1. Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

930G Hydraulic Problems

Discussion in 'Wheel Loaders' started by SWCP, Jan 8, 2016.

  1. SWCP

    SWCP New Member

    Joined:
    Jan 8, 2016
    Messages:
    3
    Location:
    Alberta
    I have a Cat 930G Loader and am having problems with the hydraulics. The problem started with losing hydraulics to the bucket randomly. When hydraulics were lost if you turned the Loader off and back on it would fix the problem. Eventually this quick fix stopped working and had no hydraulics at all for bucket operation. Replaced the priority valve (recommendation of local CAT dealer) and the bucket worked great for about 5 min and then nothing. During all this time the hydraulics to the steering worked. Have tried everything can think of but cannot figure it out.
     
  2. Mark250

    Mark250 Senior Member

    Joined:
    Aug 30, 2015
    Messages:
    632
    Occupation:
    heavy equipment technician
    Location:
    victoria,Australia
    Hi SWCP, serial number please TFW? TWR? the machine uses what cat calls a PPPC hydraulic system. Why did cat recommend to change priority valve did they test it?
    here are some things you should verify
    Can you feel/hear pilot lock out solenoid operate?
    do you have pilot pressure at control valve (test port on top of control right hand side of machine)?
    do you have signal pressure at pump compensator when operating a function ( left hand side of machine) ?

    Mark
     
  3. SWCP

    SWCP New Member

    Joined:
    Jan 8, 2016
    Messages:
    3
    Location:
    Alberta
    Thanks for your help Mark.

    Serial # is a TWR. We discussed the problem with CAT over the phone and they had us cheque a bunch of things and they said the problem had to be the priority valve but they did not test the priority valve.
    The pilot lock out solenoid operates.
    No Pilot pressure at control valve. Does the pilot pressure come from the brake pump?
    No signal pressure at pump compensator when operating a function except when sterling.

    When trying to move the loader we determined that if we turn the loader as far as possible to one side the hydraulics will work for the bucket.

    If you have any more suggestions it would be appreciated.
     
  4. Mark250

    Mark250 Senior Member

    Joined:
    Aug 30, 2015
    Messages:
    632
    Occupation:
    heavy equipment technician
    Location:
    victoria,Australia
    Hi SWCP, the pilot pressure comes from the main pump after the priority valve .from the priority valve pump oil goes to inlet manifold of main control valve. the pilot pressure is taken off this manifold through a small screen which can be removed and checked. (it is next to the pressure reducing valve for pilot pressure)the pilot oil then goes to the pilot oil shut off solenoid, also in the main control valve inlet manifold
    1/check pilot oil screen
    2/if screen clear remove pressure reducing valve and clean/check

    Mark
     
  5. SWCP

    SWCP New Member

    Joined:
    Jan 8, 2016
    Messages:
    3
    Location:
    Alberta
    Trying to check the screens which you suggested but I cant find them, where exactly are they? Thanks
     
  6. Mark250

    Mark250 Senior Member

    Joined:
    Aug 30, 2015
    Messages:
    632
    Occupation:
    heavy equipment technician
    Location:
    victoria,Australia
  7. Mark250

    Mark250 Senior Member

    Joined:
    Aug 30, 2015
    Messages:
    632
    Occupation:
    heavy equipment technician
    Location:
    victoria,Australia
    930G hyd sch.jpg

    Regards
    Mark
     
  8. Dumpman

    Dumpman New Member

    Joined:
    Apr 14, 2018
    Messages:
    1
    Location:
    montana
    currently having the same problem with a 938h. did cleaning the screen fix this?