Hi our Volvo a35d is struggling to hold brake pressure to the rear after a couple hours of running, it’ll drop while your sitting to get loaded and a little rev builds it straight back up, the front is holding pressure fine, I’m thinking it could be something as simple as a unloading/relief valve serial number is a35dv11947, Thanks again for any help
I had a similar issue and it was the park brake. When stopped with the brake applied it was leaking air, when I was moving it was fine as there was no air going to that circuit then.
Are you using the load/dump brake? Are you losing hydraulic pressure? Is your axle oil gaining?
Yes tipping brake is getting used (button to the left of the tip lever) and the pressure is dropping once warm, and not gaining oil in axle no