A piston system for a reciprocating compressor is adapted for high speed, high
pressure unloading conditions by providing a dual stage piston assembly wherein
the piston is adapted for absorbing and redistributing a portion of the load during
the high pressure applications or high pressure portion of a cycle without reducing
the efficiency of the system during normal loads. Pressure of up to 4000 psi can
be handled without damage to the piston or other valve components. The valve plate
is held in the closed position by a compression spring which is adapted to be engaged
by a finger/driver upon reciprocation of the valve piston. The finger driver moves
with the piston against the valve plate to open the valve on the plunger downstroke
and move away from the valve on the plunger upstroke. A shock absorbing element
is positioned in the plunger/finger assembly to absorb the shock of the driving
downstroke, thereby reducing the shock of the finger against the valve plate.