Brake problem

Had a similar issue on a couple of our Heil tanks. They were equipped with a Bendix ABS controller with roll stability. The dealer where we bought them suggested replacing the controller with a Wabco brand. They said they'd seen numerous issues with the Bendix controllers and that Bendix no longer would cover the repairs under warranty, not would they do anything to correct the problem.

We did as they said, and the problem went away.

 

Ugh.

Find another trailer. IF you are able. Those trailers need to be stable.

Im sorry I cannot offer you much more but all of my tanks never misbehaved the way you described. Locking is unacceptable unless it is in extremis no #### emergency and even then ABS should kick in and loosen it.

 

"Often times I can feel the trailer let up on the brakes, then grab again hard, and repeat."

That is the ABS working. Does it do this loaded and empty?
Check the tandem weight on a split scale. If I run my trailer low with a light load it will let the ABS engage do to not enough load on the front axle.My DD has a lot of arch and factory ride height adjustment and first time I ran it low with little weight on the trailer the ABS kept actavting until I rasied the trailer and put more weight on the front axle.
You suspension may be shifting weight off of one axle causing ABS to come on. Air ride or spring?
If air ride look a bag height, should be the same, Spring ride may need rebushed.

 

ABS works incredibly fast to keep the wheel rotating. Usually having activated it a few times in both a car and big truck (The car was a interesting situation bear with me) there is a great deal of buzzing going on as the system works to keep you turning until you get slow enough to input perhaps emergency steering to get out of a collision.

I ran my olds 98 off once and the right front hit gravel I got on the brake to settle it down and three wheels was on pavement while the right front ABS activated. That was interesting Then the right rear hit the gravel and activated. Call it lesson in ABS work.

Don't forget if everything is going against you and life is on the line you still have your red and yellow springs to pull. It will lock you down like that. *Snaps. ABS be ######.

 

Further to the ABS comments, a lot of control & relay valves LOOK the same, but can have different "cracking" pressures. Many mechanic's ( & parts folks) replace w/o checking, hence driveability problems. Replace a 15lb. valve with a 5lb. and you have a problem.

 

I remember back when they first started putting ABS on logging trailers. A relative bought a brand new tridem pole trailer and it only had ABS on the front 2 axles. He found that the rear axle was eating tires faster because it would lock up from time to time because it had no ABS. He ended up having the system retrofitted for ABS on all 3 axles.

 

We had a rash of bendix abs valves go on fairly new trailers .. It was almost impossible to stop quickly from a slow speed without hopping the trailer wheels if empty .. Once you made 3 or 4 applications and got a bit of heat in the drums it was almost normal

 

Mexico