{HEAD ~ load pressure transducer} means for measuring {TAIL ~ the pressure} in the supply line between the restrictor and the pressure sensor and providing an output signal indicative thereof which is supplied to the control means; and 
for measuring
{ HEAD ~ load pressure transducer } means for measuring { TAIL ~ the pressure } in the supply line between the restrictor and the pressure sensor and providing an output signal indicative thereof which is supplied to the control means ; and
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH