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Cat TH514 - Hydraulic Problem

Discussion in 'Forklifts/Telehandlers' started by rudy116, Dec 9, 2016.

  1. rudy116

    rudy116 Member

    Joined:
    Dec 9, 2016
    Messages:
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    Location:
    Miami, FL.
    Hello everyone! New to the forum.

    I have an issue that has me really confused. Hoping someone can help me out. We have a TH514 that broke one of the pins holding the left cylinder on the rear of the machine that I thought was a lift cylinder...apparently CAT calls them tilt compensation cylinders.

    At first we thought that someone had hit the machine and broke the cylinder off but after a closer look, it seems like the cylinder was not working properly and broke itself off. When we pull the joystick back to lift the boom, the cylinder does not move together with its partner on the other side of the boom. It only moves when we hit the button to tilt the forks. Doesn't seem right to me!

    So I thought maybe a bad solenoid. Looked in the back at the control valves and realized that the fork tilt cylinder and two back "compensation" cylinders are all plumbed together. Now I'm stumped! What the hell do those "compensation" cylinders do, and why would it function that way???

    Also, we bought the machine used and I always noticed that when I lift or lower the boom, the engine bogs down. When combined with tilting the forks, it bogs down really bad and has even shut off. I thought it was strange because my older TH360 doesn't have this problem at all. Now I'm thinking that all of this could be related.

    I don't want to reconnect the cylinder and have it break again. Any help is greatly appreciated!
     
  2. Delmer

    Delmer Senior Member

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    WI
    Just a guess based on some googll images:

    Those cylinders keep the forks at the same angle to the frame as the boom is lifted and lowered. They are a "master cylinder" or motor, that forces the fork cylinders to move proportionally as the boom goes up or down.

    Your second full paragraph isn't a concern, the boom moves the cylinder. Seems right to me.

    Can't tell you if there's something wrong with your engine, hydraulic pump, controls, etc. I would try to get to the bottom of it before fixing the cylinder. Have you changed the oil? sent in an oil sample? engine and hydraulics. Does it seem to have expected engine power?
     
  3. rudy116

    rudy116 Member

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    Location:
    Miami, FL.
    Thanks for the explanation! Makes sense...Now I understand how it works. We changed all filters and engine oil when we bought the machine but did not send in the sample. Did not change hydro fluid but maintain level. It definitely has full power, not throwing any codes, and was hooked up to a computer. Nothing was found.
     
  4. rudy116

    rudy116 Member

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    Location:
    Miami, FL.
    Just thought of something...Could the drop off in power be that the cylinder was bad and causing excessive resistance? Since the cylinder is actually moved by the boom, I'm thinking that the cylinder must have frozen or something in order for it to break the pin like it did. The pin is at least 1-1/2" thick.
     
  5. Delmer

    Delmer Senior Member

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    If the cylinder was THAT bad it would be sending metal chunks downstream in the oil. Any chance you have the old hydraulic filter, or took it apart to look for metal flakes?

    I agree, something is seriously wrong to break a pin like that. Possibly it was seriously overloaded previously, and a bunch of things are bent/cracked? or the hydraulic pump is disintigrating, and/or the cylinders are messed up.

    Can you post a picture of the broken pin? a shot from the ends showing the break pattern, and one of the length of both pieces with a straight edge on top would be interesting.

    edit: if you were in Missouri, for instance, I might suspect the cylinder had enough water to FREEZE, but not in Miami, right. How does the hydraulic oil look, nice and clear, or milky?
     
    Last edited: Dec 10, 2016
  6. rudy116

    rudy116 Member

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    Location:
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    There was no metal in the filter when the oil was changed. I need to recheck it now and see what the fluid looks like too. Interestingly, I did have to add almost five gallons of fluid the other day but it has not gone down at all since then and it has no leaks that I can see.

    I already threw the pin away but here are some pics. You can see where the pin broke right in the middle where the bolt goes through and the cylinder eye is bent too. If look close at the other pic, you can see that the hole is slightly ovaled towards 1 o'clock. That tells me that the cylinder was either stuck extended or tried to raise the boom and that's why it broke. The question is why? I have a new cylinder to put in, but now I'm worried about breaking it again until I figure out why it happened. :Banghead:Banghead:Banghead
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    Attached Files:

  7. Delmer

    Delmer Senior Member

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    On that third pic, is that rust or grease running down from the main boom pivot joint? If the fork tilt joint is as rusty as that looks, and it was even moderately overloaded regularly, then that would explain it for me. When the boom goes down, that cylinder has to force the forks to tilt up, if everything is straight and greased it should be plenty strong enough, but with that pin only "single shear" I can see it breaking at that bolt hole if things are tight, bent, and rusty at the other end of the boom.
     
  8. rudy116

    rudy116 Member

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    Location:
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    Gotta double check, but I think it's rust. I'm gonna grease everything up real good and check everything. From now on, I will have to take time to maintain our equipment better. Obviously, I can't rely on my guys to do it.
     
  9. Clguest

    Clguest Well-Known Member

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    USA
    A thought - if the hydraulic flow from this slave cylinder to the tilt cylinders near the forks is blocked then either the hydraulic fluid pressure must be relieved or would blow a line or cause a mechanical failure I would think. Possible causes - miss plumbed, stuck relief valve, stuck control valve?
     
  10. rudy116

    rudy116 Member

    Joined:
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    Location:
    Miami, FL.
    So here I am 4 years later and we broke the same pin again. I'm thinking there has to be something wrong with the hydraulics. The machine has given me problems since I bought it. When you lower the boom, it wants to stall out. Mechanic says he changed the relief valve on the tilt/comp circuit. Now the stalling is worse. You can't make two motions at once and the hydraulics are dead slow. If anyone has any suggestions that would help me avoid the dealer, I would appreciate it.