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Cat IT28G need hydraulic schematic

Discussion in 'Wheel Loaders' started by Will-Power, Jul 15, 2016.

  1. Will-Power

    Will-Power Member

    Joined:
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    Location:
    Edmonton Alberta Canada
    Hi all, I am new here, been following for a while. I have a customer that has an older Cat IT28G loader, the work functions stopped and he cant lift or tilt the bucket. The steering circuit works fine. I checked pressure going into the HRC (Hydraulic Remote Control Joystick) for the work functions and there is 300 psi going in. I didn't check the pressure coming out of the HRC for the functions. I removed the pilot pressure control valve for the HRC and it looks fine, and I also removed the relief valve for the main work function valve, and it doesn't appear to be jammed or have contamination in it.

    My guess is that the HRC is bypassing oil directly to tank and not allowing oil to go to the work functions. It would be good to have a schematic for this loader as the customer bought it at auction and has nothing of course.

    Also the hydraulic cooling fan circuit is not working, I havent looked into this yet because I would like to see the schematic first.

    Any help would be appreciated.

    Thank you,

    Will-Power
     
  2. kshansen

    kshansen Senior Member

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    Occupation:
    Retired Mechanic in Stone Quarry
    Location:
    Central New York, USA
    Will try to help with schematic, but , need at least the prefix for the machine S/N.

    Found at least two different schematics: One for WAC 1>UP and DBT 1>UP, the other says it's for 8CR 1>UP and 9AR 1-UP
     
  3. Will-Power

    Will-Power Member

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    Okay great thanks, serial number is 4TF65434. Pin is 8CR02862.
     
  4. Nige

    Nige Senior Member

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    Just a thought. You are probably going to need the electrical schematic as well, in order to see where/how the signals come from for the fan control valve.
     
  5. Will-Power

    Will-Power Member

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    Yes you are probably right Nige, so if anyone has an electrical schematic that would be helpful as well.

    Thanks.
     
  6. kshansen

    kshansen Senior Member

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    Attached should be PDF files for both the Electrical and Hydraulic schematics.

    Hope they help,

    Would have posted earlier but had a couple bikes that needed riding and some Ice Cream to get on the way, hope the delay was not a problem!

    Ken
     

    Attached Files:

  7. Mark250

    Mark250 Senior Member

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    Occupation:
    heavy equipment technician
    Location:
    victoria,Australia
    hi, did you check the hyd lock out lever. people forget what they do on these old machines
    1t28 lever lock.jpg

    there are two main things I would check
    the main relief which is at the left rear or main control valve unless it has optional 4th valve installed in which case it is in the add on valve .if this is ok I would pull the back off the main (rear) vane pump and check the cam ring and the splines on the shaft and rotor
    the splines wear out and the cam rings crack
    The fan drive is part of the brake circuit with a priority valve protecting the brakes. there are no electrical controls that can cause issues
    check the pump pressure at the test port on fan/brake pump on engine .if pressure is ok check the relief valve in the fan motor first
    Mark

    Mark
     
    Last edited: Jul 17, 2016
  8. Will-Power

    Will-Power Member

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    Thanks for the help Ken and Mark, I will let you know how it goes.

    Cheers
     
  9. walker ag

    walker ag New Member

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    May 15, 2019
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    Location:
    Indiana, USA
    Was this problem ever figured out? I'm having the same problem with one of our loaders doing the same thing, it will get all the hydraulics back if you shut off the loader and restart it, or if you move the steering wheel back and forth while trying to raise the loader.
     
  10. kshansen

    kshansen Senior Member

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    Walker, Kind of don't think he is going to respond as last time he was on the forum was Nov 6, 2016! Just another case of someone finding the forum asking for help and then disappearing. Hope the guy is okay and just had a computer meltdown and forgot how to find us again.

    Maybe jump-starting this thread will get someone's attention who can help. Not sure if there are any trouble shooting charts on SIS that would help. I'll try to look and post here if I find something.

    Well I looked and not any real trouble shooting info right off.

    I looked in the Systems Operation on Hydraulics and see this, which you may already know:
    Oil for the pilot circuits flows from the steering pump. The oil flows from the pump to a pressure reducing valve. Then the oil flows into an accumulator and on to the pilot control valves.

    So it does make some sense that working the steering can effect a "cure" of some kind. I'm going to attach the full System Op to the bottom of this message on the chance something in there give you an idea of something to check!
     

    Attached Files:

    Last edited: May 15, 2019
  11. walker ag

    walker ag New Member

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    ok thank you kshansen I'll give that a look and see what I can figure out hopefully I can get some more info to help figure out this problem.