Talk:Retarder (mechanical engineering)

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Each section could use its own illustration, for clarity. -- Beland 22:26, 24 May 2007 (UTC)[reply]

This article appears to contradict another article. Please discuss at the talk page and do not remove this message until the contradictions are resolved.

We are talking about several types of engine brakes here and some trucks use some of these types of brakes together. For example; The Ginaf X5376T truck uses a ZF retarder which is like explained earlier, oil hitting a rotor rotating in an opposite direction and thus slowing down the output shaft. It also has the "butterfly" valve in the exhaust pipe which closes when applied, not letting the exhaust gases go out freely, so the engine has to "work" the gases out. And then there is the "Jake" brake. A "jake" brake uses camshafts with a different 3 cammed cam (a normal one is "eggshaped") but this one has two extra "bumps" in them. So what happens; The valve rods are bi-parted with, during normal operation, oil between the two parts and just one of the cams is applied on the exhaust valve (only to let the gasses out) When you apply the jake brake, the oil flows from between the bi-parted rods allowing the two other cams to actuate on the valve rod. So first at TDC the exhaust valve opens to let the compressed air out in order not to allow this compressed air to help the piston go down. The truck will use the rotation coming from the gearbox to bring down the piston. The second step is that when the piston is all the way down, the second cam opens the exhaust valve again in order to let compressed air (from the exhaust pipe with the butterfly valve closed) into the cylinder again. As a result the piston goes up with already compressed air in above it, making it even more difficult and thus creating an amazing braking force. I have tried to write this as easy as possible without any "technical" terms so anyone can understand (I hope) —Preceding unsigned comment added by 201.17.145.130 (talk) 17:17, 26 March 2009 (UTC)[reply]