Hello, I have a Komatsu PC75UU-3, I was using it today and had the boom down and was rotating/ slewing the bottom by rotating the tracks in either direction and turning the body, when the machine stopped working and an odd noise is coming from the pump area, so I shut the machine down. now when started the odd noise is still there and no functions work ( blade, boom or drive ), I see these units have 2 pumps, main for boom and travel, one for swivel and blade, but nothing is working. Any ideas where to start? I have downloaded the service manual. Cheers Gordon.
I have been reading the service manual, and from what I can see the main pump supplies pressure to the self-pressure reducing valve ( which supplies regulated pressure to the actuators ), I have loosened PR ( output on PR valve ) and no fluid comes out, so undone main pump outlet and no pressure from that either. Would this indicate that the Main pump is faulty? time to get my hands dirty?
I have removed the main pump, the coupling, shaft and bearing are damaged. see pictures below.
The bearing race had collapsed, and the ball bearings were jamming in the housing, the shaft was spinning in the Coupling. Parts are $845 NZD ( $518 USD ) from Komatsu, or $68 USD from China
Pump was a bit tricky to get out, but at least I didn't need to remove the 1.1 Ton counterweight, best idea to remove the smaller gear pump off the end first, I have the service manual and full parts list if anyone requires them, PM me. Cheers Gordon.
Thanks for the detailed follow up post and pictures. I think I’m having the same problem with same machine. Safety switch on armrest and safety solenoid are working. Loosened the 4 bolts holding main pump output hose and have no discharge from main pump output while running machine with safety armrest down. No hydraulic pressure at joysticks and no hydraulic function. Machine is broke down in middle of road blocking access to property so hopefully can work it out quickly. If you can give me any more info it’d likely help me along. I have service manual already.
is it making a bit of an odd noise? youll have to take the pump off, if it's the same problem, quick fix, weld the 2 coupling to the flywheel , it will work.
It seemed like perhaps it was making a little bit of whining noise when it first stopped functioning. Also there was some little bits of shattered plastic stuck in the hydraulic oil filter, maybe 3mm long. Hoping pump itself isn’t damage but not optimistic. That’s an interesting idea, But don’t have access to power for welded and not thrilled of the idea not fixing it correctly. I’ve pulled engines hood, hydraulic tank body panel , air filter housing, muffler. Don’t have other equipment here to lift counterweight off, would have to rent $$$. So I’m hoping I can remove main pump without removing counterweight, like you said. Is there any specific advice you can give me to get pump out without removing counter weight? We’re you able to lift the main pump out by hand?
I took off the gear pump and then just heaved the main pump by hand. The main pumps input shaft is stripped as well as the inner diameter spline on the collar support bearing thing. Trying to figure out if I can source a main pump shaft, used main pump, if I will be able to replace the shaft. Not coming up with anything so far. As Gordon suggested Might end up taking pump to local shop and welding main pump to coupler. Seems I have little to loose by doing so and could save a lot of headache time and money.
Glad to hear you got the main pump out ok, yes it is heavy, I used a Aluminum Ladder and braced it to the body of the digger, then used 1500kg tie downs to winch it up and out of the engine bay. My main pump shaft was OK, so just needed new coupling and flywheel plate ( off ali express ). Yes temporary fix would be to weld the coupling on the shaft, but best to replace parts. there is meant to be a little bit of oil in the " bell" housing, but mine had none in it when I cracked it open, may be a good idea to put some in when repaired ( yours looks rusted like mine was ).