A hydraulic pump distributor sealing ring for a hydraulic distributor of a hydraulic pump, includes a continuous sealing ring housed in a ring groove formed in a pump stator whose inlet-delivery ports are each aligned with a distribution opening passing right through the ring in the direction of its thickness, this ring including a circumferential-contact boss which has a circumferential line of contact that can come into contact with a rotor-side low-pressure sealing surface, the ring also including a compression-decompression track, a ring sealing lip that provides sealing between the ring and the ring groove, and rotation-proofing elements.

In a piston including a plurality of piston rings, a state where a difference in differential pressure between the piston rings is eased is maintained even after passage of time, and the life of the piston rings is extended. A piston includes a piston body in which a plurality of ring grooves is formed, and a plurality of piston rings respectively arranged in the ring grooves. In the piston, a leakage groove is formed on a low-pressure side surface of the ring groove, and in a state where the piston ring is abutted with the low-pressure side surface while being abutted with a cylinder, the leakage groove ensures communication between a high-pressure side space and a low-pressure side space with respect to the piston ring.

A piston rod assembly includes a piston rod having a first end configured to contact fluid, a packing retainer through which the piston rod extends, and one or more packing rings. The packing retainer includes one or more leakage ports forming passageways between an inner surface and an outer surface of the packing retainer. The one or more packing rings surround the piston rod, are adjacent the inner surface of the packing retainer, and are positioned between the one or more leakage ports and a bottom end of the packing retainer. The one or more leakage ports are positioned so that fluid that leaks past the one or more packing rings will flow through the one or more leakage ports.

A header and a pump end for a cryogenic pump are provided for efficient liquid pumping operation. The header directs supplied liquid into a sump and gas into a freeboard. The liquid in the header can be distributed along the header and decanted over a weir to the sump, the liquid being drawn from the sump and up through the vessel to the pump end. Gas in the freeboard is collected for venting or return to the liquid source. Pump head plunger stroke can be lengthened and operated at slower stroke rates using a large cross-sectional area intake and discharge valves. Plunger seals, supported as a seal pack in a sleeve, are field installable over the plunger. A plunger to drive shim arrangement permits filed adjustment of the stroke.

A rotary oscillating sub-assembly for positive displacement pumping of a fluid, said sub-assembly comprising: a hollow body defining a cavity having a wall with two ducts passing therethrough; a piston co-operating with said cavity to define a working chamber and including a channel that opens out longitudinally into said working chamber, said piston being movable angularly so as to put said working chamber into fluid-flow communication with one, then none, then the other of said ducts, and being movable in longitudinal translation to reciprocate so as to cause the volume of said working chamber to vary and successively suck in and then discharge said fluid, said piston carrying a sealing gasket that is formed of at least a sealing ring, a sealing half-ring, and at least one sealing strip that longitudinally connects said sealing ring to said sealing half-ring.

This document provides mechanical seals that include one or more rolling diaphragms. In one example embodiment, this document provides double rolling diaphragm seals that are usable in conjunction with various types of equipment including, but not limited to, accelerated life testing systems. In such a context, the double rolling diaphragm seals facilitate high-speed linear modulation of a variable volume pressure vessel, while maintaining precise volumetric control. Such an arrangement can facilitate an essentially frictionless linear actuation system having a long stroke, long service life, and precise volumetric control. In addition, this document provides linear actuator systems that can be used in adverse environmental conditions.

The present invention relates to a fuel pump for pumping fuel, comprising a piston (2) and a diaphragm seal element (3), which seals on an inner annular seal seat (4) and an outer annular seal seat (5), wherein the following equation is satisfied: (Ra.sup.2−ra.sup.2)/(ri+L).sup.2=ra/ri, where ri is the inner radius of the inner seal seat (4), ra is the inner radius of the outer seal seat (5), Ra is the outer diameter of the piston (2) and L is a difference between an outer radius (Ria) of the inner seal seat (4) and the inner radius (ri) of the inner seal seat (4). The invention further relates to a method for operating a fuel pump.

Disclosed is an air compressor (10) for supplying compressed air to a pneumatic system in a motor vehicle. The air compressor (10) comprises a crankcase (46), a cylinder housing (14) connected to the crankcase, a cylinder head (20), a crankshaft (40) rotatably mounted in the crankcase, a cylindrical piston (12) that is connected to the crankshaft (40) by a connecting rod (42). In order to load the compressed air with as little heat as possible, the crankcase (46), the cylinder housing (14), the cylinder head (20), and the piston (12) are made of aluminum or an aluminum alloy, and the at least one piston ring (54) or the at least one oil ring is made of gray cast iron or polytetrafluoroethylene (PTFE).

A pumping system utilizes a linear actuator to move a shaft attached to two pistons within cylinders to pump a working fluid. A housing is designed with coolant passageways and one-way valves such that movement of the shaft also pumps coolant past cooling fins and over a motor. The shaft is formed of several sections joined by couplers which slide within a bore of the housing. The couplers have a non-round shape and the bore has a complimentary non-round cross section such that rotation of the shaft is prevented.

A compressor, which includes a cylinder block and a piston assembly arranged inside the cylinder block; the piston assembly comprises a first piston, a second piston arranged inside the first piston, and a movable assembly connected to the first piston, and the movable assembly is configured to drive the first piston and the second piston to reciprocate; the cylinder block is provided with a first compression chamber that defines a space for the first piston to move up and down; the cylinder block is provided with a gas storage chamber for storing the gas after the first compression, and the gas storage chamber is connected to the first compression chamber; and the cylinder block is also provided with a second compression chamber that defines a space for the second piston to move up and down, and the second compression chamber is connected to the gas storage chamber.