A rotary valve rotated by an arm connected to a piston being driven by the pressurized fluid, either water or air. The orientation of the valve body in the valve housing will direct the fluid in one of two directions to move the piston. The arm of the rotary valve is connected to a cam that rotates a shaft connected to the valve body. Two cam rollers are biased towards the outer surface of the rotating cam member. The cam rollers provide a force to the cam to aid in the changing of the orientation of the valve body. There are two bump outs on the cam that correlate to the end of the piston movement so that the rotary valve does not stop at an end point of the piston stroke. The rotary valve may be is utilized in a chemical dosing or chemical application device that is driven by pressurized fluid.

In a high pressure fuel supply system, a variable speed motor asynchronously actuates a pumping piston with a drive mechanism including a circular cam with cam roller, having an axis that is offset from the axis of the cam drive shaft. A rolling or sliding cam follower is rigidly connected to the piston, and a piston retainer is operatively connected among the piston, the cam follower and the cam roller. As the cam shaft rotates, the cam roller rotates eccentrically relative to the cam shaft while maintaining contact with the cam follower, thereby reciprocating the follower and the piston along the actuation axis, in corresponding charging and pumping strokes of the piston.

An injector generator for use in geomechanical pumped storage systems includes a power end and a fluid end. The fluid end has one or more fluid chambers each having a fluid inlet and outlet that are controlled by rotary valves. The fluid end can function as a pump or as a motor driven by fluid pressure from the geomechanical storage formation.

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.

A device for conserving power is provided in a piston compressor, in particular a piston-compressor for generating compressed air in a motor vehicle and having a piston delimiting a compression chamber for generating compressed air, which, originating from the ambient environment, arrives in the compression chamber for compression by way of at least one suction connection formed on a cylinder head cover and an intake valve array arranged on a valve plate. For the purpose of conserving power, a pressure-dependently acting idling device is provided for the intake valve array having a dedicated suction lamella, which can be rotated by an actuator between a working position overlapping at least one suction opening and an idling position unblocking, at least in part, the at least one suction opening. The actuator actuates the suction lamella in a coordinated manner such that in the idling position, the suction lamella unblocks the at least one suction opening in the valve plate, at least partially, while simultaneously blocking adjacent pressure valve cross-sections, at least partially, and locks the suction connection at the cylinder head cover by a slider in order to form an increased dead space in the area of the cylinder head.

A piston pump for a traction-controlled hydraulic vehicle braking system includes a pump piston and an annular piston that is arranged as a second piston in a resiliently loaded manner on the pump piston. As the delivery pressure increases, a resilient element is compressed and a stroke of the second piston is shortened so as to reduce a delivery quantity. This configuration enables a higher delivery pressure to be achieved for a given driving force. With low delivery pressure, the pump piston and the second piston deliver together so as to achieve a rapid build-up of pressure.