The differential valve piston comprises working surfaces of at least two different diameters such that {TAIL ~ changes} in chamber pressures effect different axial forces upon {HEAD ~ the piston} 
The differential valve piston comprises working surfaces of at least two different diameters such that { TAIL ~ changes } in chamber pressures effect different axial forces upon { HEAD ~ the piston }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD