Abstract: A wind turbine generator, or other energy extraction device, has a hydraulic circuit comprising a hydraulic pump driven by a rotating shaft and a hydraulic motor driving an electricity generator. When the electricity generator is switched off, it executes one or more pumping cycles to pressurise the high pressure manifold and therefore recover angular kinetic energy from the electricity generator rotor which can later be used to reaccelerate the electricity generator rotor to the correct operating speed for an electricity grid. Overall energy efficiency is increased and the minimum operating high pressure manifold pressure may be reduced as a result.

Abstract: A system and method for controlling shakability of a work tool. A series of input commands from a control unit to the hydraulic pump cause the hydraulic pump to cycle between a first displacement (maximum) at a first rate (maximum) and a second displacement (zero) at a second rate (less than maximum), within a predetermined frequency. Ultimately, the hydraulic pump remains in a partially upstroked position at the beginning of every cycle. Accordingly, within a small fraction of time after upstroking, the pump is capable of providing full flow to the actuators, resulting in much faster response and movement of the actuators, and therefore improved shakability of the work implement.

Abstract: A system and method for controlling shakability of a work tool. A series of input commands from a control unit to the hydraulic pump cause the hydraulic pump to cycle between a first displacement (maximum) at a first rate (maximum) and a second displacement (zero) at a second rate (less than maximum), within a predetermined frequency. Ultimately, the hydraulic pump remains in a partially upstroked position at the beginning of every cycle. Accordingly, within a small fraction of time after upstroking, the pump is capable of providing full flow to the actuators, resulting in much faster response and movement of the actuators, and therefore improved shakability of the work implement.

Abstract: A hydraulic system for retracting into and extending out of the body of an aircraft a landing gear for use in taking off and landing, comprises a housing unit which has a hydraulic pump, a hydraulic actuator, a shuttle valve, an emergency valve, an actuator pressure releasing mechanism, and a mechanically locking mechanism accommodated therein. The hydraulic actuator has a piston rod assembly received therein to be reciprocably moved by the hydraulic pump to assume a retraction position and an extended position. The shuttle valve is movable with respect to the housing unit for selectively changing the flow of the hydraulic fluid between the hydraulic pump and the hydraulic actuator. The emergency valve is movable with respect to the housing unit to assume two different positions for selectively changing the flow of the hydraulic fluid between the hydraulic pump and the hydraulic actuator and the flow of the hydraulic pump and the fluid pressure reservoir.

Abstract: A Hydraulic Pumping Unit equipped with a flywheel, a high-slip electric motor and a reversible hydraulic pump such that during the downstroke of the Unit, the hydraulic pump operates as a hydraulic motor, accelerating the flywheel and accumulating in this way the energy of the downgoing rodstring in the form of kinetic energy.The interaction between the flywheel, electric motor and weight of the rodstring adjusts automatically the range of speed variation.The upward and downward speeds of the Hydraulic Pumping Unit can be adjusted by hand or automatically by electronically commanded step motors, in such a way that the Hydraulic Pumping Units adjusts itself to the varying conditions of the oilwell.

Abstract: The invention involves pressure-counterweighted oil-well pumping apparatus in which derrick structure of elemental simplicity involves components which are readily assembled and disassembled, such that a given pumping apparatus can be loaded on a single truck and transported from one to the next desired well-pumping location. For a given capacity pumping system, overall height requirements for the derrick structure are less than one half those of U.S. Pat. No. 4,631,918. And power-integrator complexity is substantially reduced by employment of a fixed-displacement variety in conjunction with a variable speed a-c motor as the prime mover, under control of solid-state devices and pressure-sensitive transducer elements which determine upper and lower limits of the reciprocating stroke.

Abstract: A slurry pump has slurry hopper and dual pumping cylinders. The slurry pumping members are driven by opposite-phase actuators. Each actuator has a rigid-hollow-stem partition dividing the space between the actuator plunger and the cylinder into two drive chambers of different areas selectively supplied with pressurized fluid to drive the plunger with a selected force and speed. An associated valve shuts off flow to one of the drive chambers and is controlled at any given time to occupy the same position as a corresponding valve of the other actuator. The valves coordinate supply of fluid to corresponding drive chambers on alternate strokes of two actuators.

Abstract: A flat, elongate, laminated plate of ceramic piezoelectric material is fixedly mounted on one end to permit movement of the other end responsive to the application of a variable electronic control signal to electrodes on the outer surfaces of the laminated plate. The movement and force applied by the movable end of the plate controls the release of air pressure from the pressure chamber so that the pressure in the chamber varies in response to the variations of the electronic control signal.

Abstract: A pumping apparatus is disclosed which uses a reversible, variable displacement hydraulic drive pump capable of pumping fluid under pressure. A hydraulic cylinder enclosing a piston is operatively connected to a port of the hydraulic drive pump. A fluid accumulator, which is precharged to a selected precharge pressure, is operatively connected to the other port of the hydraulic drive pump. The fluid accumulator supplies the fluid under the precharge pressure to the hydraulic drive pump. The hydraulic drive pump increases the pressure on the fluid to a working pressure required to drive the piston from a first position in a first direction to a second predetermined position. Upon reaching the second position, the hydraulic drive pump reverses direction to reverse the flow of fluid from the hydraulic cylinder thereby reciprocating the piston back to its first position, and directing the fluid to the fluid accumulator.

Abstract: A pumping apparatus includes a reversible variable displacement drive pump having two ports and a lifting apparatus connected to one of the ports. The lifting apparatus is designed to fit on the well-head of an oil well and attach to the polish rod of the well to operate a down-hole pump. A fluid accumulator containing a precharge is connected to the second port of the drive pump. A pump-off control system automatically adjusts the pumping rate of the lifting apparatus to the individual rate of formation flow of a particular well.

Abstract: The pump or pumps for supplying fluid to the two ends of a double-acting cylinder include a direction control, such as a direction control valve, shiftable between extend and retract conditions. A drive mechanism for the direction control includes a rotary hydraulic motor and a driven rotary drive mechanism for shifting the direction control. Hydraulic fluid is supplied to the drive motor through parallel connected start and stop valves. The start valve is opened in response to the movements of the hydraulic cylinder toward a stroke limit. The stop valve is operated in response to the shifting of the direction control, so that the motor is operated intermittently to reverse the direction control when the cylinder reaches the limit of an extend or retract stroke. The stop valve is controlled by the drive mechanism in timed relation with the shifting of the direction control. The start valve may be closed by that drive mechanism in timed relation with the opening of the stop valve.

Abstract: A hydraulic drive apparatus for a wellhead pump jack which utilizes oppositely driven single-acting hydraulic cylinders as actuated by a variable volume pump having flow direction and flow volume controlled by a servo linkage and control lever. The linkage transmits oscillatory sine function motion of the walking beam for movement of the control lever as intermediate biasing force prevents nulling of the system.

Abstract: The preferred embodiment is directed to an oil well pumping apparatus incorporating a walking beam having a horsehead at one end which connects to the sucker rods in the oil well. The opposite end of the walking beam is supported on a fixed pivot. A hydraulic and pneumatic combination unit connects from a supporting platform to a central point on the beam to raise and lower the beam. The improved apparatus utilizes air pressure to balance the static load on the apparatus and dynamically strokes the sucker rod string by imparting a reciprocating motion through hydraulic power applied at a specified rate to raise and lower the walking beam. A pump and motor system for a closed hydraulic loop is included. Alternate preferred embodiments are disclosed. In one form, a lubricating system is incorporated. First and second alternate forms of pickoff apparatus which powers the pneumatically balanced pumping apparatus is also included.

Abstract: An oil well pump drive including a drive unit that is hydraulically actuated by a double-acting hydraulic cylinder to reciprocate vertically. An endless chain is entrained over vertically spaced sprockets carried by the unit, with one flight of the chain anchored against vertical movement and the other flight is secured to the pump polish rod so that the vertical motion imparted to the polish rod is double that hydraulically imparted to the drive unit. The polish rod load on the chain is opposed by a counterweight connected thereto by a chain extending over an elevated pulley. The output of the hydraulic pump supplying the hydraulic cylinder is cam controlled so that the motion of the drive unit is smoothly decelerated and accelerated as the unit approaches and moves from the upper and lower limits of its movement.

Abstract: A pump jack, such as the type capable of use in pumping crude oil from an oil well, the pump jack including a double acting piston and cylinder motor with the piston rod of the motor being adapted to be connected to the polished rod projecting upwardly from a well head. A variable displacement hydraulic pump, which is driven by a motor or engine, is included in a closed hydraulic loop wherein conduits are connected to a pair of output ports of the pump. A pump control means controls the direction and volume of flow in the loop so as to establish the stroke of the piston rod. A compressible fluid counterbalance is provided for accumulation of energy during a down stroke of the piston rod so that the energy may be returned to the piston during the up stroke. An economical and versatile unit may be produced by mounting a counterbalance cylinder coaxially above the motor and providing the counterbalance with an additional closed chamber in fluid communication with a charged chamber of the counterbalance.

Abstract: An improved hydraulic drive system for a doubleacting hydraulic cylinder which drives or rocks the walking beam of an oil well pump. A closed circuit hydrostatic drive system is used to operate the double-acting hydraulic power cylinder unit and includes a variable displacement reversing swashplate pump driven at a predetermined constant speed by a prime mover such as an electric motor. Suitable automatic control means are provided for synchronizing the reversing movement of the swashplate with the rocking movement of the walking beam.

Abstract: An illustrative system is disclosed for use as a rotary-drive engine, utilizing combustible fuel and a hydraulic system of energy conversion. An engine block defines a pair of expansion cylinders (combustion chambers) and an associated concentric pair of hydraulic chambers. The chambers matingly receive unitary piston structures for phase-opposed reciprocal movement.The hydraulic working chambers communicate with each other and can exhaust high pressure fluid through a control valve structure for drive power. Exhausted fluid is replaced in volume by low-pressure spent fluid. The body of the fluid contained in the hydraulic working chambers along with the piston means and springs connected to the engine block define an oscillatory system which is resonant at the operating frequency. That consideration, along with the absence of lateral loads on the pistons, results in relatively high efficiency.