A control device for controlling a displacement pump or motor, comprising a variable mechanical device, comprising at least two masks, wherein the at least two masks are phased relative to each other and a shaft, and are configured to create a desired cam profile. A cam follower is operatively connected to at least one of an intake valve an output valve of a displacement pump or motor.

A fuel pump includes a holed disk-shaped plate and a coil spring to press the plate toward a lifter. The plate has an inner circumferential surface to be engaged with a groove in a projection-side end portion of a plunger. Also, a joint port that connects the inner peripheral surface of the plate to an outer peripheral surface thereof is provided in the plate. The coil spring is located between the plate and a pump body. The plate is assembled in the fuel pump to dispose the joint port at a position in an opposite direction to the direction of a side force to be generated during compression of the coil spring when viewed from a central axis of the coil spring.

A self-energizing valve includes a valve body defining an inner chamber having an inlet and an outlet. A valve head within the inner chamber is moveable between a first position and a second position. A valve seal in fluid communication with the inlet has a sealing surface with a sealing member between the valve head and the valve seal. The sealing member is movable between a closed position where the sealing member engages with the sealing surface and an open position where the sealing member disengages from the sealing surface to allow flow through the inlet into the inner chamber. A cam is coupled to the valve head. Rotation of the cam causes movement of the valve head between the first position and the second position to move the valve head to the first position to hold the sealing member in the closed position.

Peristaltic pumps are described herein. In certain embodiments, a peristaltic pump includes a plunger, a first biasing member, and a second biasing member. The plunger is movable to selectively engage a pumping volume of a tubing segment to expand the pumping volume to draw fluid flow into the pumping volume and to contract the pumping volume to conduct fluid flow from the pumping volume. The first biasing member is configured to urge the plunger toward the tubing segment to maintain contact with the tubing segment during the expansion of the pumping volume. The second biasing member is configured to urge the plunger toward the tubing segment to contract the pumping volume.

A drive assembly and system include a drive, controllable to exhibit a selected one of a plurality of drive modes that include driving the drive in one of a first driving direction and a second driving direction, the second driving direction being directed opposite relative to the first driving direction, a pump that is drivable by the drive and configured to produce a hydraulic flow to flow in a flow direction independent of the first or second driving direction of the selected drive mode, and a control valve that is configured to be set in a valve position associated with the selected drive mode and configured to thereby direct the hydraulic flow produced by the pump depending on the selected drive mode of the drive along a selected one or more of a plurality of flow paths that are arranged downstream of the pump.

Pump subsystem for fluid delivery (e.g., in a wearable patch pump) comprises a fluid chamber with pumping motion and a valve shaft assembly with valving motion, both being driven by the same drive mechanism. Fluid chamber has variable volume chamber provided by a piston driven by the drive mechanism and translated relative to a plug in the pump housing. Piston extends the fluid chamber during an intake stroke and retracts the fluid chamber during a discharge stroke. Valve assembly has at least one valve shaft controllably translated by the drive mechanism to selectively align a first throughway with an opening in the pump chamber and a fluid intake port for an intake stroke to draw fluid into the fluid chamber, and align a second throughway with the opening in the pump chamber and a fluid discharge port for an discharge stroke to discharge fluid from the fluid chamber.

A fluid system may include a first fluid path including a blender configured to mix fluid with proppant. The fluid system may include a second fluid path, fluidly isolated from the blender, including a pump. The fluid system may include a mixing pump configured to receive first fluid containing proppant from the first fluid path and second fluid free of proppant from the second fluid path. The mixing pump may include a cylinder defining a bore. The mixing pump may include a first intake valve configured to control flow of the first fluid, a second intake valve configured to control flow of the second fluid, and an outlet valve configured to control flow of a mixture of the first fluid and the second fluid.