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Nobody talks about lifts

Discussion in 'Forklifts/Telehandlers' started by barklee, Jan 22, 2010.

  1. Speedpup

    Speedpup Senior Member

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    thanks!
     
  2. barklee

    barklee Senior Member

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    I had a JLG man lift do the same thing. The oscilating axles stay locked when the boom was spun around or when it was elevated beyond a certain point. The sensor would stick from time to time (i think it was a prox switch) we replaced that and it never did it again.
     
  3. icestationzebra

    icestationzebra Senior Member

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    Telehandlers are the most unstable when unloaded and the boom is in the air. With the forks down you usually have about 2/3 of the vehicle weight on the rear axle. When you raise the boom you are moving its center of gravity up and to the rear, shifting even more weight off of the front axle. And a 12,000lbs machine will most likely be worse than a 6,000lbs machine because of all the extra counterweight needed (depending on outriggers). And a high boom is worse in this regards than a low boom because the boom CG starts out higher and shifts farther rearwards.

    This is the biggest trade off when ballasting a telehandler. More counterweight on the back gives you more capacity but makes is less stable with the boom up and empty - something you do every time you deposit a load on a 40ft scaffold (unless you have a Lull/Traverse). It helps to move the ballast as close to the rear axle as you can get it, as this doesn't make them as tippy when raised, but as opposed to the back of the machine it takes more mass to get the same increase in capacity.

    What you should get out of this is that it is good from a stability point of view to put ballast (ie fluid) in the tires. The mass is low to the ground and near the corners of the vehicle. Unfortunately rental houses complained so much about the extra cost to fix punctured tires that most machines don't require them anymore - but the trade off is that on average the machine weights have increased to get the same lift capacity.

    ISZ
     
  4. Speedpup

    Speedpup Senior Member

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    ISZ what tpe of steel is used in the boom construction of the lifts? Is it a high strength steel?
     
  5. icestationzebra

    icestationzebra Senior Member

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    I don't remember the specific steels that were used, but in general they use a wide mix of 40-100ksi. It depends on the particular part in question. You generally try to use the lowest strength steel you can because it is costs less and is easier to process and weld. Also, different companies tend to favor slightly different alloys because they have more experience with them and what their inhouse processes/equipment are best suited to.

    ISZ
     
  6. Speedpup

    Speedpup Senior Member

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    thanks for the answer :D:drinkup

    I noticed on the later 1044B's they added and 3/8" x 2" approx on the exterior of the first section of boom top on each side where the rollers would be below. I guess they had problems?

    Also what is happening to the steel on the boom and the rollers when extending or retracting I see tiny steel flakes in the sunlight sometimes?

    thanks john
     
  7. barklee

    barklee Senior Member

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    Ok, so i had United rentals come back out today to work on this 1155 gehl. The boom wouldnt retract when fully extended. We checked and set all pressures to factory specs and then a bit above....nothing. Then we set the pressure on the holding vavle mounted to the extend retract cylinder...nothing. By this point the mechanic thinks that the wear pads or something is binding the boom. We made a 10' long swab and lubed the inside of the boom and then we made a pump sprayer with a 12' long wand and sprayed lube on the rest of the inner booms.....nothing, actually made it chatter this time. He checked the wear pads for gap and nothing was really unusal to him. My only thought is that the boom somewhere is tweeked where it is still inside the machine where you cant see it. Strange thing is that if you bounce the boom a bit it will retract, if you set the forks on the ground (just barely) it will retract. I am stumped please any info would be excellent, i will try anything at this point!
     
  8. Speedpup

    Speedpup Senior Member

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    did you contact the Gehl factory? Can't look in the sides of the boom to see if started to bow when/if it was over loaded? Know anyone else with the same machine you could compare notes on?

    How does each section retract? one section at a time or all moving at once? Does it happen when it is 80 or 90% out?
     
    Last edited: Feb 18, 2010
  9. barklee

    barklee Senior Member

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    Yes, they are worthless. Not really enough room to see from the front and in the back they are too far foward to see. When retracted there is too much stuff in the way to clearly see if there is a bow or a dent.
    Machine works off of chains, just like a Lull. It gets stuck at the last 2 feet of the motion
     
  10. willie59

    willie59 Super Moderator

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    Hi barklee, let's try something else just to say we checked it. First, determine which hose at cylinder is the extend hose. Then, fully extend boom. You're saying at this point it won't retract, right? Once you get it in a position it won't retract, shut off the machine and remove the extend hose where it connects underneath the boom pivot. Put a cap on the line going to control valve, place the disconnected hose in a bucket. Now have someone retract the boom. When the boom is not moving while attempting to retract, there should be no oil flowing out of the hose in the bucket.
     
    Last edited: Feb 19, 2010
  11. barklee

    barklee Senior Member

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    Are you saying that if oil is coming out that is the problem? What would that be?
     
  12. willie59

    willie59 Super Moderator

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    Yes, would be a problem.

    Briefly; boom is fully extended. Telescope extend hose is disconnected, line going to control valve is capped, extend circuit hose going to cylinder is in a bucket. Now start engine and retract boom. If the boom is not moving (as has been your problem), at that moment, there should be no oil coming out of extend hose that's in the bucket. If there is oil coming out of hose (while boom is not moving during retraction) then you either have a problem with cylinder piston seal or a problem with the internal pilot holding valve cartridge.
     
  13. barklee

    barklee Senior Member

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    got it, thanks. i will try that in the morning.
     
  14. barklee

    barklee Senior Member

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    I just had a crazy idea...the holding valve on the frame tilt cylinder looks the same as the extend cylinder. What if i swaped them to see if that works???
     
  15. willie59

    willie59 Super Moderator

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    Hey, sometimes, if the cause of a problem is being elusive, just gotta try something different. Might gleen a clue as to what the problem is. I've been following your thread, it is frustrating to not be able to determine what's causing what seems to be such a simple problem. You keep going down rabbit trails that ain't got no rabbit on it. :Banghead Sometimes...just try something different. ;)
     
  16. Framer

    Framer Well-Known Member

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    I've rented a brand new one in 08 with 8 hours and had the same problem. It might be structural (aka the way it was built)
     
  17. willie59

    willie59 Super Moderator

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    Check the hose in the bucket first, just to see if oil is coming out of hose, just another tidbit of info.

    Most, but not all, cartridge valves have numbers stamped on them. See if the numbers match up. That would be great if they would switch. Before you pull the fork tilt cartridge valve, make sure the forks are tilted until pressure is off cylinder.
     
  18. Speedpup

    Speedpup Senior Member

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    Any progress on this? Just curious:)
     
  19. barklee

    barklee Senior Member

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    Funny you ask... i havent had time to follow atco's advise yet. I went out to move it out of the way yesterday and the booms go in and out now pretty well. They chatter a bit about the last 5' of extention and about 2' going in. Maybe it took a few days for the lube concoction we made (diesel and hydraulic oil) to soak into the steel of the booms. Guy from United had the side shims out of the main section of boom and i could see what looked like a dimple right behind or under the wear pads (think on both sides they looked pretty regular though) That would be on the second boom section. Dont know if thats a problem or not. Guess if the booms act up again or if im going to get it any better i might have to take a better look.
     
  20. barklee

    barklee Senior Member

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    I did talk to Gehl a while ago. They gave me the number of a dealer they like to work with for service issues. I talked to the service manager at that dealership and he said they had been selling about 10-15 of these machines per year. He said they have never had one come back for anything other than basic issues (mostly maintainence issues). So i guess thats a good sign!