Brake issue

Does the truck have application pressure gauges? Should just have to press on the pedal and brakes will apply, need more brakes, press it harder.

Without being there to actually see and experience what its doing, I would say it could be an issue with the treadle valve. That's the air valve the brake pedal actuates. If its sticking or (I think WS uses a hanging brake pedal) the linkage is binding or catching something that could cause what you're experiencing.

 

So you just hold the brake pedal steady and the brakes gradually keep applying harder? I'd look at the treadle valve. Its supposed to regulate its outlet pressure based on how hard you press it.

 

Hydraulic breaks? Air n system

 

Adjust your brakes.