List:
My understanding of the Jake Brake is minuscule, but when we refer to
compression braking, I think what we really mean is vacuum braking.
The following is an excerpt from how stuff works...
"Compressing the air in the cylinder takes power. If the engine's drive
shaft is turning the engine to brake the truck, the power used to
compress the air is braking power. However, that power is stored in the
cylinder, so if you let it, the compressed air simply pushes the piston
back down. Therefore, you don't really get any braking at all from the
compression stroke on an unmodified engine.
A Jake Brake modifies the timing on the exhaust valves so that, when
braking is desired, the exhaust valves open right as the piston reaches
the top of the compression stroke. The energy gathered in the compressed
air is released, so the compression stroke actually provides braking
power."
I have been taught that the diesel, has little, if any off-throttle
resistance from the engine. This is because the engine always has all
the air it can take in and no vacuum build up at closed throttle since
the throttle controls fuel, not air. And there is really little braking
from compression on, even in a gas engine because...
"that power is stored in the cylinder, so if you let it, the compressed
air simply pushes the piston back down."
So possibly there may be something to gain from the compression brake in
the gas engine. (Of course, another of the enemies of the decel braking
that we used to enjoy is the ever higher rear gear ratios.)
I have to say that I am not a lover of diesels, I have not studied
diesel extensively nor have I driven them much. Really, I don't even
like them. They stink, they rattle, and they _______ !!!
All the above is gain from observation, education and a sprinkle of
personal opinion and has no reflection on any of you diesel fans, just
my humble opinion!
Tom, Redding CA - #216 D/CC
/// unsubscribe/change address requests to majordomo@autox.team.net or try
/// http://www.team.net/mailman/listinfo
/// Archives at http://www.team.net/archive/land-speed
/// what is needed. It isn't that difficult, folks.
|