Abstract: An actuator unit includes two chambers defined in the cylinder; a supply passage allowing a working fluid discharged from the pump to be supplied to the two chambers; a discharge passage allowing the two chambers to communicate with the tank; a direction control valve configured to selectively communicate each of the two chambers with one of the pump and the tank; a control passage that branches from the supply passage on a side of the pump rather than the direction control valve so as to communicate the pump with the tank; a variable relief valve provided on the control passage, the variable relief valve opening so as to allow the working fluid to flow from the supply passage toward the tank when a pressure in the supply passage reaches the valve opening pressure; and a center passage that communicates the tank with an interior of the cylinder.

Abstract: A cylinder device includes a recess provided on either one of the piston and the cylinder, the recess facing the other one of the piston and the cylinder; an extension-side discharge passage configured to permit only a flow of liquid from the extension-side chamber toward the recess; a compression-side discharge passage configured to permit only a flow of liquid from the compression-side chamber toward the recess; a tank-side discharge passage configured to allow the extension-side discharge passage and the compression-side discharge passage to communicate with the tank through the recess; an extension-side damping force generation passage configured to apply a resistance to a flow of liquid passing therethrough so as to exert a damping force during extension; and a compression-side damping force generation passage configured to apply a resistance to a flow of liquid passing therethrough so as to exert a damping force during contraction.

Abstract: A vented pressurized gas-powered actuator includes a housing having a central longitudinal axis and an inner surface. The inner surface has a constant radius between first and second planes extending perpendicular to the axis. At least one vent groove extends from the inner surface in a direction away from the axis. The at least one vent groove has a first end intersecting the first plane and a second end intersecting the second plane.

Abstract: The invention belongs to the field of single-effect hydraulic cylinders. It relates to a device that makes it possible to limit the pressure in the pressurization chamber of a single-effect cylinder when the rod thereof is in a particular range of longitudinal positions of safety, while respecting the operating safety of the device, that is, in the case that the power supply of the pilot valves of the distributors and of the hydraulic pump is cut, the rod of the cylinder remains in its position if this position does not lie within the safety position range.

Abstract: A control device for the position control of a hydraulic cylinder unit has a controller which receives a set and an actual piston position and determines a preliminary manipulated variable based on the difference of the set and actual positions. A linearization unit multiplies the variable with a linearization factor and outputs it to the valve control unit so that the piston is adjusted at an adjustment speed. The linearization unit determines the factor dynamically as a function of the actual piston position and of working pressures that prevail at both piston sides. The linearization factor is determined such that a ratio of the adjustment speed to the difference of the set and actual positions is independent of the actual position and the working pressures. In the specific case where the controller is configured as a P controller, the order of the controller and the linearization unit can be reversed.

Abstract: The invention belongs to the field of single-effect hydraulic cylinders.

Abstract: An electro hydraulic servo valve assembly has a valve housing and a spool rotatably fitted to the inside of the housing. A number of ports are off-settedly provided along the length of the valve housing A plurality of orifices are provided along the length of the spool. The positioning of the orifices and the ports are such that only one set of orifices may be aligned with a corresponding set of ports at any one time. The spool has one end coupled to a servo motor so that the servo motor may drivingly rotate the spool relative to the valve body. The other end of the spool is open so that a fluid passage is established between the interior of the spool and any one of the orifices. When a particular orifice, or selected orifices, is/are in alignment with one or more corresponding ports, a fluid path is established between the spool and the valve body.

Abstract: The invention provides a rotary actuator having a rack driven in an oscillating manner by an air pressure, a pinion engaged with the rack, and a cushion mechanism for stopping the rack to at least one normal or inverse stroke end in a cushioning manner. The cushion mechanism has an exhaust port open to a pressure chamber at a position close to a chamber end rather than a port hole, a flow amount adjusting mechanism for restricting a flow amount of the exhaust air discharged from the exhaust port, and a cushion packing mounted to an outer peripheral surface of the piston and operating so as to shut the port hole from the pressure chamber immediately before the piston reaches the stroke end, thereby discharging the air within the pressure chamber through the flow amount adjusting mechanism.

Abstract: The hydraulic system for actuation of the mud valve of a measurement-while-drilling tool is characterized by a hydraulic actuator having a piston operatively connected to the mud valve of a measurement-while-drilling tool, which hydraulic actuator incorporates an internal by-pass which, cooperatively with movement of the piston, opens to unload hydraulic pressure from the system at either end of stroke of the piston. Return from the by-pass to the pump may be restricted so as to maintain some hydraulic pressure on the piston at end of stoke so as to prevent movement therefrom by external forces. The hydraulic system may include high pressure means, strainer means and means to equalize pressure between hydraulic system pressure and pressure external of the system.

Abstract: Vehicle suspension apparatus operating between the sprung and unsprung masses of a vehicle includes a pendular anti-roll bar connected to the vehicle, and a pair of links which connect the bar to the wheels. One and the other link, respectively, is extensible and inextensible, with the extensible link comprising a selectively controllable hydraulic piston-cylinder assembly having first and second flow paths, and valve means which upon command automatically locks the piston at a midstroke position, depending on the flow of fluid in the passages. The flow paths allow the user to select either of two roll stiffness levels (i.e., high and low) and provide automatic convergence of the piston to its locked midstroke position (high roll stiffness hard ride) upon command.

Abstract: An improved hydraulic door actuator comprising a hydraulic fluid pump having first and second ports; integral operating cylinder and fluid control apparatus including a barrel coupled at each end to the first and second ports of the hydraulic fluid pump; a piston fluidly sealed within the barrel; and means for controlling the flow of fluid of the hydraulic fluid pump to and from the barrel disposed between the barrel and the first and second ports such that the door automatically slows to a stop upon opening or closing wherein the fluid flow control means comprises a plurality of openings disposed along the length of the barrel for bypassing pressurized fluid from the barrel.

Abstract: A hydraulic door opening or closing device comprises a hydraulic fluid pump motor having two ports connected to each end of integral dual manifold and operating cylinder apparatus by way of two branch fluid lines. One branch line is fluidly connected to a particular end of the operating cylinder by way of a directional flow valve. The other branch line to the same end of the cylinder is fluidly connected to the cylinder by way of an associated manifold. Fluid communication with the cylinder through the manifold is accomplished by providing a plurality of valved openings linearly disposed along the end of the cylinder between the manifold and the cylinder. As a piston of the operating cylinder passes these openings, a door coupled to the piston is automatically slowed as fluid on the drive side of the piston is returned through the openings to the hydraulic fluid pump.

Abstract: The device for controlling the displacement for a moving member such as a flap (46) includes a fluid distributor valve (10) actuated by control means (18) and suitable for connecting a single-action actuator (38) to a source of fluid under pressure, or to an exhaust, or for isolating said actuator from said source and said exhaust. The piston rod (40) of the actuator is connected to a moving element (14) of the distributor valve and also to the moving member (46) by common motion transmission means. The invention is applicable, in particular, to controlling flaps in installations for heating and ventilating or for air conditioning motor vehicles.

Abstract: A fluid flow selector valve for controlling step-by-step displacement of an on/off actuator (12), e.g. for controlling a flap in an installation for heating or for air conditioning the cabin of a motor vehicle. The valve comprises two mutually movable elements (80, 84) defining at least two chambers (90, 92) therebetween suitable for connecting the actuator feed inlet (30) to a source of fluid pressure (72) or to an exhaust. The valve further comprising an intermediate chamber (94) suitable for connecting the feed inlet to the source of fluid pressure (72), to the exhaust, or to an air tight seal.

Abstract: Step control apparatus for a fluid motor includes a plurality of devices each responsive to an external signal for initiating movement of the fluid motor. Also included is a mechanism for stopping movement of the fluid motor upon movement thereof a discrete step. Thus, a sequence of external signals applied to the devices effects movement of the fluid motor in a stepping mode. Optionally, an assembly may be provided for effecting movement of the fluid motor in a free-running mode.

Abstract: An air conditioner of a vehicle having a selectively controlled conditioned air blowing outlet system using a shift actuator (20) equipped with a number of negative pressure supplying ports (a, b, c, d), in which selection of the operation mode of the conditioner is represented by the supply of a negative pressure signal to any one of the supplying ports, which causes displacement of a piston (31) of the shift actuator (20). The displacement is conveyed to selected one or more of doors provided at the outlets via a link mechanism to control the outlets according to a predetermined program.

Abstract: A flashlamp unit having a plurality of flashlamps secured to a support on which an electrical circuit is printed. The flashlamps are connected to the circuit which includes break switches. The support with the electrical circuit and break switches has such a construction that the electrical conductors of the break switches and the circuit can be provided in the same operational step.

Abstract: A step-by-step controlled servomechanism of the type comprising a drive element movable provided with a plurality of receiver ports, and a fixed distributor to supply said receiver ports and having a number of transmitter ports capable of being connected, in pairs, respectively to the low pressure and to the high pressure, a fixed manifold having a plurality of manifold ports capable of communicating with the chamber of the drive element, all the receiver ports being capable of being made to open in succession into one of said manifold ports, selecting means capable of connecting, in succession by permutation and simultaneously, at least one pair of transmitter ports to the high pressure and to the low pressure, respectively, and at least one manifold port to the chamber of the drive element.

Abstract: A pneumatic adjusting mechanism, especially for application in motor vehicles, which consists of a suction-air servo-motor that includes a working cylinder with a diaphragm piston whose piston rod is stressed by a spring against the action of the suction-air; to provide an adjustment to different adjusting path steps, individual control lines are connected to the working cylinder in places which correspond to the adjusting path steps; all control lines lead to a control switch connected with a suction-air reservoir line while each individual control line is adapted to be selectively connected with this suction-air reservoir line, after previous venting of all control lines, by means of the control switch.

Abstract: Step by step controlled servomechanism of the cylinder-type comprising a drive element movable in a case which it divides into two chambers and provided with a plurality of receiver ports, a distributor adapted to be put in communication with the high pressure and the low pressure and to supply said receiver ports, wherein said distributor is fixed and provided with a number of supply or transmitter ports at least equal to three but independent of the number of receiver ports, the transmitter ports being capable of being connected by permutation, in succession and in pairs, respectively to the low pressure and to the high pressure, the distance between the receiver ports and their length, on the one hand, the distance between the transmitter ports and their length, on the other hand, being such that, by the step by step displacement in one direction of the drive element, on one hand, it is possible to bring each time at least one receiver port between the two transmitter ports of a pair in such position that