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.
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
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.
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
Trying to check the screens which you suggested but I cant find them, where exactly are they? Thanks
Regards Mark
currently having the same problem with a 938h. did cleaning the screen fix this?