Ha Ha, very droll & good point. As usual I got my facts slightly askew, Jake brakes:
They shut off fuel supply to the cylinder, and the motor becomes a 6 cylinder air compressor. The built-up air is what slows a semi truck down, without using brakes. The main concept is: When the cylinder is coming back up on the compression cycle, towards the TDC the jake will open the exhaust valve and let out all the compressed air. Thats why the truck makes a loud rumbling sound. Then it closes before the piston reaches TDC comes up and starts going down again. Then on the normal exhaust cycle, there is little to no air to release.
And what this has to do with changing a forum name is beyond me - but this is the "Off Topic Chit Chat" & I sure got off the topic!
Cheers ... Mark
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