Hey, does anyone know exactly how to adjust the drive pressure on a 315C Cat? I need to try and adjust the right rev pressure. I was told it is on the drive motor, but all I see on that is what appears to be cross over reliefs. Any ideas? Im MUCH more used to working on Komatsu equipment. Thanks
Kac are you sure its a pressure problem not a pedal adjustment issue.I had a travel issue on my 311 and after much adue looking at my drive motors I found that one pedal was out of adjustment easy fix just recentered the pedal.The pressure isn't adjusted indivdually on the drive motors.it's a relief adjustment on the valve body.If you are only having issue with one motor in one direction. my guess is that its an adjustment issue or that you have a seal failure in the rotary manifold.
Without a serial number, I could be wrong but this applies to most of the Cat HEXs I've come accross. The counterbalance valve on the motor incorporates the cross over reliefs which in turn incorporate the line reliefs. If you only have low power on one motor in one direction, try exchanging the two cross over relief valves on that motor. If the low power goes to the other direction then strip and clean the suspect cross over relief valve.
Freedom On KACs you would notice a lever alignment problem, which I did not pick up on with this unit. Im not saying that that is not the problem however. I will have to pop the under panel off and take a look at how that system is put together. I have been told my a guy from this area that works on them a bit that the symptoms that this unit is having is usually caused by the failure of the relief for that motor/direction and that it is on the drive motor. I cant agree with him yet. The center swivel thing is also an interesting theory. Cmark I have already switched the cross overs and the problem stayed in the same direction on the same track. That is why i was thinking there might be a different relief than what is externally mounted on the drive motor. I think the s/n ends with 0228 which is what you use to get into the monitor and read pressures...
Cat machines go off the serial prefix. A 312C should be either BNN, BWH, CBA, DBF, FDS, CBA or CBT prefix. The 0228 then identifies the machine within that prefix. There is one main relief for all four travel directions. Each side and direction then has it's own crossover/line relief at the motor. The way I would go about troubleshooting the problem is this; 1. Identify which pump drives the right-hand track. Connect a 3500psi pressure guage to each pump outlet in turn and see which pump registers pressure when you operate the RH track. 2. Once you have your guage connected to the correct pump, stall out the problem track motor by jamming an old bucket pin or similar between the sprocket and the track frame and operating the motor in both directions. 3. Hopefully, the pressure will be lower in the direction that you are having problems with. 3A. If it isn't, you need to look for something external dragging on the track. Collapsed idller maybe? 3B. If it is, then the problem is either; 3B1. The crossover/line relief valve. Exchange the two crossover relief valves. Recheck the pressures. If the low pressure has changed directions then repair or replace the faulty crossover/line relief valve. 3B2. The swivel/rotary coupling/centre joint, whatever you call it round your neck of the woods. If the low pressure stays on the same direction after you've exchanged the crossover/line reliefs, then strip and reseal. Good luck.
I have done everything including switching the cross overs. The pressure is about half of what the other 3 directions are (left f/r and right f). The problem always stays on right rev. All other pressures are where they should be (left f/r and right f). Is there a way to prove that the center swivel is bypassing? Maybe I could take the line coming from the control valve and cap it before the swivel and check to see what pressure im getting. Hmm... thanks for getting my brain thinking...
Cap the line going to the motor, it's the easiest. If you put vacuum on the tank it wont be so messy capping below the swivel.
From reading what you've done with pressures...have you ruled out flow? Try swapping the A and B lines at the travel motor and see if the problem goes to the r/f If so, I'd also look at the center swivel. Have you checked the case drain for forward and reverse on that side?
I have not pulled the case drain to see how much bypass is going out it due to the fact that this unit lives on a barge. I have to try and minimize the amount of oil loss which is very hard to do when troubleshooting hyd problems. I dont really think the flow is the problem due to the fact that it can only build 1/2 the pressure it should be. I am starting to agree with the idea of the center swivel. Next time I go out on this unit and do some more troubleshooting, I will let ya's know how I make out.
Yep. You're on to it... You've established that you're losing pressure and the only realistic option left now is the swivel. By blanking the hoses as you suggest and rechecking the pressure, you'll track it down easily. I'd take some ORFS blanking plugs with you next time. I think they'll be either dash12 or dash14.