2002 Link Belt 2800Q - I think it's the same as a Case 9030B or a SH200-3. It's a KYB MAG-170VP-3400 travel motor. I think Volvo EC210 and other 200 class machines use the same, or similar motor. Classic weak travel motor: machine moves in an arc when travelling straight. Weak side can barely turn the machine by itself. Applying third function in straight line travel, causing pump flow to merge does not change anything. Swivel/rotary joint just got rebuilt. Fixed my leaks, but travel still weak. Finally did the case drain test. My manual doesn't give a spec for case drain, just says compare the two sides. Roughly in 30 seconds, approx 1.75L on good side, and 2.5L on bad side. There is a certain amount of error in the measurement with the hose dribbling away between tests. But the weak side seems to be putting out more. Pump shows 4300psi with track stalled on the bad side. Within spec, but low. Interestingly, you can hear fluid bypassing within the bad travel motor. Not so on the good side. So what's the next step? Just based on the sound of the bad motor, I think there is something wrong with the motor. If it were bad counterbalance or relief, it should still have a good case drain test? It HAS to be a worn block/piston/valve plate? Anyone got a recommendation for sketchy aftermarket parts? Or any further testing? I'm hoping I can tear into it without full remove or touching the final. Like this guy did:
The guy in the video changed out the seal that leaks hydraulic oil into the opposite side planetary. If yours is failing case drain, it is probably quite worn out inside. You could bye from China, but there is good and no good junk coming from there. Some suppliers have done the homework, so they can supply quality stuff. Where I work they bought looks exactly perfect exhaust manifolds from there, through a US broker. In the end no money back and threw it all in the garbage. $2500 Not much if you say it fast. Simon C
I hear you Simon: Chinese parts can be a gamble. Worse case, it's a 100% waste of money. I thought the video was interesting as it shows a total in-place reassembly of the travel motor. It doesn't seem overly difficult. The hardest part is finding quality parts. Anyone have any input on my diagnoses? Anything else I'm overlooking? I feel like the next step is teardown and inspection of the travel motor. But I'd like to do as much testing first as possible.
I think if you've got much higher case drain oil on one side it pretty much points to the motor, especially if you can hear it bypassing.
if the problem on the valve plate - it will not be dropping pressure too much while not moving, she’ll leak like a sieve when she does move.