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Sundstrand Pressure Checking - Recovered Article

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This is a recovered article by @BLT


By BLT (edited)

  • February 15

June 24, 2014

@Brettw and myself spent some time looking and calling for some information to help with his power steering question. So we we tidied all up in on area.
It is assumed that you are equipped with the hydraulic lift and equipped with this relief valve arrangement:



"A" 1/8 NPT Allen Hd pipe plug. This testing port is for the charge pump, and should show an operating range of approx 50 PSI at idle, to 180 PSI at wide open throttle.

"B" 1/8 NPT Allen Hd pipe plug.  This testing port is where implement pressure can be measured @ 630-780 PSI) WOT with full extension of the implement.

"C" Charge relief valve. Where you add or remove shims to get the desired pressure per above (A).

"D" Implement Relief Valve. Where you add or remove shims to get the desired pressure per above (B).

"E" Implement supply port. Pressurized fluid out .

"F" Implement return port. Return fluid.

"G" Test gauge 0 - 1000 psi and hose ass'y, with snubber or dampening valve and brass fitting to transition to 1/8" NPT.
The snubber is used to dampen gauge flucuation that is common in hydraulics. Now when testing Brett's machine there was no gauge "bouncing".

Pressures are adjusted with shims in the charge relief valves shown. Adding shims increases pressure, removal lowers pressure.
These shims vary in thickness from 1/32" or less to nearly 1/16". Very small differences can create very different pressures.
Pressure on the supply port is measured when the implement is at its extents and held in place (fully raised or lowered and held there, or full left or right on the steering and held there), at wide open throttle.
All adjustments or testing must be done in a clean environment.
Make sure all ports or valves and surrounding areas are free of any and all dirt, dust or other contaminants before removal or replacement.

The Sundstrand 15 is capable of a maximum operating pressure of 3000 PSI, therefore all due caution, PPE, etc. should be observed when performing any adjusting or testing, as personal injury and / or damage to equipment could occur if excess pressures are created.


Edited February 15 by BLT

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