Sundstrand Hydraulic Series 15 U Style Unit
When you are not using the implement relief valve, use the charge relief valve. The charge relief that was in use is not plugged up.
The charge relief valve when repairing, take out the plug, then put in the spring and poppet out of the housing. Try not to mess with the shims or try to make other parts work in valve. Look over the poppet and where it sits in the housing for any kind of wear and tear or mark, scuffs and take out any debris in the valve space. If you need to replace worn out parts do so and clean out the space before putting in new parts.
When putting in the implement relief valve (which up to you) take the plug out and put in the spring and poppet out of the housing. Again don’t mess with the shims or try to put parts from something else in the valve space. Look it over, clean out the valve space and put in new parts if it needs it.
Same thing with the acceleration valve too, don’t put part from something else in there, clean it out and put new parts in if they are needed.
It is that way for any part you take off and put in a new part. The debris that is left will go thru the pump and lines and mess up your pump and machine.
If you need more info on this unit call us at 800-361-0068