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The JLG 40F Boom Lift Dilemma

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

  1. OFF

    OFF Senior Member

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    Not sure I have any left, but I'll look tomorrow and let you know.
     
  2. OFF

    OFF Senior Member

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  3. Gus71

    Gus71 New Member

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    Thanks for the help. I didn't have the number when I had searched for them in the past.
     
  4. Asa Tower

    Asa Tower Member

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    Wayland ny
    Need help please!! Jlg 40f
    Back story- drive, up down and rotate was bogging motor down so pulled filter out by Bertea valve, cleaned put back in. o some lines looking for small inline screen filters with no luck. Fired it back up and now have no bertea valve operations.
    Tried bleeding some lines close to the valve, played with the flow divider a bit, let it run for quit a while. Found that if I had high idle and high speed on I could get all my movements but only if I’m driving forward and back.
     
  5. OFF

    OFF Senior Member

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    Hello Asa Tower, I saw very few Bertea valved 40F's back in the day, so I never became good at them or even figured out how they worked. I've attached a Bertea valve manual. Hope it helps.
     

    Attached Files:

  6. OFF

    OFF Senior Member

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    I didn't realize until now I could attach files directly to a post. That one above is a little large, Mods, let me know if I've done a bad thing please.
    Here's the Bertea basket wiring schematic. Check out those 2 diodes, they appear to be in play in this situation.
     

    Attached Files:

  7. Asa Tower

    Asa Tower Member

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    Thanks for the reply I ended up finding the problem, it was the dump valve causing all the problems. Took apart and cleaned, good as new! Just did head and manifold gaskets as well very smooth machine
     
  8. ChuckSD

    ChuckSD New Member

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    Hello Everyone, This is a awesome thread! I have been reading through and have learned a bunch!
    I'm new here and hope I can make some connections and get some help?
    I have a 40H that wouldn't drive. read all through the manual and talked to local guy who told me to clean the spindles the coils go over on the racine proportioning valve.
    This unit has been setting a couple of years with very little use! I cleaned everything up and then tested the functions by pushing in on the little center pin. They all seemed to work better until I pushed the one for forward drive, it went in very hard [almost a pop!] and now nothing works except when i go to the basket and put my foot in the Deadman switch the lift takes off in forward!
    I'm assuming the valve for the forward motion is stuck. My problem is how to get it to pop back out? Do I have any options without taking that valve apart and if I do, it looks like there are a million parts that could potentially fall out!
    Any advice for a Newbie?
     
  9. OFF

    OFF Senior Member

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    Hi Chuck, You've got Racine proportional valves? Later model "H" series went to Vickers.
    What happens when you push the other small button for the other direction of drive? Will it push? Does it have any effect?

    At the bottom of the valve section, there is a set screw with a 1/2" lock nut on it. This set screw adjusts the centering of the valve. Sounds like your valve went full stroke one way and got stuck. You may be able to bring it back by adjusting it the other way. Screw the center set screw in about 3 full turns, try the drive. Then if that does nothing, screw it out about 6 full turns and try it again.

    If that doesn't work at all, you'll be taking the valve apart.
     
  10. John Rapoza

    John Rapoza Member

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    Hi Folks,
    I have just purchased a JLG 40G (date looks like 82) that has been sitting outside for a long time (about 7yrs) without the engine cover on, View attachment 202607 in the Vermont weather. The engine runs good until it is under load, then slows to about idle or less, moving it was a challenge :) I noticed the oil has water mixed in, I will change that tomorrow evening with any luck. it seems to have lots of electrical issues, (responds when it wants to) I believe I have seen every function work at least once, (with the exception of the AUX pump), but they are all very sporadic at best.
    Overall the machine looks to still be solid, I would love any and all advice on these issues, and if anyone would be willing to sharing any manuals for this, I would very much appreciate them.
    I'm really looking forward, to putting her back into good shape.

    Thank you all, this is the best place I have found for information on these machines.
     

    Attached Files:

    Last edited: Oct 2, 2019
  11. OFF

    OFF Senior Member

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    Hi John, welcome to HEF.
    I don't have a manual set for the 40G unfortunately, but they were made up from parts somewhere between a 40F and a 40H of course. The 40F manuals I can email to you. I believe the 40H manuals are downloadable from the JLG website. I looked after two 40G's back in the early 80's, they were brand new machines at the time. I remember the sliding hoods being a real pain, even when new. Probably why yours was left without a hood on it for so long. Yours has a V-4 Wisconsin gas engine. I think most of them did.
    Those engines absorbed rainwater, so I think your first project should be to drop that oil and filter and start fresh. A tank of fresh gas and set of spark plugs might fix it right up. When it falls on it's face under load, to me that's bad plugs/bad gas. Replace the oil in that "oil-bath" air cleaner too.
    The fact that you've witnessed every function work at least once is very encouraging. I think I might start by opening up the basket and ground panels and spraying everything with some sort of water drying/displacing spray. Look at all the exposed wiring, like on the valve body for rusted or loose connections. There are several ground wire connections on the valve of each function that like to rott off.

    Always - start with the simple stuff first.
     
    Last edited: Oct 3, 2019
  12. John Rapoza

    John Rapoza Member

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    Will do, Thank you!
    I hope to have an update after the weekend
     
  13. OFF

    OFF Senior Member

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    Drain the float bowl on the carburetor too if you haven't already.
     
  14. John Rapoza

    John Rapoza Member

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    Flushed the oil twice, then filled with 30W rotilla, this made a big difference, but now I cant engage drive to test it.........
    Pulled the entire control panel apart, sand blasted and painted the housing, nex ti will clean or remake every connection so I will know they are good.
    Also testing the components as best as I can in the QR controllers.
    There was a capacitor laying in the bottom of the control box, very corroded. I have tried to research as best I can for its specs. not finding much...
    I tested it, and it is totally dead. I have found a different machine with a capacitor in the same location, but not sure if it actually is the same.
    Does anyone know about this capacitor, value and or function? It may be a 1000uf 25V if it is the same as the other JLG model.
     
  15. OFF

    OFF Senior Member

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    I'm looking at a 40F PQ controller/Racine valve drawing, and it shows a 100uf 25V capacitor. JLG part #1540002. The drawing shows it going from terminal #35 to terminal #25. #25 is grounded, which makes sense. but What it actually does in the circuit? It's in series with a diode that runs to terminal #36, and that's listed as ignition power. Might be something to do with stopping the engine from continuing to run after the ignition is shut off. It is involved with power supply to the controllers however.

    The diodes they used are JLG #3990001, spec'd as 3.5 amp 1000 volt and #3990010, spec'd as 6 amp 1000 volt. I'd go with 6 amp if you need to replace any. That's what most of them are anyway.
     
  16. OFF

    OFF Senior Member

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    On the ground control drawing, it shows another capacitor. This one is 1000uf 25V and uses the same part number as the basket control one they spec'd out at 100uf. Maybe that 100uf I saw was a misprint. Go with 1000uf. That's all I've ever known them to use.
     
    Last edited: Oct 8, 2019
  17. John Rapoza

    John Rapoza Member

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    Will do, thank you :)
     
  18. John Rapoza

    John Rapoza Member

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    I think I am making headway...
    New Gaped Plugs, Adjusted valve lash, replaced Carburetor, messed with throttle, and governor adjustments. Checked mechanical advance, to be sure it wasn't frozen, very little change...
    tweeked the timing counter clockwise, made it a little worse, tweeked the timing clockwise, a little better, five more tweeks, the engine is really starting to sound about right. I used the machine yesterday to do repairs to my roof, tweeked it one more time when it stalled trying to swing the basket. I was actually able to use it, and move it almost like it was meant to be used, big sigh of relief! I still have a few more things to fix on it, but it is looking positive :)
    Thank you OFF for your advise and support. I really appreciate your assistance, and this forum for being here, and giving lots of ideas and advice.
     
    OFF likes this.
  19. JLG Newbie

    JLG Newbie New Member

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    Location:
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    I need help finding parts to rebuild my JLG 45 master cylinder. The machine looks like all these pictures of 40F's but I think it's a 45 something. Early model for sure. I removed the piston from the master cylinder and it had aluminum insides with seals. Anybody have any documentation I can compare to what I have?
     
  20. Kbitt105

    Kbitt105 New Member

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    SW, Pennsylvania
    I have a 40 f. Recently it has started slowly bleeding down on the lift cylinder. The cylinder was rebuilt not long ago maybe 100 hours. Worked flawlessly until now.I can't figure out what exactly is the holding valve in the system? Can anybody help me? Any other suggestions as to where to look for the bleed would be greatly appreciated.