A variable displacement linkage mechanism includes a slider mechanism, a cam, a connecting link, a rocker link, and a cam follower. The connecting link is coupled to the slider through a first revolute joint. The rocker link includes a rocker end and a ground end. The rocker end is coupled to the connection link through a second revolute joint, and the ground end is coupled to ground through a third revolute joint. The cam follower is coupled to the connecting link and engages the cam. A location of the third revolute joint is adjustable relative to the first revolute joint.

In one aspect, there is provided a damper control system for a reciprocating pump assembly according to which control signals are sent to electromagnets. In another aspect, there is provided a method of dampening vibrations in a pump drivetrain according to which a beginning of torque variation is detected and at least a portion of the torque variation is negated. In another aspect, signals or data associated with pump characteristics are received from sensors, torque characteristics and damper response voltages per degree of crank angle are calculated, and control signals are sent to electromagnets. In another aspect, a damper system includes a fluid chamber configured to receive a magnetorheological fluid; a flywheel disposed at least partially within the fluid chamber and adapted to be operably coupled to a fluid pump crankshaft; and a magnetic device proximate the flywheel. The magnetic device applies a variable drag force to the flywheel.

A hydraulic radial piston device is provided with a mechanism for reducing pressure pulsations and providing a smooth pressure transition throughout different displacement operations. In certain examples, the hydraulic radial piston device is configured to maintain an amount of precompression and an amount of decompression of hydraulic fluid trapped in a cylinder chamber to be consistent, respectively, throughout different displacement operations.

A hydraulic radial piston device is provided with a mechanism for reducing pressure pulsations and providing a smooth pressure transition throughout different displacement operations. In certain examples, the hydraulic radial piston device is configured to maintain an amount of precompression and an amount of decompression of hydraulic fluid trapped in a cylinder chamber to be consistent, respectively, throughout different displacement operations.

Provided is a variable capacity pump where ease of control can be improved. A variable capacity pump includes a control chamber and a control valve. The control chamber is disposed between a pump accommodating chamber and a movable member, and the volume of the control chamber is variable with the movement of the movable member. Working oil discharged from a discharge portion is introduced into the control chamber. The control valve is provided in a passage and, with the movement of a valve element, the control valve varies the cross-sectional area of a flow passage, through which working oil in the control chamber is drained to a low pressure portion, while making the discharge portion and the control chamber communicate with each other.

In one aspect, there is provided a damper control system for a reciprocating pump assembly according to which control signals are sent to electromagnets. In another aspect, there is provided a method of dampening vibrations in a pump drivetrain according to which a beginning of torque variation is detected and at least a portion of the torque variation is negated. In another aspect, signals or data associated with pump characteristics are received from sensors, torque characteristics and damper response voltages per degree of crank angle are calculated, and control signals are sent to electromagnets. In another aspect, a damper system includes a fluid chamber configured to receive a magnetorheological fluid; a flywheel disposed at least partially within the fluid chamber and adapted to be operably coupled to a fluid pump crankshaft; and a magnetic device proximate the flywheel. The magnetic device applies a variable drag force to the flywheel.

The present invention is directed to an improved liquid additive injection pump that of a type wherein a variety of additive volumes may be metered into a fluid stream or fluid source by adjusting the plunger stroke with an easily accessible adjustment bushing without changing or interrupting, the power supplied to the pump during operation. A robust roller bearing drive is used to power the plunger(s) providing fluid suction and discharge as the plunger(s) cycle, while ensuring accurate and reliable additive injection rates. A spring energized seal eliminates overtightened packing by field technicians. An easily accessible adjustment bushing allows the user to modify the piston stroke length, thereby increasing, decreasing or stopping the volumetric flow of injected additive into a fluid stream or storage container.

A crank-piston mechanism for a reciprocating double-acting piston-type gas compressor that allows for infinitely variable compression ratios during operations. The mechanism includes a gear pin crankshaft, a forward piston-connecting rod, a rearward piston-connecting rod, a forward crosshead, a rearward tubular crosshead, and a tandem piston assembly. The forward piston-connecting rod and the rearward piston-connecting rod are each rotatably connected to the gear pin crankshaft about two parallel but offset axes. On the opposite end, the forward piston-connecting rod and the rearward piston-connecting rod are connected to the forward crosshead and the rearward tubular crosshead, respectively. Wherein, the forward crosshead is slidably mounted within the rearward tubular crosshead. The forward crosshead is connected to a forward piston from the tandem piston assembly and the rearward tubular crosshead is connected to a rearward piston from the tandem piston assembly. The forward piston and the rearward piston are aligned for reciprocating motion.

A crank-piston mechanism for a reciprocating double-acting piston-type gas compressor that allows for infinitely variable compression ratios during operations. The mechanism includes a gear pin crankshaft, a forward piston-connecting rod, a rearward piston-connecting rod, a forward crosshead, a rearward tubular crosshead, and a tandem piston assembly. The forward piston-connecting rod and the rearward piston-connecting rod are each rotatably connected to the gear pin crankshaft about two parallel but offset axes. On the opposite end, the forward piston-connecting rod and the rearward piston-connecting rod are connected to the forward crosshead and the rearward tubular crosshead, respectively. Wherein, the forward crosshead is slidably mounted within the rearward tubular crosshead. The forward crosshead is connected to a forward piston from the tandem piston assembly and the rearward tubular crosshead is connected to a rearward piston from the tandem piston assembly. The forward piston and the rearward piston are aligned for reciprocating motion.

A pump assembly comprises a base, a cam, a cylinder, a piston, and a shim clip. The cam rotates about a rotational axis with respect to the base. The cylinder attaches to the base, and has an inlet port and an outlet for fluid. The piston is reciprocally driven by rotation of the cam to draw fluid into the cylinder through the inlet port during a fill stroke, and to close the inlet port and pump fluid in the cylinder toward the offset during a pump stroke. The shim clip is removably insertable between the cylinder and the base to increase the distance between the inlet port and the rotational axis.