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Komatsu PC50uu-1 hydraulic problem

Discussion in 'Compact Excavators' started by apm, Oct 5, 2012.

  1. komatsugreg

    komatsugreg Member

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    Thanks - it was low - but not empty, strange that it has it's own reservoir - but now I know it's there - I can check it.
    Thanks again for your help ! The hydraulic guru is supposed to come by this afternoon, but then again, he was supposed to come by last week too :)
     
  2. apm

    apm Well-Known Member

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    the reservoir is for the gear lube. The hydraulics for the motor feed from the same system that everything else does.

    Greg
     
  3. komatsugreg

    komatsugreg Member

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    Hmm, hopefully the gear lube required is the same 30W non detergent as the rest of the machine
     
  4. apm

    apm Well-Known Member

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    that's what Komatsu's manual specifies.

    Greg
     
  5. komatsugreg

    komatsugreg Member

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    And the verdict is;
    All three functions that are weak, are run from 3 different spools,
    Right track on main spool
    Left track on 2 port spool
    Blade on 2 port spool with fast travel foot control

    All three spools are fed by separate pump sections
    So - verdict is a new reseal kit for the rotary manifold and a rebuild of the manifold
    The Hydro mech says he can do that - If I can get the reseal kit
    so that's the next challenge !

    A new day - a New surprise :)
     
  6. ruffles14

    ruffles14 Member

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    Hey guys,
    I also have the same machine (1997 pc50uu-1 with 5200 hours, bought it at 5000hrs rubber tracks). I was wondering if any of you guys can comment on the strength of your final drives? Both of mine have been replaced by aftermarket units. The left replaced by the previous owner and the right was replaced by myself a couple month ago -shaft snapped on the old. The tracks will spin no-matter-what when both are going in a straight line together. But as soon as it gets hot, i have a tough time getting either side to turn individually without stalling the final drive out.

    I have rebuilt the center swivel. both final drives are new (not remanufactures). And the relief pressures have been set at 3100psi and 3200psi for pump 3 as per manual (however when i set them the machine was not "hot"). All other functions seem to work fine. all of the track idlers are in good order. i even put in top rollers on both sides to replace the original steel rub plates.

    It has been a great machine so far, but the stalling final drives have me frustrated, especially when in tight places!

    Please tell me the weak turning ability of this machine was not innate to this model! i'm starting to think i have something faulty in my main relief valves, or spool valves? Any help is really appreciated! o_O
     
  7. komatsugreg

    komatsugreg Member

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    I your blade HYdro OK, ie: can you lift the front of the machine with it?

    As an off chance - check the spooler the road gear works off. Mine is currently stuck in high gear - and that is routing pressure differently to the drive motors. I know that when in road gear, the steering was affected - as well as the push power.
     
  8. apm

    apm Well-Known Member

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    Hi Ruffles,

    Mine is very similar to what you describe. I have also replaced a final drive and set relief pressures. Mine turns very well when the oil is cold, but gradually loses turning power as the oil warms up. I was going to look into resealing the swivel joint, but you may have saved me the effort.

    Although mine is weak when warmed up and trying to steer with one track, I can always turn well by counter rotating the tracks, even when the oil is hot. That always helps in tight spaces.

    Mine also pushes very strongly in a straight line, using both tracks. I've pretty much just gotten used to the turning and work around it. Mines got 8400 hours now and still runs like a champ.

    good luck!

    Greg
     
  9. komatsugreg

    komatsugreg Member

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    5400 hours on mine, got the seals for the swivel rebuild, the Mech will turn up one day to do it I hope as I have neither the space nor the tools. Got my drive motors serviced last year, always hod one track a little more powered than the other - just the characteristics of the machine.

    Greg
     
  10. ruffles14

    ruffles14 Member

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    komatsugreg,
    The front blade seems to work OK, it will pick the machine off the ground no problem. It does tend to gradually go up or down if i'm not paying attention, but not frequently. I think the blade wandering might have more to do with the lever linkages that i tried to tighten up and "rebush" last summer. But if it means anything sometimes my blade will lift when i swing the cab (its pretty infrequent tho??)

    when you say "spooler" do you mean the spool valve assembly for the final drives? the RH final drive operates off of a 4 spool assembly, and the LH final operates off a separate 2 spool assembly. both fed by different gear pump sections...but i think both spool valve assemblies use the same drain?

    My high speed seems to work great when both finals are engaged, it will usually bogg the engine down before quitting. but definitely will not turn a final drive individually.

    Thanks for your response!
     
  11. ruffles14

    ruffles14 Member

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    Greg,
    Thanks for the info. sounds like we have the same machine, haha!! Mine also will counter rotate better than just one final operating individually (usually anyways). glad to see your machine at 8400 hours, that means hopefully ive got at least than many hours left in mine!

    I got the center swivel joint seals aftermarket. it wasn't the easiest job to do, but i did it last winter while the machine was in its downtime in hopes that it would get the RH final drive fixed up, but it didn't do much. The original seals from the dealer were $60/pc and you need 8 of them i think...so i went aftermarket at $40 for the whole kit. In hind site i probably should've known the center swill joint wasn't bad b/c the blow by in any of the swivel "banks" would have caused another hydraulic circuit to move if it were bypassing the final drive "bank"...but it was cheap enough and i had enough freetime to redo for the peace of mind.

    i'm determined to figure this out, when i do i'll let you guys know too!

    Thanks again
     
  12. ruffles14

    ruffles14 Member

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    I got a komatsu style hydraulic tee-fitting a while back that i planned to attach my pressure meter to. Tomorrow i plan on working the machine some more, get it good and hot, then splice into the hydraulic line where it is attached to the RH final drive motor. This will at least tell me if the full 3100psi is getting to the final drive motor or if its bypassing somewhere.

    I've also heard (it may have been somewhere on here) that if the final drives don't see enough FLOW then they will essentially try to apply the brake and become difficult to spin...however i'm skeptical, b/c throttling the engine down would essentially produce a decrease in flow more so than any wear and tear would reduce it at full throttle... The valve body/main relief valves are the only thing i can think of unless gear pump FLOW is something terrible. I dont have access to a flow meter, and last i checked my cycle times are slower but aren't terrible compared to the specs indicating flow is OK.

    Hoping someone on here has solved this riddle already. Its a great machine otherwise, i just cant get the tracks to spin like i think they should!!
     
  13. ruffles14

    ruffles14 Member

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    So the full 3000psi is making it to the RH final drive when hot, and the final drive stalls out. have a call into the final drive supplier, hopefully he can provide some insight. The LH final drive is still going strong. Will let you guys know what i find out.
     
  14. apm

    apm Well-Known Member

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    They'll probably need you to do a case drain test. The procedure is pretty straightforward and spelled out in the manual.

    Greg
     
  15. ruffles14

    ruffles14 Member

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    Yes they did have me do a case drain test, very little (hardly anything) was getting by. No real answers yet. They are having me send the final drive back under warranty and will likely send a replacement out once they get back in stock and inspect it. I am letting the supplier lead the way on this, but doing some more reading on where these final drives come from -manufacturers in particular.

    Originally the pc50uu-1 came with Hy-dash final drives (obvious from they big letter on faceplate i know). That was a gmo5, which i've read was discontinued in 2004? But the aftermarket for final drives seems to be pretty vague about manufacturers and countries of origin. The aftermarket on my left side (the good side) i've been told is a "Nabtesco" unit -model# gm06vn-b-15/26-2 that says "made in Japan"...its pretty strong. Nabtesco is somehow related to hy-dash and Teijin Seiki? "Nachi" is another aftermarket supplier out of Japan that also has a good reputation, but is a competitor to nabtesco...so idk how well that brand would match my good unit. The unit i bought was pretty close on speed, but strength was no comparison. The supplier has been pretty easy to work with so far, just hoping a replacement resolves the low power...will let you guys know how it goes.
     
  16. WestsideRida

    WestsideRida Member

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    I have a similiar issue with my Komatsu PC50UU-2. I still have both Hy-Dash Drives and I have 5500 hours on my machine. Has anyone found an answer to this issue?
     
  17. komatsugreg

    komatsugreg Member

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    OK, my machine is back and running. Problem was the spooler that the road gear pedal connected to. It would not let it back into regular mode. Mech took it apart - cleaned and resealed it and all is well. Turns out I have a set of seals for the swivel joint that I no longer need !

    I want to thank all who chimed in with responses to help, much appreciated :)
     
  18. ruffles14

    ruffles14 Member

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    WestsideRida, I haven't solved the mystery yet. I just learned to live with it for now. I have pressure tested the hydraulic supply and have 3000psi to the final drives. The only thing mine can be is a flow issue with the pump (its still original with almost 5300 hours) or its a faulty final drive. I've got some projects to finish up before the snow starts falling, but when i put it away for the winter i will go through some more stuff and let you know what the problem is.

    Another forum i came across a guy that had the same issue, he said a new pump fixed him up. which he said he got from whitehouseproductsltd.com out of england. I ordered one from there at 1/4 the price of my dealer, but it didn't hold the pressure and this was before i replaced the last hydash final drive...the pump ripped the threads out of the mounting flange and all 3 sections separated losing pressure. it was only a a couple weeks old....another project this winter is to get some sort of refund and will likely try to get Parker pump model PGP511 which looks to match all the specs and still about a 1/3 the price of my dealer. I believe Parker is american made, and the specs say it can withstand 3600psi working pressure so it should hold up better.

    I also went as far as to switch the final drives from one side to the other. it seems the weakness traveled to the other side, but they both seem a little weaker now. So it might be a weak aftermarket final drive unit along with a tired pump. The place i ordered the final drive from agreed to take the final drive back to see if there was anything faulty inside. Just waiting for winter when its in storage to send it back

    I am slowly restoring this machine, so i will get to the bottom of it and i will let you guys know. Best of luck, hopefully someone solves this before me haha