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Hydraulic pump question

dannyaussie · 2022-02-01 04:46

I’ve got a 5 ton kubota excavator, It has a KYB variable displacement piston pump and the problem I’m having is that 1 output is noticable weaker than the other. When I swap the outputs at the control valve I find that it’s the output of the pump that is causing my weak functions. it had the pump shaft replaced last year and it was disassembled and reassembled by a machinist. Is there any adjustment that can be made by me to the prv or should I send it to an specialist to get it bench tested? Thanks!

Replies8
  1. #1uffex2022-02-01 08:00

    Good day Danny Which 5 ton Kubota are we talking ? Kind regards Uffex

  2. #2dannyaussie2022-02-01 08:06

    Hi Uffex It's a kubota kx161-2 the pump is a kYB psvk2-25ckg it has 2 main outputs and an output for the pilot circuit. When I swap the outputs around the weak track becomes stron and the strong weak which i assume indicates that one output of pump isn't functioning correctly.

  3. #3uffex2022-02-01 11:57

    Hi Danny I agree with your diagnostics, I will search the archives for that pump and possible cause. KR Uffex

  4. #4uffex2022-02-01 12:03

    PostScript Danny this is a standard machine, no third party extra's installed to the pump lines?

  5. #5uffex2022-02-01 12:35

    Good day Danny According to our information, your machine pumps shares a regulator, this would indicate that there is an actual defect with one of the pumps. It would be of interest as to what caused the original failure, if you have a flow meter - pressure tester you could test both units and compare results or if you have a pump specialist nearby, that may well be the best bet. Removing the pump from that machine is not so difficult. Kind regards Uffex

  6. #6dannyaussie2022-02-01 16:06

    Thanks for the information Uffex, when I had it apart last year the splines on the shaft were worn. A machinist disassembled and reassembled it. Something must have gone amiss. I'll remove the pump and take it to a specialist to repair. Thanks again

  7. #7uffex2022-02-02 04:03

    Good day Danny I suggest if you can get a look when its apart pay particular attention to the pistons - barrels -& lens plate. Kind regards Uffex

  8. #8dannyaussie2022-02-10 03:57

    Took the pump to a hydraulic pump specialist and he found the issue/s. Unfortunately the machinist who previously had the pump apart skimmed the valve plate thinking he was improving its condition instead it has meant the cylinder block, pistons and valve plates must all be replaced. Glad to have gotten to the bottom of a hydraulic issue that has made operation difficult, thanks for the help Uffex