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The JLG 40F Boom Lift Dilemma

Discussion in 'Other Construction/Demolition Equipment' started by od1, Sep 13, 2009.

  1. willie59

    willie59 Super Moderator

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    Yep, OFF beat me to it, looks like Cutler Hammer to me as well.

    Welcome to HEF George66. :drinkup
     
  2. maple2

    maple2 Member

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    One more post after this I can pm you Off to get that manual! Just took the big boom cylinder off and had it repacked. Not leaking any more! Not a bad job but very heavy!! Just purchased the 40f has a couple bugs to work out. It sat for almost two years. Any ideas why when the boom is extended out 1/2 way or more the boom will drift with the wind in neutral position. If its retracted below 1/2 it holds tight? The fluid is not low its right in the middle of the add mark and full. Thanks for any help on this!
     
  3. maple2

    maple2 Member

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    Just more info on the above post when it drifts it will drift left to right or right to left. It does not drift down.
     
  4. OFF

    OFF Senior Member

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    But it will still swing when you ask it to swing? We are talking boom swing and not basket rotate, right? When you grab the basket, can you push the whole boom sideways?

    Swing (boom) has a brake section on it between the swing motor and the swing gear box. Sounds like your swing brake is not braking. It's spring applied, hydraulically released. That's where you need to look first.
    It's a pretty simple assembly, just a piston, some clutch discs and plates and bunch of springs.
     
  5. maple2

    maple2 Member

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    Yes its the swing boom. When the boom is extended beyond the half way mark you can grab the basket and push the whole boom. Do you have to take the swing motor off to get to this brake? Besides this issue the basket rotate is not working, I am hoping its just the switch, I haven't checked it yet. These are the two major problems left with the old lift! It goes very good on hard level ground it does not like soft or non level surface!
     
  6. OFF

    OFF Senior Member

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    Ok, your swing brake isn't broken it's just weak or out of adjustment. Have a look at your swing motor, is there a cover on top of it? Is there an external brake disc and 2 pads on a caliper under that cover? There were 2 types of swing brakes used on the 40F, let's determine which one you have.

    As for the operation on soft and uneven ground......it's a rigid chassis and that's just the nature of the beast. You can get yourself out of some spots by swinging around so the counter weight is over the drive wheels rather than over the steering wheels. Aside from that, there's not much you can do. They are not off-road machines
     
  7. maple2

    maple2 Member

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    IMG_0677.jpg
    Thank you OFF for the manuals. I have a feeling I will be looking at them everyday for a while! I think I found the problem with the swing brake. I saw a small drip of fluid coming from the cover. Took the cover off and brake is covered in hydraulic fluid. It has a leak! I could not pin point where leak is coming from it was getting dark. I will look in the morning. Hopefully easy fix?! Maybe Hose to piston or piston. Not sure what else it could be. But the oil on brake I am sure is making it slip.
     
  8. OFF

    OFF Senior Member

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    You have an external disc swing maple2. Adjustment is very critical on those as the "spring" that applies the brake pads is a stack of wavey washers and there is not a lot of travel to play with. That cylinder is pretty basic inside, 1 seal I believe, a piston and a stack of wavey washers.
     
  9. maple2

    maple2 Member

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    Yes it's the piston leaking. I have the piston off now. Hopefully once we take it apart it will be a standard size o-ring or seal I can buy local.
     
  10. willie59

    willie59 Super Moderator

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    I haven't taken one of those cylinders apart in ages. But like OFF stated, there's a stack of Beleville washers behind that cap on the cylinder putting the whole thing under spring tension. I just can't recall if it comes unglued when you screw that cap out.
     
  11. maple2

    maple2 Member

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    Took that cylinder apart nothing is ever a quick fix! Found a lot of broken beleville washers inside. The very top of piston housing is scored from this. Although I think it's still usable because its high up the piston won't touch it as it moves. The problem is where to find the new washers and how many to use since the broken ones are so ground up. Tried to get the washers locally the ones I found were twice as thick as the original ones. Not sure if they would work because of thickness. I could not find any part number for the washers to order them direct.
     
  12. willie59

    willie59 Super Moderator

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  13. dbris

    dbris Active Member

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    On the subject of the swing brake, is there a way to release it so that the boom can be turned by hand? We have an intermittent problem with the proportional valve for the swing motor and sometimes it refuses to swing to the right. It goes left no mater which way you push the control. Today one of the guys got it jammed in a narrow yard and now I think that I'm going to have to release the brake so I can turn it. What a mess! Any ideas? Model is 40F, about 1978.
     
  14. Jonesy

    Jonesy Member

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    My JLG rebuild is moving along, but very slowly. I've diagrammed all of the wiring I can, and have pulled all wiring & controls out of the basket. I've started diagramming and pulling the hydraulic hoses. All of the wiring and all of the hoses are in ruins. I have no idea how it unloaded itself from the trailer. I've also removed the gas tank, and am working on removing the hydraulic oil tank. There is about 6" of sludge under both tanks and in the center cavity (the machine came out of a stone quarry/concrete plant.) I've decided to strip the unit completely down. I figure it will take me at least a year to complete. Some of the stuff, like rebuilding the basket, I can do in the shop over the winter. I'll also have all of the hydraulic lines duplicated over the winter.
    Is it possible that one of you guys could shoot me a manual? I'm thinking that would be a great advantage, especially since I'm pretty sure the guys who owned this machine previously did some questionable "hurry-up" fixes.
    I did have a good time rebuilding the bent-up cable tray. I think it will work -- we'll see. I removed all remaining steel horizontal cross rods, and replaced them with 10-32 all thread covered with steel brake line. It seems pretty strong, and looks good too. Sounds kind of hokey, I know, but we'll see how it works; As long as it protects my new electric cables and hoses, I'll be happy.
     
  15. Jonesy

    Jonesy Member

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    My rebuilt cable tray. 100_0608.jpg I'm committed now. This is what $1000 of wire looks like. 100_0609.jpg
     
  16. Jonesy

    Jonesy Member

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    George....I have the same set-up with the joy sticks and micro switches. It appears that our machines are very similar (except yours seems to be in much better overall condition). I see yours even comes with a tow bar...nice. The spring seems like an easy fix (I'm looking for new ones myself), but a simple fix for the joy sticks might be to add weld to the worn areas and then grind them down or turn them on a lathe, to the dimension you need. (Just a thought.)
     
    Last edited: Sep 28, 2014
  17. OFF

    OFF Senior Member

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    Jonesy, I sent the manuals again. This time I broke them down into smaller files in case they were blocked due to their size when I sent them on April 25.14.
    Let me know if they don't come through.
     
  18. maple2

    maple2 Member

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    Put the new wavy washers in the piston for the swing break and it works!! Have a drip comming from the piston still I did not change the two seals in piston. I will order them Monday. Would like to thank OFf and Willie59 for there help.
     
  19. Grovecomm

    Grovecomm Active Member

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    Can anyone tell me the proper engine RPM on a 40F? There is a solenoid attached to my carb linkage, is that to pull the throttle on or off? I still don't have mine running. Any thoughts on a replacement engine I should look at?
     
  20. Grovecomm

    Grovecomm Active Member

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    The 12 volt motor on my emergency hydraulic pump appears to be shot. Has anyone replaced one or had it rebuilt?