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Drive motor won't spin

Discussion in 'Compact Excavators' started by OurGoldinMaples, Dec 4, 2018.

  1. OurGoldinMaples

    OurGoldinMaples Member

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    Hi guys,

    My JD 35d final drive began leaking gear oil so I tore it off the machine to dig into it. Prior to taking the travel motor off, I took the hydraulic motor side off. I fixed the leak in the travel motor and put the drive back in the machine.


    After hooking up the hydraulic lines, the drive won't spin....it just bogs the motor down. I've read a bunch online about travel motors and the parking brake. I never tore that deep into the drive and I made sure I attached the hydraulic motor to the final drive the same way I took it off.

    Drive motor is a Nachi PHV-3B-35B-PT-8906B

    Please help guys...
     
  2. Tags

    Tags Senior Member

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    Did you hook up the lines correctly? Any chance they got crossed?
     
  3. OurGoldinMaples

    OurGoldinMaples Member

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    i matched them the same as the other side.
     
  4. Tones

    Tones Senior Member

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    Hmmmm, maybe they should plumbed opposite because they run counter to each other. Hope you can pick up what I'm saying
     
  5. OurGoldinMaples

    OurGoldinMaples Member

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    So if I'm following you, one line is the high pressure line, the other is case drain. Should they be flipped on the other side of the machine?
     
  6. Theweldor

    Theweldor Well-Known Member

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    How many hoses go to the motor? A picture would be most beneficial if possible.
     
  7. John C.

    John C. Senior Member

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    I would pull the travel motor back out, hook the lines up and see if the drive shaft turned now. If not, you put something back together wrong. If it does, then you got something locked up in the final drive.
     
    Simon C likes this.
  8. OurGoldinMaples

    OurGoldinMaples Member

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    The plan is to rip it back off and see if the shaft spins. When the center shaft is out of the final drive, the rest of the drive spins by hand
     

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  9. Theweldor

    Theweldor Well-Known Member

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    Someone correct me if I am wrong.
    With only 4 hoses the 2 large ones would be forward and reverse oil to the motor. The 2 small lines that appear to be the same size, one would be case drain and one would release the brakes. Is it possible they are reversed and not releasing the brake.
     
    Vetech63 likes this.
  10. John C.

    John C. Senior Member

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    Excavator travel drive release the brakes on the inputs to make the motor turn. The top small hose is usually case drain while the lower small hose would be high speed travel.
     
  11. mg2361

    mg2361 Well-Known Member

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    Something is assembled wrong. If your hoses were backwards it would just spin backwards. The small hoses are case drain and two speed. Switching them won't keep the motor from turning. Might blow out your seal to the planetary gear box when two speed is turned on or from case drain restriction through the two speed solenoid valve, but motor should still turn.
     
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  12. Tones

    Tones Senior Member

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    All excavator track drive motors I have seen have at least 4 hoses. The 2 larger ones are the feed and return, the third is case drain and the forth is usually the 2 speed. Some have a 5th hose which is the brake. Looking at the motors if the top port on one side is for the forward direction then the bottom port on the other side is for that direction also. You need to determine that this correct.
    One other thing that I have just thought about is; does the planetary have a small button that sits in the centre of the cover so that a ball on the sun gear can run against it. If it has DON"T TRY TO MOVE THE MOTOR. That button can fall out during assembly and it will completely bugger the planetary gearbox if you do.
     
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  13. OurGoldinMaples

    OurGoldinMaples Member

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    I didn't see a small button. there are springs that surround the sun gear and a pin on the face of the motor to insure that everything is aligned correctly.
     
  14. OurGoldinMaples

    OurGoldinMaples Member

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    i can't see how it could be assembled wrong...it seems like i don't have the hydraulic pressure to release the brakes. The odd thing is, I never disassembled the drive far enough to have done anything to the brakes.
     
  15. Tones

    Tones Senior Member

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    Ourgoldinmaples, just how far into the motor did you go to fix the leak?
     
  16. Theweldor

    Theweldor Well-Known Member

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    You did say in your opening post that it bogs the motor down.
    SO it sounds as though you are getting oil to drive the motor but for some reason the brakes are not being released.
    I don't mean this the wrong way but you need to check where you have been in that drive.
     
  17. mg2361

    mg2361 Well-Known Member

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    The high pressure oil that drives the motor is what releases the brake. Did the o-ring under the brake valve housing fall out for the brake circuit? Like Tones said, there is a button behind the planetary cover and maybe that dislodged. If there is any hang up in the gear box the mechanical advantage of the planetary would be plenty to stop the motor.
     
  18. John C.

    John C. Senior Member

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    Could it be one of the tabs on the friction plate got out of place when you resembled the motor? It happened to me once with a swing motor.