Abstract: A reservoir for holding pre-fill hydraulic fluid is connected at its bottom to the power input side of a hydraulic motor. A stand pipe within the reservoir is connected to a hydraulic fluid drain outlet for expulsion of excess volume hydraulic fluid. Compressed air is introduced to the reservoir at a level above the top of the stand pipe. Valving in the compressed air line is operable to three states: opened between the compressed air source and the reservoir; opened between the reservoir and the atmosphere and closed. A valve connected in the drain outlet may be opened or closed. A check valve between the reservoir and the hydraulic motor is held opened by pilot operation during return of the hydraulic fluid to the reservoir and checked closed during high pressure input to the hydraulic motor.

Abstract: In a vehicle brake system including a pneumatic force multiplier apparatus in which a power piston moves by virtue of a pressure difference between atmospheric and negative pressure, a manual brake switch is provided to apply braking force without need for depressing the brake pedal. A controller includes a deceleration calculating circuit reading vehicle speed for every specified number of seconds and calculating the amount of deceleration. The deceleration is compared with a predetermined value and braking force is increased, maintained, or decreased depending on whether the vehicle is running on a downwardly sloping, level, or unwardly sloping road.

Abstract: The actuator (12) comprises three main parts, an outer casing (20), a movable piston (28) and a fixed piston (36). A stepped outer portion (50, 52, 54) of the movable piston (28) cooperates with a stepped cavity (40, 42, 44) in the casing (20) to define a plurality of concentric, variable diameter fluid chambers (1, 2, 3) bounded at their ends by radial surfaces on the movable piston (20) and within the casing cavity. The movable piston (20) and the fixed piston (36) define a plurality of axially spaced apart variable diameter fluid chambers (1', 2', 3') which are bound on their ends by radial surfaces on the fixed piston (36) and radial surfaces within the cavity formed in the movable piston (20). One set of the chambers (1, 2, 3) is connected to supply pressure (P.sub.S) and the second set of chambers (1', 2', 3') is connected to return pressure (P.sub.R). Seal receiving grooves are formed in outer surface portions of the fixed and movable pistons (28, 36). Seal rings (S.sub.

Abstract: Two pistons (5, 8) are mounted in the same casing (1) so as to slide in a sealed manner, the two pistons (5, 8) being firmly fixed to one another and having corresponding actuating chambers (21, 22; 23, 24) which are separated from one another and are supplied sequentially by two distribution valves (A, B) which are situated in the casing (1) and are actuated by the input shaft (14). The second piston (8) is formed by an extension (7) of the first piston (5) and its corresponding actuating chambers (22, 24) are formed in the piston structure (5, 8) and by a housing (4) in the casing (1), respectively, the housing (4) being coaxial with the main housing (3) for the first piston (5). The two valves (A, B) are advantageously of the type having a star-shaped rotor (30, 40).

Abstract: A pressure-fluid-operable vehicle brake system is proposed, which is fed by an auxiliary energy supply system (3) and which comprises a master cylinder device (1), in which a booster piston (40) adapted to be acted upon by the auxiliary energy is slidable in a pressure fluid chamber (26). When the auxiliary energy supply system (3) is intact, the booster piston (40) comprises an effective area for the pressurization of a wheel brake cylinder which is larger than an effective area which results upon failure of the auxiliary energy supply system. Upon failure of the auxiliary energy supply system (3), the necessary deacceleration is achieved because of a smaller effective area at the booster piston (40) and at a greater displacement travel of the booster piston (40) and with less pedal force (F).

Abstract: A two-speed, pilot-operated selector valve which directs hydraulic fluid to two motor elements with a common output shaft to obtain a high-torque, low-speed mode, or to one motor element, while recirculating the second element in a loop, to obtain a low-torque, high-speed mode. The spool has a built-in logic mechanism which, while shifting from one position to the other, prevents any momentary condition where a motor discharge port is blocked or a fluid path exists that bypasses both motor elements.

Abstract: Hydraulic safety device for the mechanism for closing up the rolls of a rolling mill, comprising an hydraulic safety valve (20) which is accommodated directly inside the jack (1) for closing up the mill rolls and which automatically reduces the pressure of the fluid in the control chamber (12) as soon as the stroke of the body (11) of the jack reaches a predetermined limiting position.

Abstract: A vacuum brake booster includes a pair of diaphragms which move in opposite directions during a brake application. One of the diaphragms is connected to a valve assembly to generate a first force assisting braking while the other diaphragm generates fluid pressure in an output chamber formed substantially by the valve assembly. The fluid pressure in the output chamber generates a second force assisting braking.

Abstract: A hydraulic actuator assembly for a push-type die closing unit of an injection molding machine which has a central, internally bypassable power piston, lateral cylinders for rapid opening travel and a rearward stationary plunger for rapid closing travel, the lateral travel cylinders and the pressure spaces of the power cylinder creating a differential effect under which a small external flow volume of pressurized fluid is required from the pump to produce rapid opening and closing travel while a much larger internal flow volume passes through a flow connection between the cylinders. A program-controlled proportional-response throttle valve in this flow connection gives an accurate and steady control over the travel speeds, especially during deceleration. The throttle valve also makes it possible to obtain a forcible initial die opening movement.

Abstract: A brake system for an off-highway vehicle which includes a fluid pressure actuated multi-disc brake and a fluid pressure control system. Engagement of the multi-disc brake is effected by a fluid operated piston having multiple effective pressure areas. Fluid pressure applied to a certain of the effective pressure areas urges the piston in a brake applying direction; fluid pressure applied to the other of the pressure areas urges the piston in a brake releasing direction. The fluid pressure control system controls the communication of pressurized fluid to the effective pressure areas to provide both the brake applying and brake releasing functions. Redundant fluid pressure circuits supply pressurized fluid to the brake applying effective pressure areas. In the event of failure, the control system is operative to interrupt fluid flow to the failed circuit.

Abstract: A combined brake cylinder/air reservoir device in which a relatively small, tubular-shaped piston in a positioning chamber is connected to a larger power piston having an application chamber on one side and a release chamber on the other side in which air is stored in place of separate reservoirs. A replaceable cylinder liner is provided to receive different-sized power pistons. During a brake application, the power piston enters the cylinder liner and is displaced from the liner during brake release to provide free air flow between the application and release chambers and thereby facilitate piston return movement by means of a return spring. A dynamic pressure seal between the application chamber and positioning chamber engages the outer periphery of the tubular-shaped small piston, while a smaller diameter dynamic pressure seal between the release chamber and atmosphere engages the inner periphery of the tubular-shaped small piston.

Abstract: An extracting screw apparatus comprises a hydraulic control which operates during starting of the extracting screw after a period of nonuse. The hydraulic control comprises a double-acting hydraulic actuator having a piston rod connected to an intermittent drive such as an overrunning clutch for rotating a driving shaft for the extracting screw about its axis. The intermittent drive converts linear reciprocating movement transmitted by the hydraulic actuator into intermittent angular movement. A hydraulic motor alone insures rotation of the extracting screw about its axis after starting and also insures the sweep movement of the extracting screw about a vertical axis. A hydraulic control circuit connected between a line running from a pump to the hydraulic motor for cutting off hydraulic fluid to the double-acting hydraulic actuator after normal operating torque is reached.

Abstract: An hydraulic jack having more than two chambers is disclosed and is intended for use in a system of jacks, the displacement of which is to be synchronized. Each jack has a cylindrical center cavity in which a piston with a cylindrical cross section reciprocates, an annular cavity in which a piston with an annular cross-section reciprocates, and a rod for transmitting thrust connected to both pistons. In order to provide the jack with a minimum longitudinal dimension and with maximum rigidity, the two cavities are concentric and are separated by a stationary intermediate wall. The two pistons are connected to the rod for the transmission of thrust.

Abstract: A rotating servomotor apparatus for use in rotating guide vanes in a hydraulic machine, wherein for the purpose of suppressing occurrence of flow-induced vibrations, there is provided a bearing to support wicket gates, a rotating servomotor which includes a movable spindle projecting in the axial direction and which has a plurality of movable partition members, a cylinder having a plurality of stationary partition members disposed around the spindle, and a plurality of compartments partitioned between the movable partition members and the stationary partition members; and a first distributing valve connected to one side of plural compartments within the cylinder of the rotating servomotor means, a second distributing valve connected to the other side of plural compartments within the cylinder of the rotating servomotor means, wherein the respective distributing valves have valve piston members sized and arrangeable with respect to fluid inlets and outlets to define a neutral position in which fluid is supplie

Abstract: A tandem diaphragm brake booster includes a housing, first and second diaphragms disposed in said housing, a partition wall disposed between said first and second diaphragms within said housing for defining four pressure chambers. The housing is composed of a cup-shaped shell section having a broad cylindrical outer wall and a flange shaped rear shell section. A bead of the first diaphragm is situated between the inner surface of the front sell section and a securing member of the partition wall for defining the first and second chambers. The second diaphragm has inner and outer beads and through-holes at its periphery. The inner bead is compressed between the peripheral edge of the partition wall and the inner surface of the rear shell section and the outer bead is air-tightly secured between both peripheral edges of the front shell section and rear shell section.

Abstract: A jacking apparatus and method for effecting movement of loads. At least two double-acting hydraulic cylinders including a first and a second cylinder arranged in tandem provide increased force for a power stroke of the apparatus. Hydraulic fluid pressure is provided at a predetermined flow rate to the group of hydraulic cylinders. Substantially all of the predetermined flow rate of hydraulic fluid is routed to the first hydraulic cylinder to provide increased speed for a repositioning stroke of the apparatus.

Abstract: A brake apparatus 10 having a master cylinder 16 with a flange 24 connected to a first shell 56 of a booster 18 and a stationary firewall 71 of a vehicle. A first wall 70 located between the flange 24 and first shell is connected to a piston 38 in the master cylinder 14. A second wall 144 located between the first shell 56, flange 24 and a second shell 121 is linked to the first wall 70 by a plurality of bolts 180 that pass through the flange 24. A valve 102 in response to an input controls the development of a pressure differential across the first and second walls 70 and 144. This pressure differential creates a force such that the first wall 70 pushes piston 38 while the second wall 144 pulls the first wall 70 to pressurize fluid in the master cylinder 16. Since the flange 24 fixes the master cylinder 16 to a stationary firewall 71, measurable axial deflection is eliminated and the entire input is used to operate valve 102 and effect a brake application.

Abstract: An apparatus for closing a mold in an injection-molding operation has a double-acting main piston that is connected to a mold-carrying plate and that move axially in a main cylinder. A rapid-action piston extends into a small-diameter bore in the main piston, and the rear cylinder wall is formed with a large-diameter fill passage connected directly to a sump. A positioning cylinder is fixed on the main cylinder and contains a positioning piston axially fixed on the rapid-action piston and having in the positioning cylinder a rearwardly directed face larger than the face of the rapid-action piston and forming with the positioning cylinder a pressurizable positioning chamber. A passage extends axially through the rapid-action piston from its cylinder to the positioning chamber.

Abstract: A hydraulic adjustment apparatus as is for instance used to adjust a roller of a rolling mill has a cylinder forming a first cylinder chamber and having a first cylinder surface directed backwardly in a predetermined direction in the first chamber. A first piston is displaceable forwardly and backwardly in the direction in the first chamber relative to the cylinder and has in this chamber a forwardly directed first piston face of a predetermined first piston area. The first piston is formed with at least one second chamber receiving a forwardly and backwardly displaceable second piston having a forwardly directed end engageable with the first chamber surface. This second piston in turn has a second piston face of a predetermined second piston area substantially smaller than the first piston area and directed backwardly in the second chamber.

Abstract: A hydraulic operating apparatus including an actuating cylinder having a piston arranged therein and moved by a fluid under high pressure further includes a control valve having only one metallic seal whether the piston is at its upper or lower positions. The control valve is operative to apply the fluid under high pressure to a pressure receiving surface of the piston on the opposite side of a piston rod to move the piston in a direction in which the piston rod extends from the piston and to discharge the fluid existent on the opposite side of the piston rod from the actuating cylinder to move the piston in a direction opposite the direction in which the piston rod extends from the piston.

Abstract: A hydro-pneumatic operating device for motor vehicle clutches permits shifting into second or higher gears without operation of the clutch pedal, by manipulation of an electric switch that actuates an electro-pneumatic valve. A cylinder block 31 is provided that houses a hydraulic working cylinder having a hydraulic piston of a hydro-pneumatic piston, and a pneumatic servo-valve unit whose path control is actuated by an external operating element which cooperates with a pneumatic servo-piston (14) of the hydro-pneumatic piston (20). On an end face of the pneumatic servo-piston (14) opposite a pneumatic servo-chamber (11) there is a supporting surface 19 whose countersurface 118 is formed on the pneumatic servo-piston (20a) of the hydro-pneumatic piston 20. The other side of pneumatic servo-piston 20a confines a blow-off chamber 22. A cylinder section 13 of a pneumatic working chamber 15 enclosed by the hydraulic pneumatic piston 20 and the pneumatic servo-piston 14 has a connection 66 for pressure medium.

Abstract: A hydraulic actuator assembly for use in the die closing unit of an injection molding machine, the actuator assembly having a large power cylinder and a smaller travel cylinder with a large power piston and a small travel piston on a common piston rod, and bypass channels in the power piston which are openable and closable by means of an annular valve plunger moving on a guide sleeve on the piston rod. The valve plunger and the guide sleeve have three stepped cooperating sliding diameters forming bypass opening and closing plunger pressure spaces. Hydraulic pressure is supplied to the two pressure spaces through bores in the piston rod.

Abstract: Hydraulic actuating apparatus with digital input comprising a movable output member spring biased to a neutral position and capable of moving to one or other of two working positions under the effect of opposing hydraulic means, themselves controlled by binary-type control members;To create two additional working positions for the movable output member (10), the invention provides for each of the driving means to be composed of two active areas (s.sub.1, s'.sub.1 ; s.sub.2, s'.sub.2) acting successively on the output member (10), and for the putting of the first area under pressure to be caused by one of the control members (EV.sub.1, EV.sub.2) while that of the other area is caused by the other control member provided that the output member has already completed a first displacement step in the required direction;Particular application to the control of double-acting hydraulic actuators with two rates of displacement in each direction.

Abstract: A linear fluid actuator having two pistons and two cylinder chambers in tandem to provide redundancy when supplied from independent pressure sources. The actuator is balanced in that the actuator output force is equal in extend or retract positions. The two cylinder chambers are made from separate housings to prevent crack propagation between the chambers and dual piston rod construction is provided to enhance redundancy.

Abstract: A loader vehicle includes a loading implement movable to a dump and a rack-back position by means of actuation of cylinders. The movement of the cylinders is provided by fluid control valves in turn operated by actuator means which provide for both a slow dump and a fast movement of the implement.

Abstract: A mold closing device of an injection molding machine is disclosed which is reliable in operation and simple in structure. Both the opening and closing of the valve for hydraulic oil passage can be attained in the mold closing device of the invention in which two valve controlling oil chambers are formed in the boundary between the valve member and a quick shifting ram. One of the above oil chambers is connected to a forward cylinder and the other, to a return cylinder, thereby attaining the opening and closing of valve by hydraulic pressure in synchronism with the movement of a mold closing piston which is attached to the quick shifting ram.

Abstract: A fluid circuit connects a first pump to a first motor and has a control valve for controlling fluid flow to the first motor. The control valve is movable between a first position at which the first pump is blocked from communication with the first motor, a second position at which fluid flow to the motor is controllably modulated and a third position at which substantially the full output of the first pump is directed to the first motor. A valve device connects a second pump to the fluid circuit and is movable between a first position at which the second pump is in communication with a tank and a second position at which the output of the second pump is combined with the output of the first pump. The valve device is moved to the second position in response to the control valve being moved from said second position toward said third position.

Abstract: A hydraulic drive for the die closing unit of an injection molding machine in which at least one power cylinder and power piston with a coaxially attached auxiliary cylinder opens and closes the molding die by executing the opening and closing travel with a differential piston action in the power cylinder and/or with the auxiliary cylinder, while valve-closable bypass channels in the power piston are kept open. The closing of these channels switches the drive from an accelerated travel mode to a high-pressure die clamping mode.An annular valve plunger cooperates with a valve seat on the power piston to open and close the bypass channels, several alternatives of guiding and hydraulically moving the valve plunger being contemplated.