Cat 287b Track loader hydraulic problem

My right track will not rotate forward or reverse. My boom & bucket works (raises, lowers, tilts ).The left track rotates fine. Any suggestion on how to trouble shoot the right drive? Thier are 2 big hoses and 2 small hoses can anyone explain which does what and how to test with a gauge? Thanks

I had the same problem, how many hrs?? big ones are your main flow should have 5000 psi the other 2 is a break I believe. I would first check your hydro oil filter see if theres any brass cut it open. next best thing check your relief valves on the pump.