Classic zetor, rear lift issue

Discussion in 'Classic Machinery' started by Greenbeast, Sep 12, 2017.

  1. Greenbeast

    Greenbeast Member

    Location:
    East Sussex
    I am damn certain i have asked this before, but cannot for the life of me find it.

    My lift arms jump a inch or so every ~5 seconds, i believe someone has told me something about a safety valve/seal letting by which causes the pump to compensate and the arms to jump.
    Getting a bit irritating and might do something about fixing it but i want to try and get the correct parts in before i dismantle anything as i'm dependant on the machine
     
  2. Gapples

    Gapples Member

    Could just be the piston seals in the lift cylinder.
    That said we used to sell Zetors & we were never done replacing the control valves.
     
  3. multi power

    multi power Member

    Location:
    pembrokeshire
    It will be an internal leakage somewhere
     
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  4. mikep

    mikep Member

    I got so pee'd off with mine doing that that i removed all the linkage control valve pack and replaced it with a single acting spool valve. £50 job done, no draft control but it never worked properly anyway. Arms now stay where you leave them all day long.
     
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  5. Greenbeast

    Greenbeast Member

    Location:
    East Sussex
    Hijacking my own thread for another hydraulics 'issue'
    It has single acting loader lift rams, when dropping, i get a sort of groaning and the engine appears to 'struggle', i'm a relative novice, what is occurring here?
    I ask in case it is not piped up correctly through the spool block, or something....
     
  6. Mursal

    Mursal Member

    The engine seems to go under load?
    Possibly because the control valve slice if that's what you're using to control the loader is letting the ram down, but expecting to put oil in the other side of the seal,double acting and its not a double acting ram. If so you need a single acting slice or do a bit of giggery pokery with the pipework, you decide.

    If its only a trip loader with only one loader pipe going to the tipping pipe on the back of the tractor forget the above.
     
    Last edited: Sep 13, 2017
  7. Greenbeast

    Greenbeast Member

    Location:
    East Sussex
    Ah yes that makes sense!
     
  8. Mursal

    Mursal Member

    Can you throw up a picture of the control valve?
     
  9. Greenbeast

    Greenbeast Member

    Location:
    East Sussex

    loader is left most slice here, so yes it has one hose connected and other port capped

    [​IMG]
     
  10. Mursal

    Mursal Member

    If you wanted you could remove the cap and using a pipe and a T, dump the pressure back into the return pipe going back to the gearbox? Or replace with a single acting slice
     
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  11. Greenbeast

    Greenbeast Member

    Location:
    East Sussex
    ok yes, like that idea, will this have any operational effect?
    Is it causing actual trouble like it is?
     
  12. mikep

    mikep Member

    Pumping against the pressure relief valve will not do it or the pump any good long term. The prv is a safety device to protect against spikes in pressure caused by events such as pumping against a closed valve but not designed as a permanent return route. Another problem will be oil overheating and premature degradation.
     
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  13. Greenbeast

    Greenbeast Member

    Location:
    East Sussex
    ok cool thankyou
     
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  14. Mursal

    Mursal Member

    If you lower the loader by just touching the level, listen for engine noise?
    You might find a spot that's fast enough with no loading of the engine. Just put a stop on the handle, save all the pipework.
     
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  15. multi power

    multi power Member

    Location:
    pembrokeshire
    There might even be a float position on the spool
     
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  16. Greenbeast

    Greenbeast Member

    Location:
    East Sussex
    How does that work and what am I looking for?
     
  17. multi power

    multi power Member

    Location:
    pembrokeshire
    It might take someone better at explain but I will try,
    So you pull lever back to lift,
    Push forward to lower (assuming double acting cylinders), then push a bit further forward for float
    Float basically all the ports are open
     
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