Brakes issues

Possible clogged airline. Original lines?

 

If its happening with different trailers I would check the tractor protection valve first. That is the valve on the tractor that the hoses to the trailer are supplied from.

 

If the trailer service brakes stay applied when you release the brake pedal and if you pull and release the hand valve this releases the trailer service brakes then replace the hand valve and check the exhaust line to be sure it’s not blocked (not likely). I’ve had this happen more than once.

 

If your tractor brakes are out of adjustment and the trailers are in adjustment. Guess which one is going to work harder and which one is going to work less.

I had the same problem when I first started driving but I pulled the same trailer. Truck got new brakes and drums and adjusters. Problem solved.

Make sure your brakes are good and adjusted. Could rule that possibility out.

 

If it happens with every trailer, common denominator is the truck.

In that case, I would be checking for a sticking valve in the truck's trailer service circuit. If the air won't exhaust from the service line, the trailer brakes will stay applied. The fact that applying and releasing the spike gets them to release tends to support that theory.

 

Abs valve, expensive, leaking break chamber leeking