546 Valmet forwarder parking brake

[Treecuttermo]

Does anyone have a parts breakdown of the parking brake on the front of the bogie axel? Or know how to manually release the brake. 

I'm having an issue where the parking brake will release but after you drive it for 10-15 minutes it will start dragging and the longer you work it or the hotter the fluid gets the worse it drags. If you let it sit and cool back down it will release again for a few minutes and does the same thing. 

I have 450 psi at the brake and I'm assuming that the piston has some bad seals that are allowing the fluid to bypass once the fluid heats up. 

[Gary_C]

You need to get a manual with a pressure setting guide for the brake circuits to properly diagnose any problems in the two brake circuits on that machine. Those two brake circuits are spring applied (normally applied) and pressure released with an accumulator that is charged and recharged when the engine is running. It's a somewhat complicated system that is run off the auxiliary valve bank on the machine. 

There are two parking brake release bolts (the ones with lock nuts) on either side of the bogie housing but they are supposed to be used for emergencies only to move a dead machine.