Vac pump gearbox cog removal

Discussion in 'Machinery' started by flatliner, Feb 11, 2019.

  1. flatliner

    flatliner Member

    Location:
    East Tyrone
    I've got a mec - 86 H vac pump on which the small cog in the gearbox has several broken teeth what's the handiest way to remove the cog?

    Cheers
     

    Attached Files:

  2. john432

    john432 Member

    Location:
    Carmarthenshire
    Take the outside nut off, but the rotor will rotate ! So you need to jam the cog with a piece of angle iron, anything suitable against the inside of the housing. Then the cog is held on by the keyway in the rotor shaft, think space is limited for a puller set,so try a chisel or pry bar up behind it. If that fails weld the cog to a piece of pipe, with something welded to form a T ,then just get the big hammer out!
     
    flatliner likes this.
  3. james ds

    james ds Member

    Location:
    leinster
    The broken teeth aren't your only problem , are the finns broken and wedged in the rotor . Something went wrong to cause the teeth to go.
     
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  4. john432

    john432 Member

    Location:
    Carmarthenshire
    Too aggressive start ups??
     
    flatliner likes this.
  5. davidroberts30

    Location:
    pembrokeshire
    cut the cog off,its fooked anyway
     
    flatliner likes this.
  6. I have just rebuilt my jurrop vac pump (seals had gone either end) couldnt get the small cog off, it was locked solid on to the taperd shaft, had to cut it off. Not sure if the mec pump is the same.
    I would certanly recomend going right through the pump, and fit new vanes anyway as your at it.
     
    Last edited: Feb 11, 2019
  7. Mursal

    Mursal Member

    Lock the shaft, but don't break the housing.
    Impact gum might take the nut better than a socket and bar, then hopefully the gears loose.
    A bit of heat or as above nick the gear with the gas.
     
    flatliner likes this.
  8. mengeleguru

    mengeleguru Member

    Location:
    Derbyshire
    When you have stripped it down check if the rotor isn't bent as the shafts dont go right through . .
    If it is may as well buy a new pump .
     
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  9. flatliner

    flatliner Member

    Location:
    East Tyrone
    John432 has got it in one. Soft start had quit working on the tractor, rotor turning freely by hand so I think the vanes are ok. Cheers for the tips, i'll give it a go tomorrow .
     
    john432 likes this.
  10. 335d

    335d Member

    Once you get the nut off, take the complete gearbox housing off the rotor housing, complete with rotor. The local expert has a large piece of pipe, sitting vertically that the rotor can drop into, long enough that the rotor won’t touch the ground.
    Drop the rotor into the pipe vertically, being careful not to nip fingers. Then lift the complete rotor assembly 6 inches and drop, keeping hands clear. The weight of the rotor falling should break the taper and the rotor will drop out. The experts make it look sensible.
    If you don’t have a piece of pipe large enough, you could knock a little stand up with a few pieces of scrap iron, or a few concrete blocks.
     
    fiat 9090 likes this.
  11. Stock

    Stock Member

    My method would be to dismantle the front of the pump pull pot the rotor remove the vanes then open the nut and cut the gear off replace the bearing new gear and seal, wash the vanes check for damage replace if necessary then reassemble.........................................
     
    flatliner likes this.
  12. Do they spec. a certain amount of runout on the rotor?

    On screw comp. rotors the tolerance is very small and it doesn't take much at all to ruin an air end.

    It would be a shame for the OP to spend only to find the pump was utterly stuffed as the rotor was warped.
     
  13. flatliner

    flatliner Member

    Location:
    East Tyrone

    Worked a treat! (y)
     
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  14. The heat from welding probably helped too. Nicely done.
     
    flatliner likes this.

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