Abstract: A fluid pressure control apparatus includes a proportional solenoid valve operatively connected between a fluid inlet and a fluid outlet and a pressure sensor fluidically coupled to the fluid outlet, wherein an electronic controller generates and outputs a control signal to the solenoid valve in dependence on a first signal from the pressure sensor and a second signal corresponding to a pressure set point, where the solenoid valve has a rest position between opened and closed, and the electronic controller is further adapted to generate the control signal with either of opposite polarities to move the valve in either of opposite directions from its rest position in order to reduce power consumption and heat generation, in particular for use in gas analysis equipment located in hazardous areas.

Abstract: A remote controlled demolition robot (10) comprising a controller (17) and at least one actuator (12) controlled through a hydraulic system (400) comprising at least one valve (13a) connected to a corresponding actuator for a tool (11b) and a pump (410). The controller (17) is configured to operate in a first mode wherein the fluid flow is controlled through the at least one valve (13a), wherein said valve (13a) is a proportional valve, receive a pressure indication indicating a pressure in the hydraulic system (400) and determine if the pressure in the hydraulic system (400) is above a first mode threshold and/or if a pressure change fulfills a first mode condition, and if so operate in a second mode wherein the at least one valve (13a) is in an opened state and the fluid flow is controlled through the pump (410).

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: A pump jack drive apparatus includes a pair of hydraulic cylinders connected to a walking beam of the pump jack for reciprocating the horsehead, and a pair of microswitches or proximity switches which are closed by the walking beam at the limits of the stroke thereof for controlling such stroke. The cylinders are driven and controlled by a pump and control unit which includes a valve for feeding hydraulic fluid to one or the other of the hydraulic cylinders, a control cylinder for controlling the valve, and two solenoid operated control valves for controlling movement of the control cylinder in response to closing of the switches by the walking beam.

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 transfer system having a transfer mechanism which is located directly on or adjacent the production machine. The transfer mechanism comprises a reciprocating workpiece shuttle driven by a hydraulic driving unit, specifically a hydraulic transfer cylinder. The latter is connected to a remote hydraulic cycloidal drive unit by long conduits which may be positioned overhead. The remote hydraulic cycloidal drive unit employs a pumping cylinder having an elongated stationary piston rod on which the cylinder housing is slidably supported, with the pressure fluid from the pumping cylinder being supplied through the conduits to the transfer cylinder. The housing of the pumping cylinder is reciprocated by a crank associated with a cycloidal mechanical drive. This crank is connected to and rotates with a gear which is rotatably supported on a slide and reacts with a stationary rack so that reciprocation of the slide causes alternate rotation of the gear.

Abstract: A hydraulically operated oil well pump jack utilizing a double acting hydraulically operated piston and cylinder assembly for pivoting the walking beam of an oil well pump jack, a linkage mechanism for operating a reversing valve to cause extension and retraction of the piston and cylinder assembly for oscillating the beam about a saddle bearing at the upper end of a stanchion or samson post together with a crossover cushioning device for controlling acceleration and deceleration of the oscillating walking beam to reduce abrupt tension forces exerted on the polish rod and sucker rods and also reduce impact forces on the oil well pump jack during oscillation of the walking beam.

Abstract: A fixed platen is supported in the machine frame, and a movable platen is connected to two parallel rods which project rearwardly through the fixed platen. Each rod carries a first piston and each piston is slidably received in a first cylinder. These cylinders are slidably received on the rods and each cylinder has a forward end defining a second larger piston slidably received in a fixed second cylinder. The front and rear faces of the smaller pistons are selectively connected to fluid from a first pump through a synchronizing valve, and a paralleling pump supplements the flow from the first pump during synchronization, that is during the major part of the mold opening and closing movement. Slower movement is provided for just prior to the platen reaching the mold open and closed positions.

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.