Exhaust brake

Since diesel engines lack a throttle valve on the intake manifold, there is no intake vacuum when the engine is not fueling. The intake vacuum creates the slowing effect felt in gasoline engines when they are going down a hill with the foot off the gas. Many different strategies are used on diesels, the least expensive (and also one of the least powerful) of which is the exhaust brake.

Operation

Exhaust brakes are manufactured by many different companies, including competitors Pacbrake, GT, Jacobs and Banks Power. The brakes vary in design, but essentially operate by closing off the exhaust path from the engine, causing the exhaust gases to be compressed in the exhaust manifold, and in the cylinder. Since the exhaust is being compressed, and there is no fuel being applied, the engine works backwards, slowing down the vehicle. The amount of negative torque generated is usually directly proportional to the back pressure of the engine. More advanced exhaust brakes have exhaust pressure modulation (EPM) that controls the back pressure which in turn improves the braking performance across a range of engine speeds.

Performance

Some new innovations increase the exhaust back-pressure by various means, leading to more torque at the flywheel, and therefore more braking power. Braking effectiveness is measured in units of power and is about 60 to 80% of the engine's maximum power output. More performance is usually easily had by down shifting the vehicle (increasing the leverage , or gear ratio of the engine over the wheels).

See also Jake brake.

Legal implications

Compression braking, a form of engine brake, produces excess amounts of noise pollution in comparison to exhaust brakes. For this reason, some vehicle original equipment manufacturers prefer to use exhaust brakes, even when the performance is not as good, just because of the noise issues however combination of an exhaust and compression brakes increases their effectiveness while significantly cuts back on noise pollution.

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

References

* [http://www.bankspower.com/tech_howexhaustbrakeworks.cfm Banks Power exhaust brake page]
* [http://www.pacbrake.com/index.php?page=mechanics PacBrake exhaust brake mechanics]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Exhaust — may refer to:In mathematics: *Proof by exhaustion, proof by examining all individual cases *Exhaustion by compact sets, in analysis, a sequence of compact sets that converges on a given set *Collectively exhaustive, in probability and set theory …   Wikipedia

  • Exhaust gas — A diesel powered truck emits a large amount of exhaust gas while starting its engine. Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel fuel, fuel oil or coal. According to the… …   Wikipedia

  • Compression release engine brake — Jacobs Engine Brake Division logo. A vie …   Wikipedia

  • Jake brake — is a trademark for vehicle retarding systems, or engine brakes, developed and manufactured by Jacobs Vehicle Systems, Inc. The trademark JAKE BRAKE should not be used to refer to engine brakes in general. An engine brake is a braking system used… …   Wikipedia

  • Railway air brake — Piping diagram from 1920 of a Westinghouse E T Air Brake system on a locomotive …   Wikipedia

  • Railway brake — A traditional clasp brake: the brake shoe (brown) bears on the surface (tyre) of the wheel (red), and is operated by the levers (grey) on the left …   Wikipedia

  • Emergency brake (train) — This article is about emergency brakes on trains. For emergency brakes in cars, see hand brake. Driver s brake handle in a UK Electric Multiple Unit On trains, the expression emergency brake has several meanings: The maximum brake force available …   Wikipedia

  • New York Air Brake — NYAB redirects here. For other uses, see NYAB (disambiguation). New York Air Brake Type Privately Held Company Founded 1890 Headquarters Watertown, New York USA …   Wikipedia

  • Counter-pressure brake — The counter pressure brake (German: Gegendruckbremse), also named the Riggenbach counter pressure brake after its inventor, Niklaus Riggenbach, is a dynamic railway brake on steam locomotives that, through a combination of means, brakes the… …   Wikipedia

  • Countersteam brake — A countersteam brake is a brake on a steam locomotive that uses the engine (specifically the cylinders) to help brake the locomotive. It uses the working principle of steam cylinders fitted with slide or piston valves such that, by changing the… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.