Pump valve structure

793,057. Piston packing. FOOD MACHINERY & CHEMICAL CORPORATION. June 28, 1955 [Oct. 13, 1954], No. 18607/55. Class 122 (1). [Also in Group XXVIII] A pump piston 35 comprises a packing washer 103 of yieldable material surrounding an extension of the piston-rod 30 and sealingly engaged on its upper surface by a member 105. The packing washer is clamped, by a set-screw 110, between a backing washer 108 and the member 105 which has a circular projection 104 pressed into the upper surface of the packing washer. An 0-ring 106 seated in a recess in the washer 108 is compressed into sealing contact with the rod. To prevent it from entering the pump crankcase, liquid leakage past the piston is deflected by a hood 115 that is held between the washer 108 and a shoulder 118 on the piston-rod and surrounds the rod and the crosshead guide.