A fluid pump for a linear actuator is provided. The pump causes a rod in the actuator to extend or retract by controlling the flow of fluid to and from portions of a fluid chamber on either side of a piston disposed within the fluid chamber and supporting the rod. The pump includes a valve structure that enables the pump to redistribute fluid obtained from one portion of the fluid chamber on one side of the piston to the other portion of the fluid chamber on the other side of the piston without first returning the fluid to a fluid reservoir thereby increasing the efficiency of the pump.

Many devices with limbs or arms are susceptible to damage when a user bends or twists a joint of the limb or arm beyond its design point or in a direction other than intended. This is common with children's toys. Accordingly, it would be beneficial to provide children with toys employing fluidic actuators that can be bent, twisted, deformed and yet recover subsequently allowing the intended motion to be performed. Further, it would be beneficial by providing devices that employ fluidic actuators, and hence are essentially non-mechanical, to provide users not only of toys but other devices with driving mechanisms that are not susceptible to wear-out such as, by stripping drive gears, etc., thereby increasing their reliability and reducing noise. Fluidic devices allow for high efficiency, high power to size ratio, low cost, limited or single moving part(s) and allow for mechanical springless designs as well as functional reduction by providing a piston which is both pump and vibrator.

A system and method for machinery performing work with hydraulic actuators. Radial hydraulic pumps are aligned end-to-end along a common driveshaft axis to form a multi-pump assembly having a plurality of piston/cylinder units extending in a radial direction. Two or more piston/cylinder units are associated with one another to form multiple piston/cylinder groups. A plurality of control valves combines individual output flows from the two or more associated piston/cylinder units into respective common output flows for each respective piston/cylinder group. A plurality of flow control devices varies the common output flow from each respective piston/cylinder group by throttling inlet flow to the two or more associated piston/cylinder units in each respective piston/cylinder group. Each respective common output flow is directed from each respective piston/cylinder group to a hydraulic actuator on the heavy machinery to control its direction of movement.

A hydraulic power unit includes a reservoir containing hydraulic fluid, a main output, a pressure sensor, at least one active valve hydraulic pump and at least one passive valve hydraulic pump. A main flow of the hydraulic fluid is discharged through the main output. The pressure sensor includes a pressure signal that is indicative of a pressure of the main flow. Each active valve hydraulic pump is configured to drive a first flow portion of the main flow from the reservoir to the main output when the pressure signal is below a first pressure setpoint. Each passive valve hydraulic pump is configured to drive a second flow portion of the main flow from the reservoir to the main output when the pressure signal is below a second pressure setpoint.

A linear actuator system includes a linear actuator and an integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with two fluid drivers, each fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes the pump in a normal mode of operation in which the prime movers are independently driven and switches to a fail-safe mode of operation in which only one prime mover is operated.