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Non specific air brake problem


Accelerating Away
Hi Again from Africa,
Sorry to ask a non Land Rover question here but you guys have been so good to me in helping I thought this the only place to help with another problem.
I have a very large truck whose brakes operated on air alone. I have a problem in that when I just touch the brake pedal all is well but when I push down fully the rear brakes lock up and do not release for a minute or so.
I have taken the main "Master cylinder" apart and cleaned thoroughly but this has not solved the problem. Can anyone tell me where to look next.
Thanks again in advance.
Have a look at the rear brakes pipework. You should have a load sensing valve, check that isn't seized.

The other thing to look for is a Brake Relay valve. You might have an air tank at the back, then a flattish valve with large pipes in and out, with a small pipe to the top and a dump valve underneath. This will be after the tank and before the brake chambers.

It is fitted to long vehicles so the brakes work pretty quick and dump the air fast. They stick or get the dump valve damaged.

Something like thse.



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Thanks Chris, Much appreciated, as usual.
I have posted the diagram of the air circuit on www.landyman.com
If you would be kind enough to point me in the right direction I will rip the whole thing apart.
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