. Slotting is the preferred method in most racing environments to remove gas, water, and de-glaze brake pads. Some discs are both drilled and slotted. Slotted discs are generally not used on standard vehicles because they quickly wear down brake pads; however, this removal of material is beneficial to race vehicles since it keeps the pads soft and avoids vitrification of their surfaces.
As a way of avoiding thermal stress, cracking and warping of the disc these are sometimes mounted in a half loose way to the hub with coarse splines. This allows the disc to expand in a controlled symmetrical way and with less unwanted heat transfer to the hub.
On the road, drilled or slotted discs still have a positive effect in wet conditions because the holes or slots prevent a film of water building up between the disc and the pads. Crossdrilled discs may eventually crack at the holes due to metal fatigue. Cross-drilled brakes that are manufactured poorly or subjected to high stresses will crack much sooner and more severely.
[edit]On motorcycles
Motorcycle disc brakes have become increasingly sophisticated, partly through marketing. Their discs are usually drilled and occasionally slotted. Calipers have evolved from simple "single-pot" units to 2-, 4- and even 6-pot items. It is debatable whether the modern fashions of "radially-mounted calipers" and "wavy discs" significantly improve braking. Since (compared to cars) motorcycles have a higher centre of gravity:wheelbase ratio, they experience more weight transference when braking. A modern sports bike will typically have twin front discs of large diameter, but only a single rear disc that is very much smaller (or even a small rear drum brake). The front brake(s) provide most of the required deceleration; the rear brake serves mainly as to "balance" the motorcycle during braking. If too much braking force is applied to the rear brake, the rear wheel is liable to lock up; so motorcycles should not have oversize rear brakes.
[edit]On bicycles
See also: Bicycle brake#Disc brakes.
A mountain bike disc brake
Mountain bike disc brakes range from simple, mechanical (cable) systems, to expensive and powerful, 6-pot (piston) hydraulic disc systems, commonly used on downhill racing bikes. Improved technology has seen the creation of the first vented discs for use on
mountain bikes, similar to those on cars, introduced to help avoid heat fade on fast alpine descents. Although less common, discs are also used on road bicycles for all-weather cycling with predictable braking, although drums are sometimes preferred as harder to damage in crowded parking, where discs are sometimes bent. Most bicycle brake discs are made of stainless steel, although some lightweight discs are made of titanium or aluminium. Discs are thin, often about 2 mm. Some use a two-piece floating disc style, others use a floating caliper, others use pads that float in the caliper, and some use one moving pad that makes the caliper slide on its mounts, pulling the other pad into contact with the disc. Because the "motor" is small, an uncommon feature of bicycle brakes is pads that retract to eliminate residual drag when the brake is released. In contrast, most other brakes drag the pads lightly when released.
[edit]On other vehicles
Disc brakes are increasingly used on very large and heavy road vehicles, where previously large drum brakes were nearly universal. One reason is the disc's lack of self-assist makes brake force much more predictable, so peak brake force can be raised without more risk of braking-induced steering or jackknife on articulated vehicles. Another is disc brakes fade less when hot, and in a heavy vehicle air and rolling drag and engine braking are small parts of total braking force, so brakes are used harder than on lighter vehicles, and drum brake fade can occur in a single stop. For these reasons, a heavy truck with disc brakes can stop in about 120% the distance of a passenger car, but with drums stopping takes about 150% the distance.[14] In Europe, stopping distance regulations essentially require disc brakes for heavy vehicles. In the U.S., drums are allowed and are typically preferred for their lower purchase price, despite higher total lifetime cost and more frequent service intervals.
Yet larger discs are used for railroads and some airplanes. Passenger rail cars and light rail often use disc brakes outboard of the wheels, which helps ensure a free flow of cooling air. In contrast, some airplanes have the brake mounted with very little cooling and the brake gets quite hot in a stop, but this is acceptable as the maximum braking energy is very predictable.
For auto use, disc brake discs are commonly manufactured out of a material called grey iron. The SAE maintains a specification for the manufacture of grey iron for various applications. For normal car and light truck applications, the SAE specification is J431 G3000 (superseded to G10). This specification dictates the correct range of hardness, chemical composition, tensile strength, and other properties necessary for the intended use. Some racing cars and airplanes use brakes with carbon fiber discs and carbon fiber pads to reduce weight. Wear rates tend to be high, and braking may be poor or grabby until the brake is hot.[edit]
Suspension (vehicle)From Wikipedia, the free encyclopedia
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The front suspension components of a Ford Model T.
"Turbo" redirects here. For other uses, see Turbo (disambiguation).
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It has been suggested that Superturbocharging be merged into this article or section. (Discuss) Proposed since July 2011.
Cut-away view of an air foil bearing-supported turbocharger made by Mohawk Innovative Technology
A turbocharger, or turbo (colloquialism), is a centrifugal compressor powered by a turbine which is driven
by an engine's exhaust gases. Its benefit lies with the compressor increasing the pressure of air entering
the engine (forced induction) thus resulting in greater performance (for either, or both, power & efficiency).
They are popularly used with internal combustion engines(e.g. four-stroke engines like Otto
cycles and Diesel cycles). Turbochargers have also been found useful compounding external combustion
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All naturally aspirated Otto and diesel cycle engines rely on the downward stroke of a piston to create
a low-pressure area (less than atmospheric pressure) above the piston in order to draw air through
the intake system. With the rare exception of tuned induction systems, most engines cannot inhale
their full displacement of atmospheric density air. The measure of this loss or inefficiency in four
stroke engines is called volumetric efficiency. If the density of the intake air above the piston is equal
to atmospheric, then the engine would have 100% volumetric efficiency. Unfortunately, most engines
fail to achieve this level of performance.
This loss of potential power is often compounded by the loss of density seen with elevated altitudes.
Thus, a natural use of the turbocharger is with aircraft engines. As an aircraft climbs to higher
altitudes the pressure of the surrounding air quickly falls off. At 5,486 m (18,000 ft) the air is at half the
pressure of sea level, which means that the engine will produce less than half-power at this altitude.
The objective of a turbocharger, just as that of a supercharger, is to improve an engine's volumetric
efficiency by increasing the intake density. The compressor draws in ambient air and compresses it
before it enters into the intake manifold at increased pressure. This results in a greater mass of air
entering the cylinders on each intake stroke. The power needed to spin the centrifugal compressor is
derived from the high pressure and temperature of the engine's exhaust gases. The turbine converts
the engine exhaust's potential pressure energy and kinetic velocity energy into rotational power, which
is in turn used to drive the compressor.
A turbocharger may also be used to increase fuel efficiency without any attempt to increase power. It
does this by recovering waste energy in the exhaust and feeding it back into the engine intake. By
using this otherwise wasted energy to increase the mass of air it becomes easier to ensure that all
fuel is burnt before being vented at the start of the exhaust stage. The increased temperature from the
higher pressure gives a higher Carnot efficiency.
The control of turbochargers is very complex and has changed dramatically over the 100 plus years of
its use. A great deal of this complexity stems directly from the control and performance requirements
of various engines with which it is used. In general, the turbocharger will accelerate in speed when the
turbine generates excess power and decelerates when the turbine generates deficient power. Aircraft,
industrial diesels, fuel cells and motor-sports are examples of the wide range of performance
For the Australian rock group, see Intercooler (band).
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It has been suggested that Charge air cooler be merged into this article or section. (Discuss) Proposed since October 2009.
An intercooler (original UK term, sometimes aftercooler in US practice), or charge air cooler, is an air-to-
air or air-to-liquid heat exchange device used on turbocharged and supercharged (forced induction) internal
combustion engines to improve theirvolumetric efficiency by increasing intake air charge density through
nearly isobaric (constant pressure) cooling, which removes the heat of compression (i.e., the temperature
rise) that occurs in any gas when its pressure is raised or its unit mass per unit volume (density) is
increased. A decrease in intake air charge temperature sustains use of a more dense intake charge into
the engine, as a result of supercharging. The lowering of the intake charge air temperature also eliminates
the danger of pre-detonation (knock) of the fuel air charge prior to timed spark ignition. Thus preserving the
benefits of more fuel/air burn per engine cycle, increasing the output of the engine. Intercoolers increase
the efficiency of the induction system by reducing induction air heat created by the turbocharger and
promoting more thorough combustion. They also eliminate the need for using the wasteful method of
lowering intake charge temperature by the injection of excess fuel into the cylinders' air induction
chambers, to cool the intake air charge, prior to its flowing into the cylinders. This wasteful practice (when
intercoolers are not used) nearly eliminated the gain in engine efficiency from supercharging, but was
necessitated by the greater need to prevent at all costs the engine damage that pre-detonation engine
knocking causes.[1]
The inter prefix in the device name originates from historic compressor designs. In the past, aircraft
engines were built with charge air coolers that were installed between multiple stages of supercharging,
[citation needed] thus the designation of inter. Modernautomobile designs are technically
designated aftercoolers because of their placement at the end of supercharging chain. This term is now
considered archaic in modern automobile terminology since most forced induction vehicles have single-
stage superchargers or turbochargers although "aftercooler" is still in common use in the piston engined
aircraft industry. In a vehicle fitted with two-stage turbocharging, it is possible to have both an intercooler
(between the two turbocharger units) and an aftercooler (between the second-stage turbo and the engine).
The JCB Dieselmax land speed record-holding car is an example of such a system. In general, an
intercooler or aftercooler is said to be a charge air cooler.
Intercoolers can vary dramatically in size, shape and design, depending on the performance and space
requirements of the entire supercharger system. Common spatial designs are front mounted intercoolers
(FMIC), top mounted intercoolers (TMIC) and hybrid mount intercoolers (HMIC). Each type can be cooled
with an air-to-air system, air-to-liquid system, or a combination of both.
Exhaust systemFrom Wikipedia, the free encyclopedia
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Exhaust manifold (chrome plated) on a car engine
Muffler and tail pipe on a car
An exhaust system is usually tubing used to guide reaction exhaust gases away from a
controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine
and includes one or more exhaust pipes. Depending on the overall system design, the exhaust gas may
flow through one or more of:
Cylinder head and exhaust manifold
A turbocharger to increase engine power.
A catalytic converter to reduce air pollution.
A muffler (North America) / silencer (Europe), to reduce noise.
Catalytic converterFrom Wikipedia, the free encyclopedia
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Catalytic converter on a 1996 Dodge Ram Van
A catalytic converter (colloquially, "cat" or "catcon") is a device used to reduce the toxicity of exhaust
emissions from an internal combustion engine. Inside a catalytic converter, a catalyst stimulates a chemical
reaction in which noxious byproducts of combustion carbon monoxide, unburned hydrocarbons, and oxides
of nitrogen are converted to less-toxic or inert substances such as carbon dioxide, hydrogen, nitrogen and
oxygen.[1]
First widely introduced on series-production automobiles in the United States market for the 1975 model
year to comply with tightening U.S. Environmental Protection Agency regulations on auto exhaust
emissions, 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, airplanesand
This article is about the exhaust system component. For other uses, see Muffler (disambiguation).
This article may require cleanup to meet Wikipedia's quality standards. (Consider using more specific clean up instructions.) Please improve this article if you can. The talk page may contain suggestions. (July 2007)
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This article may contain original research. Please improve it by verifying the claims made and adding references. Statements consisting only of original research may be removed. More details may be available on the talk page. (March 2011)
Muffler(silver) and exhaust pipe on aDucati 695 motorcycle
A muffler (or silencer in British English) is a device for reducing the amount of noise emitted by
the exhaust of an internal combustion engine. The muffler was originally invented by Milton O. Reeves.[1
Description
Dual tailpipes attached to a the muffler on a passenger car