1985 Kenworth W900B

Bigash

New Member
Just bought a 1985 Kenworth W900B. As i live in the UK we dont see many of your great trucks over here. I got this as a toy to restore and show. I have a couple of questions. 1 The engine is a Cat and only has a one position engine retard switch on the dash unlike the two position jake brake switch i am used to. This doesnt seem to do much, any ideas welcome. and 2 we have a different park brake set up to you so could someone explain the Red,Yellow and Blue park brake knobs i have in mine. Thanks.
 
I can't help you with the engine brake question on your cat, as most I have seen here actually have 3 positions, but here is the scoop on the old style 3 button system:

Blue is truck/tractor parking brake only.

Yellow will apply both truck/tractor and trailer parking brakes.

Red is the supply button for the trailer. Push it in to release trailer brakes and supply air to the trailers system.
 
The "Jake Brake" is just the older single stage type that they used to have. In the early days a "Jake" on a CAT was almost worthless and did little more than make a little noise, I had a 3406B with a jake on it and was never too impressed with it.
I alway liked the 3 button system for the parking brakes although the same thing can be accompliushed with a 2 button system by keeping your thumb on the red while pulling the yellow.

Those older KW 900's are cool trucks....But then again, so are the newer ones!
 
1985 Kenworth W900B.

The "Jake Brake" is just the older single stage type that they used to have. In the early days a "Jake" on a CAT was almost worthless and did little more than make a little noise, I had a 3406B with a jake on it and was never too impressed with it.
I alway liked the 3 button system for the parking brakes although the same thing can be accompliushed with a 2 button system by keeping your thumb on the red while pulling the yellow.

Those older KW 900's are cool trucks....But then again, so are the newer ones!
Just like to say a big thanks to you guys for answering my questions.
 
The Jacobs Engine Brake functions by holding the exhaust valves open when the piston would normally be compressing the air/fuel intake charge, preventing the engine from producing positive power.

There are settings that need to be maintained to ensure proper engine brake performance. It is similar to performing a valve adjustment.

Do a web search for Jacobs Engine Brake Adjustment, and you should find pdf versions of the service manuals for this.

It has been a ling time since I did any of this kind of work, but I think there are also some gages and setting tools available to make the job easier to perform. And when they are adjusted properly they will perform at their best, but as BW9 pointed out, they didn't work as well back then.

The engine brake systems on today's modern electronic engines work much better than the original Jacobs Engine Brake. Also, the name "Jake Brake" has become synonymous with all engine brakes, and many people call the engine brake on their truck a "jake" even though it may not a Jacobs Engine Brake. I have not seen an actual Jacobs Engine Brake on any of the newer electronic engines, save for an early Detroit DDEC Series 60 engine. I think that the Cummins N14 engines could be fitted with them too.

I have even heard guys talking about putting "jakes" on their Dodge pickups with the ISB Cummins engine, but all those are is a mechanical valve that blocks the exhaust pipe downstream of the turbocharger.
 
The older "Jacobs Brake" worked very well on a Cummins....It didn't work worth a damn on a CAT or a Detroit. The C-Brake on my N-14 works very well also...The last CAT I had for any length of time was a 3406B and the jake Breke on that didn't do much of anything except make a little noise.
 

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