Hi all, I have a Case 621C serial number JEE124576. I have lost all hydraulic controls. The machine has no pilot pressure to the joysticks. When the hydraulics quit the bucket was in the air, and it won't even allow me to lower it. Through my research it looks related to the combination valve, but I can't find any information as to what would fail within that valve to prevent pressure from traveling to the joysticks. Does anyone know how the fluid passes through the combination valve, and what could fail to prevent any pressure whatsoever to reach the controls? i have checked the pressure at the main and secondary pumps, and they all are within spec. Steering and everything else functions properly. Any information would be greatly appreciated. Thanks
It wont lower or anything else without pilot pressure The most common problem I've seen is the pilot pump itself. I have seen a few twist the shafts off at the splines. You really need to see if you have any fluid movement before you go off and start screwing with any valves. I'm confused as to what your checking here. Without pilot pressure you cant check main pressure because you have no movement of the main spools to bottom any function out. Brake pressure you could check, which is off the pump that is driven off the engine timing cover on the right side of the machine. SO....where are the pumps located that you are able to check pressures on? Lastly, does the machine go into transmission gears normally? The reason I ask is, that model used a piece of S&^T fiber drive ring that was fitted to a steel toothed flywheel. Those fiber drive rings were famous for stripping the teeth off and leaving you dead in the water. If this is what happened, you will have no hydraulics and no transmission drive.