Editing Compression release engine brake (section)

{{Short description|Mechanism of some diesel engines}}
[[File:Jake Brake.jpg|thumb|A compression release engine brake from Jacobs Vehicle Systems, popularly known as a "Jake brake"]]
[[File:Unit injector.jpg|thumb|A view of engine compression brake rocker arm (the thinnest arm at the left of each set)]]
[[File:Jacobs engine brake division badge 001.jpg|thumb|Jacobs Engine Brake Division logo]]

A '''compression release engine brake''', '''compression brake''', or '''decompression brake''' is an [[engine braking]] mechanism installed on some [[diesel engine]]s. When activated, it opens [[4-stroke cycle engine valves#Internal combustion engine|exhaust valves]] to the cylinders, right before the compression stroke ends, releasing the compressed gas trapped in the cylinders. The compression followed by the "wasteful" release consumes great amount of energy, effectively slowing the vehicle.

[[Clessie Cummins]] was granted a patent for the engine compression brake in 1965, and the first company to manufacture them was [[Jacobs Vehicle Systems]].<ref>{{cite patent |country=US |number=3220392 |status=patent |title=Vehicle engine braking and fuel control system |pubdate= |gdate=November 30, 1965 |fdate=June 4, 1962 |pridate= |inventor-last=Cummins |inventor-first=Clessie L. |inventor-link=Clessie Cummins}}</ref><ref>{{Cite web |url=http://files.asme.org/ASMEORG/Communities/History/Landmarks/5577.pdf |title=Jacobs® Engine Brake Retarder |date=October 17, 1985 |publisher=[[The American Society of Mechanical Engineers]] |url-status=dead |archive-url=https://web.archive.org/web/20110816064603/http://files.asme.org/ASMEORG/Communities/History/Landmarks/5577.pdf |archive-date=2011-08-16 |access-date=2010-04-30}}</ref>  Therefore, the brakes are commonly known as '''Jake brakes'''.