Abstract: A power cylinder (10) has two pistons (12, 20) slidably mounted within separate cylinders (14, 22) to define inner and outer chambers (16, 18; 24, 26) within each cylinder. One or more rods (28) are coupled between the pistons. The outer chambers (18, 26) are coupled together to allow pressurized hydraulic or pneumatic fluid to flow therebetween. The inner chambers (16, 24) are coupled together to allow pressurized hydraulic or pneumatic fluid to flow therebetween. The fluid flow aforesaid may be achieved by using two hollow rods (128, 130) and allowing the fluid to flow through the rods between the respective chambers. A guard (44) may surround first and second cylinders (14, 22). Bearings (46, 48) may be fixed around the opposed inner ends of cylinders (14, 22) to allow slidable displacement of the cylinders relative to guard (44).

Abstract: The invention relates to a low-vulnerability device for the operation of a lifting and propulsing helicopter rotor by means of a cyclic plate mechanism, in which the non-rotating plate (5) is coupled at four points (1, 2, 3, 4) to four hydraulic actioning servocontrols each comprising a power jack (9), an anchoring system (10) and a servocontrol-distributor (41, 42), three servocontrols being used when normally working, the fourth being used in back-up in the event of a failure of one of the other three. Each power jack (9) is supplied by an independent hydraulic circuit which comprises the servocontrol-distributor (41, 42) operated by a mechanical input, connected to the cockpit by linkage (13), and a disengageable anchoring system.

Abstract: A speed control system for a working vehicle comprises a hydrostatic transmission for propelling the vehicle, a hydraulic cylinder and a control valve. The hydraulic cylinder includes a cylinder case operatively connected to a control shaft for varying a swash plate angle of the hydrostatic transmission, and a piston rod fixed to a case containing the hydrostatic transmission. The control valve is fixed to the cylinder case and includes a spool extending parallel to the hydraulic cylinder and operatively connected to a foot pedal for manually controlling the hydrostatic transmission. The cylinder case is shiftable following a shift of the valve spool.

Abstract: A hydraulically powered reciprocating downhole pump having improved means for reliable and efficient operation is disclosed in which a reversing valve (8) is hydraulically shifted past center position so as to effect a smooth continuous operation. Inlet valves (5) and outlet valves (86) are provided so as to most fully utilize space available within diameter constraints for rapid and efficient operation.

Abstract: In an electric furnace a lifting means actuating the furnace cover includes a king post supported on the base. The king post is surrounded by a sleeve, which is liftable and lowerable relative to the same and has a cap on its upper end. The sleeve is hydraulically liftable and engageable with a cover carrying framework carrying the furnace cover. In order to provide for a lifting means with a low weight without constraining forces and with a structurally simple lubrication, a cylinder space to which a hydraulic medium is admitted is provided between a front face of the king post and the cap of the sleeve acting in the lifting direction. If desired, an annular space is provided between a collar of the king post and the inner wall of the sleeve, to which a hydraulic medium is provided, acting in the lowering direction.

Abstract: The device comprises a directional valve body which is movable with respect to guide means, and a spool which is slidably mounted in the body and connected to a control lever. The latter is pivotally mounted on a pin which is fixed relative to the body. This pin is carried by a support which is mounted on the body and means are provided for adjusting the position of the support relative to the body.

Abstract: A power assist device for a control system to amplify force to assist in movement of control apparatus. Device has signal input device and directional valve which are both responsive to a control signal, and a fluid power cylinder assembly which is connectable to an input of the control apparatus to apply an amplified control signal thereto. The directional valve means controls fluid flow between first and second chambers on opposite sides of a piston of the power cylinder assembly so as to determine the direction of movement of the assembly in response to valve position. The signal input device has an indicator to indicate a particular control setting or datum for a control signal which can be felt by operator, which contrasts with prior art power assist device where feel of a particular setting location is lost.

Abstract: A servo booster assembly comprises a housing having a fixed part and a movable part defining a chamber therebetween, a control valve for communicating the chamber alternately with vacuum and ambient air, and an input member movement of which operates the control valve. In response to operation of the control valve the movable housing part moves relative to the fixed part between an inoperative position and an operative, brake-applying position, the movable part being connected to an output member. The housing parts are interconnected by a tie bar the ends of which extend outside the housing and are adapted respectively for connection to a master cylinder and a vehicle bulkhead.

Abstract: An installation for the servo-assist of actuating devices in motor vehicles, especially of a hydraulic brake system, in which a control member, such as the brake pedal, acts on an actuating device, such as a master cylinder of a two-circuit brake system by way of a servo-member; a hydraulically actuatable servo-unit is thereby arranged between the control member and the actuating device whose first part is supported at the control member and whose second part is connected with the actuating device; the actuation of the servo-unit is controllable from a hydraulic pressure medium source in the manner of a follower control by means of a control device connected with the control member.

Abstract: A fail-safe fluid control valve comprises a first sleeve accommodated in and fixed to a valve housing, a second sleeve slidably received in the first sleeve, and a valve spool slidably received in the second sleeve. The first and second sleeves are properly formed with grooves and ports while the valve spool is properly formed with spaced large diameter portions. When there occurs such an abnormal condition that the valve spool is jammed or stuck to the second sleeve, the second sleeve is axially moved in unison with the valve spool by an input lever for actuating the fail-safe control valve under the same condition as a normal condition in which the valve spool is axially moved by the input lever.

Abstract: An articulated fluid loading arm for delivery of gasoline or other liquids through a drop pipe into a tank truck or railway tank car. The arm is equipped with a control system comprising a hydraulic jack for regulating the angle defined by the inboard and outboard arm sections, a sensor system that senses a change in the attitude of these two arm sections and actuates the hydraulic jack to maintain the drop pipe in an established azimuthal position as it is lowered into and raised out of the tank truck or tank car hatch, and means for adjusting the sensor system to make it functional for various locations of the drop pipe.

Abstract: A conventional hydraulic braking system using a master cylinder and a force ooster means between the brake pedal and master piston. The force booster means comprises a liquid cylinder and control valve means for selectively communicating the cylinder with a hydraulic pressure source or drain, depending on the application or non-application of manual force to the brake pedal. The control valve is designed to regulate the cylinder movement in accordance with pedal movement while increasing the force applied to the master piston.

Abstract: A multiple servo system including two or more servo mechanisms, each having a pressure feed back including two pistons exposed in respective chambers interconnected by a low-pass hydraulic filter, in which the area of the two feedback piston faces differ by up to 25%. This reduces the tendency of the respective actuators to act in opposition and thus increases the service life of the system.

Abstract: Device for moving and positioning an element of a machine comprising a hydraulically controlled valve shaft sliding in a sleeve and two output ducts in which the oil pressure depends on the position of the valve shaft. The oil pressure in the two output ducts is supplied respectively to two compartments of a hydraulic jack which positions and moves the carriage or slide of a machine tool. Two control chambers in between the valve shaft and sleeve jack include a constant volume part formed between shoulders on the valve shaft and a variable volume part formed by a slidable piston inside of a longitudinally extending cylindrical cavity inside the valve shaft. The cylindrical cavities extend to respective outer ends of said valve piston with fixed stops attached to the sleeve ends. The valve shaft is mechanically coupled to the mobile unit with the jack by a spring biased lost-motion pivot lever connection.

Abstract: A control device for a steering mechanism of a vehicle includes hydraulic means for laterally pivoting a pair of independently suspended guide wheels in response to rotation of a steering wheel of the vehicle. The hydraulic means includes a pair of double-acting jacks attached to respective guide wheels in such a manner that the extension of each jack pivots a corresponding guide wheel, and a pair of valves mounted on respective jacks for controlling the extension thereof. The valves are controlled by a pair of linkages which are connected to the steering wheel by a coupling mechanism in such a manner that the valves are simultaneously controlled in response to rotation of the steering wheel so that both guide wheels are laterally pivoted in the same angular direction.

Abstract: A servo device for steering gears for vehicles and ships is adapted to be coupled in a mechanical connection between said gear or the like and the steering rod or the like operated thereby. The device comprises a pair of opposed cylinder-and-piston units each having a working chamber, defined by the respective piston and adapted to be supplied pressurized fluid from a suitable source during control by valve means responsive to a movement of the output member of said gear and the resistance thereagainst of the steering rod operated thereby so as to amplify the power for overcoming said resistance by means of the pressure fluid in one of said pair of working chambers.