I have a 331 that has a thumb on it. I am having my breaker fit to the machine. I know i can only use one at a time, will I have to adjust the pressure when I switch to breaker? Do I need a oil return line to prevent overheating with breaker?
Not sure about a 331, but many Bobcat excavators have a switch in cab to select breaker operation. If you're machine doesn't have that, typical single acting auxiliary hyd circuits have pressure line go down pipe on left side of boom and return on pipe on right side of boom. The return must bypass main control valve and instead tap into a tank return line, preferably the line going into oil cooler so oil from breaker will be cooled before returning to tank. It may not be an issue on a small machine like a 331, but on larger excavators you have to not only adjust pressure to suit breaker specs, but you have to make sure flow (gpm) to hammer isn't either excessive or lacking enough flow. About all breakers I've worked on give a "working pressure" spec, that's not the auxiliary circuit relief valve pressure value, the relief valve should be adjusted 600-800 psi above working pressure.
If it's the factory setup and your operating a hydraulic thumb your all set, ready to go. No adjustment .You only need the 2 lines.
x2 I have a 2005 334 with a thumb. Had a breaker on it many times. Just the 2 lines and go to work