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Marklift 62 torque hub engage

Discussion in 'Other Construction/Demolition Equipment' started by Ronray, Jul 6, 2018.

  1. Ronray

    Ronray Member

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    I recently purchased a 1980 Marklift 62 boom lift. It was delivered with the torque hubs disengaged for transport purposes. When I reversed the cover cap on the left side drive wheel, a pin sprung to the outer position and I put the cap back on with the cap button facing out. I assume that was normal. But when I removed the cap from the right side wheel, the inner pin did not slide to the outer position, as if maybe the spring device was missing or broken? Or maybe the wheel has to be rocked forward and back a little, in case there was tension on the spring device? I could easily slide the pin in and out with my fingers. The wheels still don't engage when I step on the foot pedal in the basket and move the drive lever forward and back, even though the hydraulic pump does engage when I move the hand lever. I am completely new to boom lifts. I do have the pdf service and parts manual downloaded from Genie.
     
  2. Ronray

    Ronray Member

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    Sure would appreciate some advice from someone on this :)
     
  3. willie59

    willie59 Super Moderator

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    I could be all wrong here, but I'm curious why they had the torque hubs manually disengaged (pin pushed in) for transport purposes. Typically one only disengages the hubs when the machine won't move under its own power requiring the machine to be towed to move. If it were a running machine with good drive motors/hubs, it seems one would drive the unit onto a trailer or such, not disengage the hubs. Is it possible the machine has one or more failed drive motors or hubs as reason the hubs were disengaged? I freely admit I don't know all the particulars here.
     
    mikebramel and DB2 like this.
  4. Ronray

    Ronray Member

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    Since the marklift 62 service manual states that the torque hubs should be disengaged if the unit is going to be transported on a trailer, I just assumed that's why they were disengaged. In any case, the pin on the left side sprung back into place, but the pin on the right side did not spring back to the outer position. It was just loose.
     
  5. willie59

    willie59 Super Moderator

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    Well I'll be darned, I've been working on aerial lifts since the mid 80's and I've never heard of that practice, nor have I ever seen anyone do it. Weird. I'd say you'll be going into that planetary housing to see what's amiss.
     
  6. Ronray

    Ronray Member

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    Thanks Willie! So if the Torque Hub is engaged on one side but not on the other side, do you think that the engaged side should turn by itself? Would you know of any general Publications on how to work on aerial lifts? That marklift 62 service manual is mostly a parts list. Thanks!
     
  7. willie59

    willie59 Super Moderator

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    It really depends on the machine, they're all different depending on the components fitted to the machine. For example, on some machines, like an old JLG 40F, if you were on terrain that lifted one of the drive wheels off the ground then that wheel would simply spin while the other wheel did nothing because they're plumbed parallel. On other machines the manufacturer fitted "transmission valves" to the drive circuit so that if one wheel dropped load pressure (off the ground free wheeling) the transmission valve would shift and send oil to the motor still on the ground. It may be the Marklift 62 doesn't use a transmission valve, don't know myself, haven't been around a Marklift for years.

    What you could most likely try is jack that suspect drive wheel off the ground and see if you can turn that wheel by hand, indicating something wrong inside the planetary or the motor. If it's proper you should not be able to turn that wheel. It may be easy to turn, may be stiff, but you should not be able to turn it at all if it's in proper order. If you can turn it, disconnect one of the hoses that supply drive oil to the faulty motor, use proper plugs/caps to plug the hose fitting and cap the motor fitting. Start the machine and ease into the drive, see if it now attempt to move.
     
  8. willie59

    willie59 Super Moderator

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    Aside from sources like Ebay, the only place to obtain info and parts for Marklift is through Genie Industries as Terex bought out Marklift years ago and more recently bought out Genie Industries. All Terex brand stuff goes through Genie now.
     
  9. Ronray

    Ronray Member

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    Thank you so much Willie! I will try that.
     
  10. Ronray

    Ronray Member

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    My little 2 ton bottle jack would not lift the wheel off the ground. The Marklift 62 is around 24000 pounds. So I will be picking up a much bigger bottle jack. Didn't know I was going to have to get a bunch of Big Boy tools when I got this aerial lift :)
     
  11. Ronray

    Ronray Member

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    About plugging the hose fitting, I assume that the hydraulic hose will not blow out when I engage the hydraulic pump without it being hooked up to the drive motor? And would that apply to the hose fittings to the various cylinders on the machine so that if I wanted to test the other hoses on the aerial lift I would not have to worry about blowing out the hoses when I engage the hydraulic pump well the hose is plugged or capped?
     
  12. 63 caveman

    63 caveman Well-Known Member

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    Ronray,
    You want to consider getting a mechanic to help get your machine sorted out before someone gets hurt. It takes more than "Big Boy Tools" to make a machine operate properly and safely.
     
  13. Ronray

    Ronray Member

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    Thanks caveman. I actually do have a mechanic lined up but I can't afford to have him driving back and forth 50 miles round trip from my place everyday at $95 an hour. So I am trying to get as much of the little stuff done as possible before he comes out. I would be totally screwed without the help I have received from this awesome forum. Thank you and everyone so much!
     
  14. willie59

    willie59 Super Moderator

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    Relief valves fitted to the various hydraulic circuits prevent that from happening. Same thing happens when you bottom out a cylinder or stall a motor, without relief valves you'd pop a hose or something, so circuits are protected by relief valves. All we are doing by blocking one of the hoses to the suspect motor is to prevent flow from going through that motor, we only want flow to the opposite motor. If the motors are plumbed parallel then the machine should attempt movement if the opposite motor/torque hub is good. If they're plumbed in series, which I kinda doubt, it would simply load the engine and pop open the relief valve. Again, this is after you've lifted that suspect drive wheel off the ground and have determined you can manually turn the wheel.
     
  15. Ronray

    Ronray Member

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    Thanks so much Willie for that great information! I'm going to look for the relief valves now. I assume that they would all be pretty close 2 the hydraulic pump where are all of the solenoids are lined up in a row? I have a 20 ton bottle jack due to arrive any day. My little 2 ton jack would not even lift the corner of this 12 ton aerial lift :)