A well service pump system supplies high pressure working fluid to a well. The pump system includes a closed-loop hydraulic circuit for actuating a plurality of working pump assemblies. The pump system is powered by a motor, which transfers mechanical energy to a plurality of pumps, which, in turn, provide hydraulic fluid to operate hydraulic ram cylinders, and thereby operate the working pump assemblies. Each of the polished rods of the hydraulic ram cylinders is connected axially to a plunger rod end of the working fluid end cylinder to operate the working pump assembly.

Structural simplification and efficient injection state of high-pressure air from a nozzle are ensured. A foreign material removal device is provided with: a cylinder (18) into which air is caused to flow; a piston (22) which is movably supported in the cylinder and feeds the air introduced into the cylinder in a feeding direction as high-pressure air; and a nozzle (6) which injects the high-pressure air fed by the piston. Thus, the piston is moved relative to the cylinder, the high-pressure air is fed from the cylinder, and the high-pressure air is injected from the nozzle, whereby structural simplification and an efficient injection state of the high-pressure air from the nozzle can be ensured.

A high pressure fuel pump includes a pump head from which extends a turret, a bore extends along a main axis from a pumping chamber through the turret to an open end. A piston is arranged in the bore and protrudes out of the turret, an outer extremity being provided with a cam follower. A spring is arranged around the piston and slipped over the turret, the spring is compressed between the cam follower and the main part of the pump head. A cup shaped sleeve is arranged around the turret and defines a volume between the turret and the peripheral wall which fills with fuel that has leaked between the piston and the blind bore from the pumping chamber. A bottom face of the sleeve is provided with a hole through which the piston extends. An opening in the peripheral wall allows fuel to exit the volume.

A pump for reducing agents of an exhaust gas purification system for an internal combustion engine of a motor vehicle includes: a diaphragm carrier; a diaphragm arranged on the diaphragm carrier, the diaphragm having a radially outer collar; and a pump housing configured to secure the radially outer collar of the diaphragm. The radially outer collar of the diaphragm has a reinforcing ring.

A hydraulic device includes a shaft mounted in a housing rotatable about a first axis of rotation. The shaft has a flange extending perpendicularly to the first axis. A plurality of pistons is fixed to the flange. A plurality of cylindrical sleeves cooperates with the pistons to form respective compression chambers of variable volume. The cylindrical sleeves are rotatable about a second axis of rotation which intersects the first axis of rotation by an acute angle such that upon rotating the shaft the volumes of the compression chambers change. Each piston has a piston head including a circumferential wall of which the outer side is ball-shaped and the inner side surrounds a cavity. Each of the pistons is fixed to the flange by a piston pin having a piston pin head including a circumferential outer side facing the inner side of the circumferential wall of the piston head.

A linear compressor is provided that may include a shell including a suction inlet, a cylinder provided in the shell to define a compression space for a refrigerant, a piston reciprocated in an axial direction within the cylinder, a discharge valve provided at a first side of the cylinder to selectively discharge the refrigerant compressed in the compression space, at least one nozzle, through which at least a portion of the refrigerant discharged through the discharge valve flows, the at least one nozzle being disposed in the cylinder, and at least one expansion portion that extends from the at least one nozzle to an inner circumferential surface of the cylinder, the at least one expansion portion having a flow cross-section area greater than a flow cross-section area of the at least one nozzle.

A flow restrictor is adapted for application in a bearing arrangement between a piston and a cylinder of a gas compressor. The compressor includes a protective block that involves the cylinder externally, and also includes at least one inner cavity, which is fluidly fed by a discharge flow resulting from a compression movement exerted by the piston inside the cylinder. The compressor includes a bearing-arrangement clearance that separates the piston and an inner wall of the cylinder. The compressor includes at least one flow restrictor provided with a housing that associates fluidly the inner cavity to the bearing-arrangement clearance. The flow restrictor is associated to the housing by a process of at least partial plastic deformation inside the housing, the flow restrictor being provided with channels for passage of fluid, the plastic deformation being sized for limiting the gas flow through the inner cavity to the bearing-arrangement clearance.

A flow restrictor is adapted for application in a bearing arrangement between a piston and a cylinder of a gas compressor. The compressor includes a protective block that involves the cylinder externally, and also includes at least one inner cavity, which is fluidly fed by a discharge flow resulting from a compression movement exerted by the piston inside the cylinder. The compressor includes a bearing-arrangement clearance that separates the piston and an inner wall of the cylinder. The compressor includes at least one flow restrictor provided with a housing that associates fluidly the inner cavity to the bearing-arrangement clearance. The flow restrictor is associated to the housing by a process of at least partial plastic deformation inside the housing, the flow restrictor being provided with channels for passage of fluid, the plastic deformation being sized for limiting the gas flow through the inner cavity to the bearing-arrangement clearance.

A fuel pump unit includes a pump head provided with an axial blind bore within which is arranged a piston extending from an inner end, inside the bore, to an outer end, outside the head, the outer end cooperating with a cam follower and a cam of which rotations reciprocally displace the piston. The pump unit also includes a coil spring axially compressed between pump head and the cam follower and a tubular turret assembly extending toward the cam and provided with a through bore through which extends the piston, the final spirals of the spring being slipped around the outer surface of the turret. The turret is an added part, non-integral to the pump head and, arranged in abutment against an under face of the pump head, the blind bore being coaxial to the through bore arranged in the turret.

Systems and methods for operating a linear motor (e.g., for an ESP), where the motor's mover moves in a reciprocating motion within a bore of the stator. Hard stops are located at the ends of the bore. The motor has a first set of sensors in the stator positioned proximate to the bore. When the mover moves in the bore, the sensors produce corresponding output signals, except when the mover is in a position near, but not in contact with a hard stop. While the sensors produce output signals, the motor is driven in a first direction toward the hard stop. When the sensors stop producing the output signals, the mover has reached the first position, and the motor is controlled to reverse the direction of the mover.