Trailer Brakes Question

May be old trailer and old designg w/o new style PREV (park release and emergency valve). May be valve is worn and must be repared... cant be sure..

Can you identify trailer valve (with part # on valve dataplate)?

 

I have a 1990 Utility reefer trailer that has been doing the same thing for over a year. At times the brakes set as normal, other times it takes 15 seconds or so. But brakes operate fine and release right away every time.

 

Can you hook up to a different trailer to see if it happens then? That would tell you if it's the trailer or the tractor. My guess is the trailer valve. Unless it has ABS there should be 2 separate valves, 1 for each for each function. All that happens when you press the red valve on on the dash or press the brake pedal ( when the trailer has air) is enough air goes to the trailer to activate the valve to use trailer air to release the parking brakes or activate the service brakes.

Read your post again:

A 96 should have ABS, probably has 1 full function valve that does everything. With the trailer "charged" and tractor parking set, (red button in, yellow out) pull off the the red glad hand. Do the trailer parking brakes apply immediately? They should. If it doesn't, it's in the trailer.

 

I didn't read the above post all the way through, was going to say the same thing

 

Get under the trailer and look at a brake chamber. Find the hose that is farthest away from the slack adjuster, (there are 2 in that are staggered) follow that hose to the valve that is mounted on a tank. That's the parking brake valve. It also will have a 3/8 plastic air line going to the top of it.

If you want to replace the valve;

Take all the hoses off the valve and then unscrew it from the tank.
Depending in how it was assembled, the hoses may only have a swivel at the brake chamber end. If that's the case, all hoses need to be disconnected at the chambers first and then at the valve.

May be a good time to replace all the air hoses while you are under there.

Make sure you don't mix up hose diameters if you replace any hoses. It is super important. Especially on the service side.

Use thread sealer on all pipe ( tapered) threads but not on flare fittings.

Good luck.

 

Make sure you empty air tank first before taking valve off. They do get either a slow leak which releases air overnight takes time to release brakes in morning or won't dump air properly when brakes are applied.

 

Does it only do it with this trailer? When you undone the glad hand did it exhaust quickly and trailer brakes apply ?

 

Good point!