A compression release engine brake, compression brake, or decompression brake is an engine braking mechanism installed on some diesel engines. When activated, it opens exhaust valves to the cylinders,
A compression release engine brake from Jacobs Vehicle Systems, popularly known as a "Jake brake"
A view of engine compression brake rocker arm (the thickest at the right of each set)
Jacobs Engine Brake Division logo
No Jake brakes sign
Clessie Cummins
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Clessie Lyle Cummins was the founder of the Cummins Engine Co. He was an entrepreneur who improved on existing diesel engines, created new diesel engine designs, was awarded 33 United States patents f
Compression release engine brake
…gas trapped in the cylinders. The compression followed by the "wasteful" release consumes a great amount of energy, effectively slowing the vehicle. Clessie Cummins was granted U.S. patent 3,220,392 for the engine compression brake in 1965. The first company to manufacture them was Jacobs Vehicle Systems, resulting…
Cummins (left) showing Fred Duesenberg one of his engines