daf cf85 hand brake

[BIGWIG74]

im having problems with a slow releasing hand brake on a 06 cf85 8x4 ive changed the 4 way valve/air processing and the relay valve under the nearside step.its ok once it does release just taking a few moments more than our other trucks,if anyone has any ideas it would be appreciated

[Appy]

Has it got a rear relay valve over the axles, sticking maybe.

[BIGWIG74]

Has it got a rear relay valve over the axles, sticking maybe.

thanks for the reply but no ive changed that and the hand control valve

[mooseman16]

firstly do you have springbrakes on the front axle [steer] or not?. whether on front or rear check pressure on park brake relay port 1 [should be over 8 bar system full] put gauge on port 4 of the relay and release handbrake and see how long it takes the gauge to go up to the same pressure as port 1 [should be within 1-2 sec]. if it takes longer there is a blockage or kinked line or possibly faulty hand brake valve. If it is quick then the problem lies from the delivery side [port2] of the park brake relay to the spring brakes. The spring brakes themselves only begin to release between 5,5 and 6 bar so your system pressure needs to be at normal operating level. If you don't come right pm me and I will call you and help

[cav551]

This is only a possibility. You mention changing the air processor. Was this because you could hear a very slow leak probably coming from the middle of the valve between itself and the air drier? If there is a leak elsewhere in circuit 1 (rear service brake) then the air processor will bleed back circuit 3 ( hand brake). Possibly you still have a leak in the rear service brake circuit. DAFs are prone to corroded air tanks particularly with pinholes around the ports and more cheaply weeping drain valves.

[Trickydick]

This is only a possibility. You mention changing the air processor. Was this because you could hear a very slow leak probably coming from the middle of the valve between itself and the air drier? If there is a leak elsewhere in circuit 1 (rear service brake) then the air processor will bleed back circuit 3 ( hand brake). Possibly you still have a leak in the rear service brake circuit. DAFs are prone to corroded air tanks particularly with pinholes around the ports and more cheaply weeping drain valves.

Not seen a rotten daf tank yet, drain taps daily bloody things

[norb]

im having problems with a slow releasing hand brake on a 06 cf85 8x4 ive changed the 4 way valve/air processing and the relay valve under the nearside step.its ok once it does release just taking a few moments more than our other trucks,if anyone has any ideas it would be appreciated

You have a spring brake on axle 2 and 4 ...You changed the 4 way protetion valve because that was a common fault for slow release of the handbrake as there is NRV in the port thinks it port 25 ..im getting old and the memory is failing ..Working on the premise that the braking system has been checked and the caliper are ok ,and no leaks in the system and the other vehicles that releas quicker are also DAFs of about the same age ..

.To release the handbrake you require air ..So you need gauge /gauges to see how long it takes the pressure to build up to release the brakes

You have system pressure to a relay valve ,that gets a signal from the handbrake which passes through a 2 way valve ,never known the 2 way valve be an issue ..So check the air pressure at the relay valve ,you should have system pressure ,if so then what is coming out of port 2s again it should be system pressure ,after that it is the spring brakes...

A small tip remove the silencer from the Load Sensing Valve ,if that can't exhaust quickly it will hold the footbrake side on and give the sympton of a slow to release handbrake

Lastly you have plumbed the APU up correctly with the handbrake to Port 25 ???

[BIGWIG74]

cheers guys i'll try them at the weekend

[finbarot]

Norb, great post.Its so nice to see someone who really knows their onions.Not too many about now sadly, in any trade it would appear.

[BIGWIG74]

Norb, great post.Its so nice to see someone who really knows their onions.Not too many about now sadly, in any trade it would appear.

yeah hes helped me numerous times before when stuck with our dafs hes the man!

[norb]

Norb, great post.Its so nice to see someone who really knows their onions.Not too many about now sadly, in any trade it would appear.

Thank you finbarot ,your comments are very much appreciated..

[Bking]

Norb, great post.Its so nice to see someone who really knows their onions.Not too many about now sadly, in any trade it would appear.

yeah hes helped me numerous times before when stuck with our dafs hes the man!

Well if you say so!!!!!

[norb]

Well if you say so!!!!![/quote]

P.M.S.L

[Own Account Driver]

Norb, great post.Its so nice to see someone who really knows their onions.Not too many about now sadly, in any trade it would appear.

yeah hes helped me numerous times before when stuck with our dafs hes the man!

Well if you say so!!!!!

I do admire your brass neck, if nothing else.

You realise this isn’t a forum for Goldfish as everyone here can probably remember all the absolute clueless crap you’ve posted, over the years, occasionally initially convincing some poor schmucks you know what you’re talking about.

[norb]

Norb, great post.Its so nice to see someone who really knows their onions.Not too many about now sadly, in any trade it would appear.

yeah hes helped me numerous times before when stuck with our dafs hes the man!

Well if you say so!!!!!

I do admire your brass neck, if nothing else.

You realise this isn’t a forum for Goldfish as everyone here can probably remember all the absolute clueless crap you’ve posted, over the years, occasionally initially convincing some poor schmucks you know what you’re talking about.

Hence i just laugh now OAD ..The people on here are not stupid ,well except one or two ..The amount of PMs i get ,asking a question tells me that people trust me ,even if i can't sort them all ,as not all issues can be sorted over the internet ...I wonder how many BKING gets ??? I still like to read his rants about turbos etc ...

[Toddy2]

im having problems with a slow releasing hand brake on a 06 cf85 8x4 ive changed the 4 way valve/air processing and the relay valve under the nearside step.its ok once it does release just taking a few moments more than our other trucks,if anyone has any ideas it would be appreciated

I had this self same problem on an ERF EC11, we replaced the multi-circuit valve, the air dryer, had the compressor to bits, the hand brake valve, drained and cleaned the tanks and the airlines, checked pressures at various points - It was driving me crackers. Next we replaced the R6 relay valve on the crossmember in front of the drive axle.

Had already tested the non-return valve the feeds this, and it seemed ok. On a closer inspection, we took it to bits and found a 'mushroom shaped' rubber seal that was mis-shapen, This was working on a hit & miss basis - replaced this and all was fine

All that grief, head scatching, swearing & cussing for a simple little valve

[biggriffin]

On xf"s a slow releasing handbrake, sometimes signalled that the air-dryer was on the way out.

[ml9c]

I have the same problem with the hand brake slow to release, changed air dryer unit and no better. Any ideas?

[cav551]

Yes, carry out the test procedures already mentioned.