[jdkskyking]

I agree Richard. 

Regarding the self centering of the ZF RAS system.

ZF has specific values for the pressure accumulator nitrogen charge and for the “hydraulic” side of the closed loop system. ZF provides the pressures in “bar”.

I personally believe the ZF recommendation for the pressures are to provide proper operation AND allow the driver to “overcome” the ZF RAS centering system in the event of a hydraulic system malfunction. 

If memory serves:
ZF RAS Pressure Accumulator:
Nitrogen charge 10 bar (145 psi)
Hydraulic charge 15 bar (218 psi) 

I know for a fact that the RAS system functions perfectly at these values and I was able to overcome the centering system with the engine in off, steers and tags on pads to allow the system to function. 

The key to success with the ZF RAS system is bleeding the air before setting the pressures. 

Don’t forget, pressure accumulator “pressure” should be checked annually and the bottle replaced after being in service 10 years. 

JK