Open main menu
Home
Random
Recent changes
Special pages
Community portal
Preferences
About Wikipedia
Disclaimers
Incubator escapee wiki
Search
User menu
Talk
Dark mode
Contributions
Create account
Log in
Editing
Engine braking
(section)
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
==== Compression release brake ==== [[File:No Jake brakes within city limits.jpg|thumb|No Jake Brake Sign in [[Unadilla, Georgia]]]] A [[Compression release engine brake|compression release brake]] (also known as a Jacobs brake or "jake brake"), is the type of brake most commonly confused with real engine braking; it is used mainly in large diesel trucks and works by opening the exhaust valves at the top of the compression stroke, so the large amount of energy stored in that compressed air is not returned to the crankshaft but is released into the atmosphere. It is a very effective method of braking, creating large amounts of braking force which significantly extends friction brake life β a {{convert|565|hp|abbr=on}} diesel engine can produce up to {{convert|600|hp|abbr=on}} of braking power at 2,100 RPM.<ref>{{Cite web |title=Understanding Tractor-trailer Performance |url=http://electracold.com/CAT.pdf |url-status=deviated |archive-url=https://web.archive.org/web/20220314154105/http://electracold.com/CAT.pdf |archive-date=2022-03-14 |access-date=2023-10-13 |website= |publisher=[[Caterpillar Inc.]] |page=20}}</ref> Normally, during the compression stroke, energy is used as the upward-traveling piston compresses air in the cylinder; the compressed air then acts as a compressed spring and pushes the piston back down. However, with the jake brake in operation, the compressed air is suddenly released just before the piston begins its downward travel (this sudden release of compressed air creates audible sound waves similar to the expanding gases escaping from the muzzle of a [[firearm]]). Having lost the energy stored within the compressed air, there is no "spring back" so the engine must expend yet more energy pulling the piston back down again. This type of brake produces extreme amounts of [[noise pollution]] if there is no [[muffler]] on the exhaust manifold of the engine, loud enough to disturb the surrounding area. Anecdotally, it sounds similar to a [[jackhammer]], however, the [[loudness]] is between 10 and 20 times the sound pressure level of a jackhammer (10 to 13 [[decibel|dB]] greater). Numerous cities, municipalities, states, and provinces have banned the use of unmuffled compression brakes, which are typically only legal on roads away from populations. In Australia, [[traffic enforcement camera]]s are currently being tested that automatically photograph heavy vehicles that use compression braking.<ref>{{cite web|publisher=[[Roads & Traffic Authority]]|year=2007|title= Annual Report 2007|url=http://www.rta.nsw.gov.au/publicationsstatisticsforms/downloads/2007_rta_annualreport_mainbody.pdf|access-date=2008-06-30}}</ref>
Edit summary
(Briefly describe your changes)
By publishing changes, you agree to the
Terms of Use
, and you irrevocably agree to release your contribution under the
CC BY-SA 4.0 License
and the
GFDL
. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.
Cancel
Editing help
(opens in new window)