It has been suggested that Exhaust brake be merged into this article or section. (Discuss)

It has been suggested that Jake brake be merged into this article or section. (Discuss)

It has been suggested that the section Other applications from the article Air brake (rail) be merged into this article or section. (Discuss)

Engine braking is the act of using the energy-requiring compression stroke of the internal combustion engine to dissipate energy and slow down a vehicle. Compression braking is a common legal term for the same mechanism. Large trucks use a device called a jake brake to increase the effectiveness of engine braking. Image File history File links Please see the file description page for further information. ... // Preamble Since diesel engines lack an intake manifold, there is no intake vacuum when the engine is not fueling. ... Image File history File links Please see the file description page for further information. ... -1... Image File history File links Please see the file description page for further information. ... Piping diagram from 1920 of a Westinghouse E-T Air Brake system. ... Piping diagram from 1920 of a Westinghouse E-T Air Brake system. ... A colorized automobile engine The internal combustion engine is a heat engine in which the burning of a fuel occurs in a confined space called a combustion chamber. ... -1...

Design

Most four stroke internal combustion engines require compression of the fuel-air mixture before ignition, in order to extract useful mechanical energy from the expansion. Diesel engines are adiabatic and have no spark plugs and use energy transferred to air charge during compression to directly ignite the mixture when the fuel is injected. The four-stroke cycle (or Otto cycle) of an internal combustion engine is the cycle most commonly used for automotive and industrial purposes today (cars and trucks, generators, etc). ... Diesel or Diesel fuel is a specific fractional distillate of fuel oil (mostly petroleum) that is used as fuel in a diesel engine invented by German engineer Rudolf Diesel. ... This article covers adiabatic processes in thermodynamics. ... This article or section should include material from Spark gap A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed aerosol gasoline by means of an electric spark. ...

Regardless of engine type, compression of gas and vapor requires energy as described by theories in physical chemistry and thermodynamics. Compression in an engine is driven by the flywheel). So, the engine ends up converting energy that was formerly kinetic energy of the vehicle into heat in the fuel-air mixture. These hot gasses are exhausted from the vehicle and heat is transferred from engine components to the air. Physical Chemistry is the combined science of physics, chemistry, thermodynamics, and quantum mechanics which functions to provide molecular-level interpretations of observed macroscopic phenomena. ... ‹ The template below has been proposed for deletion. ... Spoked flywheel A flywheel is a heavy rotating disk used as a repository for angular momentum. ... Kinetic jkljfkdffmdklcjenergy (SI unit: the [[klof its motion. ... In physics, heat is defined as energy in transit. ...

Advantages

The advantage of using the engine to dissipate energy is this immediate ejection of energy. Hot gasses are ejected from the vehicle very quickly and the gasses also transfer much of their heat directly to engine parts. In addition, friction produced within the engine system also adds heat to the engine parts.

This engine heat is taken away by the engine's integrated cooling system: usually a liquid circulation system and a radiator. Disc or drum brakes have no such energy dissipation mechanisms. They must rely on air flow to remove heat and they use their mass to retain heat without producing temperatures that would deform and damage the brakes. Radiator is a common term for several types of heat exchangers. ... Close-up of a disc brake on a car On automobiles, disc brakes are often located within the wheel The disc brake is a device for slowing or stopping the rotation of a wheel. ... A drum brake is a brake in which the friction is caused by a set of shoes or pads that press against the inner surface of a rotating drum. ...

Placing a vehicle in a low gear causes the engine to have more leverage (mechanical advantage) on the road and the road to have less leverage on the engine. This is what allows cars to slow down using their relatively flimsy engine parts. The engine maintains a high rotational speed to dissipate a lot of power without forcing too much strain on the engine. Leverage is related to torque; leverage is a factor by which lever multiplies a force. ... In physics and engineering, mechanical advantage (MA) is the factor by which a machine multiplies the force put into it. ... Leverage is related to torque; leverage is a factor by which lever multiplies a force. ...

The jake brake is required in large diesel vehicles because the rate of conversion of mechanical energy into waste thermal energy is low compared to the mechanical returns to kinetic energy from the air-spring effect in the engine.-1...

Applications

Engine braking is always active in all non-hybrid cars with an internal combustion engine, regardless of transmission type. Engine braking passively reduces wear on brakes and helps a driver maintain control of the car. It is always active when the foot is lifted off the accelerator, the transmission is not in neutral, the clutch is engaged and a freewheel is not engaged. This is often called engine drag. Honda Insight, a hybrid gas-electric vehicle 2004 Toyota Prius, a hybrid gas-electric vehicle A hybrid vehicle uses multiple energy sources or propulsion systems to provide motive power. ... Freewheel mechanism In mechanical or automotive engineering a freewheel is a device in a transmission that disengages the driveshaft from the driven shaft in the case that the driven shaft would rotate at a higher rpm than the driveshaft. ...

Active use of engine braking (shifting into a lower gear) is only advantageous when it is necessary to control speed while driving down very steep and long slopes. It should be applied after regular disk or drum brakes have been used to reduce speed to the desired speed. The desired speed is maintained by using engine braking to counteract the acceleration due to gravity.

Improper engine braking technique can cause the wheels to skid, especially on slippery surfaces such as ice or snow, as a result of too much deceleration. As in a skid caused by over-braking, the car will not regain traction until the wheels are allowed to turn more quickly; the driver must reduce engine braking (shifting back up) to regain traction.

The above was confusing to me. I did my search because I wanted to know why signs said "no engine brake". I found the answer on other web pages published by a manufacturers of engine brakes. I would include the links, but am scared off by copyright concerns. The answer is that engine brakes are all about back pressure from restricting the exhaust, and only work on deisel engines.

Downshifting slows a vehicle, but is not related to the "no engine brake" signs, and I doubt can be considered an engine brake.

Legal implications

Compression braking, a form of engine braking, produces extreme amounts of noise pollution if there is no muffler on the exhaust system of the engine. Noise pollution is unwanted human-created sound that disrupts the environment. ... A muffler (USA name) or silencer (name in the United Kingdom and other areas) is a device for reducing the amount of noise emitted by a machine such as an internal combustion engine or a gun. ...

Use of a jake brake produces similar effects, due to release of compressed gasses, but the mechanism is distinct from regular car engine braking.

Anecdotally, it sounds similar to a jackhammer, however the loudness is between 10-20 times the perceived loudness of a jackhammer. A portable jackhammer being used to break up a roadsurface in roadworks. ... Loudness is the quality of a sound which is high in volume (amplitude, or sound pressure). ...

Numerous cities, municipalities, states, and provinces banned the use of unmuffled compression brakes.

See also: List of communities that prohibit engine retarder brakes

See also

Retarder (mechanical engineering) A retarder is a device used to augment or replace some of the functions of primary friction-based braking systems of (usually) heavy vehicles. ...

External links

• City of Vancouver, Washington, U.S.A. trucking regulations