Abstract: An operation device for a friction clutch arranged in the drive train of a motor vehicle. The operation device includes a positioning servo arrangement with a pneumatic power cylinder arrangement. The pneumatic power cylinder arrangement acts on a clutch release sleeve arrangement. The positioning servo arrangement can be operated with a control valve that is connected to a pneumatic source depending on a command variable representing a desired position and an actual variable representing the axial position of the clutch release sleeve arrangement. The pneumatic power cylinder arrangement is arranged inside of the bell-shaped housing and the control valve is arranged outside of the bell-shaped housing or the bell-shaped housing is arranged at least partially inside of the bell-shaped housing, but is accessible from the outside and/or can be removed when the bell-shaped housing is attached to the combustion engine.

Abstract: A power brake apply system includes a master cylinder having a piston for generating fluid pressure within a braking circuit. A boost valve assembly is mounted adjacent the master cylinder and carries a slidable spool that selectively closes off a normal path of communication between a fluid reservoir and the boost chamber of the master cylinder in response to the manual actuation of the master cylinder's piston as effected through a pressurized braking circuit. After closure of communication between the reservoir and the boost chamber a power fluid supply is opened to the boost chamber to provide power assist in the actuation of the master cylinder's piston.

Abstract: A fluid pressure booster device includes a booster body, a control piston in the booster body for forward and rearward movements to define a boosting chamber between the control piston and a rear surface of a master piston of a master cylinder, a valve piston in the control piston for forward and rearward movements and communicating at its front face with the boosting chamber, a reaction piston in the control piston for forward and rearward movements and connected to an operating member, the reaction piston defining a reaction chamber between itself and a rear face of the valve piston, a stroke accumulator having an accumulation chamber connected to the reaction chamber, an inlet valve disposed between the control piston and the valve piston and interposed in a flow passage extending between the boosting chamber and a fluid pressure source, the inlet valve being closed when the valve piston is retracted and opening when the valve piston advances, and an outlet valve disposed between the control piston and the

Abstract: A modular brake actuator useful in automotove vehicles includes a mounting base adapted to fit into a complementary opening in and form part of the fire wall between the engine compartment and the driver's cockpit. On one side of the mounting base there are assembled brake operating components and on the other side there are assembled hydraulic components. This module can be easily installed during assembly of the vehicle.

Abstract: The present invention is an air control valve of an air clutch wherein an air valve assembly interlocking with an operated quantity of a clutch pedal is provided for controlling an air pressure supplied from an air pressure source to the air clutch. Control mechanism is provided for controlling a valve-open pressure of the air valve assembly by a hydraulic pressure from a master cylinder interlocking with the clutch pedal. The control mechanism includes first, second and third spring members of which spring constants gradually decreases in this order, and the valve-open pressure of the air valve body is adapted to be controlled while switching spring forces of the spring members in accordance with the operated quantity of the clutch pedal.

Abstract: The device comprises a tandem master cylinder, a booster high pressure fluid distributor, 2, a valve mechanism 4 to interconnect the master cylinder and the distributor selectively to a braking circuit. The high pressure circuit is connected to the pipeline 46 which controls the plungers 52, 56 acting on the ball valves 50, 51 respectively. In the event of failure of the high pressure circuit,the valves 50, 51 connect the pipeline 26 directly supplied by the master cylinder and the pipeline 5 which supplies a brake motor 8 for a wheel. The device may be utilized in an anti-skid circuit.

Abstract: Hydraulic assistance device for brake actuation comprising a body (10) having a bore (12) in which first and second piston mechanisms (34, 56) are slidably mounted, the first piston mechanism (34) being displaceable under the effect of the actuation of a third piston (16) mounted slideably in the bore (12), and the second piston mechanism (56) being displaceable by way of a hydrostatic connection formed in a presure chamber (60) defined between the first and the second piston mechanism (34, 56), there being associated with each piston mechanism (34, 56) a respective valve mechanism (52, 78) in a respective hydraulic circuit between a fluid source under pressure (54, 84) and a respective brake circuit (62,88), and a third chamber (30) defined in the bore (12) between the first piston mechanism (34) and the third piston (16), characterized in that the third chamber (30) is partially delimited by a fourth piston (92) which is displaceable under the effect of the pressure in the third chamber (30) as it meets a f

Abstract: A brake system wherein an input from an operator operates a first master cylinder (12) produces first and second hydraulic fluid pressures. Flexible conduit (22 and 24) carries the first and second hydraulic fluid pressures to an actuator (26) for a hydraulic power booster (28). A plunger (58) in the actuator (26) reacts either to the first hydraulic fluid pressure or the second hydraulic fluid pressure by moving to operate the hydraulic power booster (28). Operation of the hydraulic power booster (28) provides an input force to develop first and second operation fluid pressures in a second master cylinder (30) to effect a brake application.

Abstract: An electromagnetically operated mechanism produces an unstable first controlled pressure which, under a given condition, is saturated quickly to a degree slightly lower than a target value determined in accordance with an information signal issued from a brake pedal force detecting device. A servo-motor type actuator produces a stable second controlled pressure which, under a given condition, is saturated slowly to the target value. A control mechanism applies only the first controlled pressure to a work chamber of a pneumatic brake booster when the first controlled pressure is higher than the second controlled pressure, and applies only the second controlled pressure to the work chamber after the second controlled pressure becomes higher than the first controlled pressure.

Abstract: A floating plate is provided in a cylinder chamber and slides freely like a piston. A first group of laminated, ring-shaped, thin-plate piezoelectric elements is provided between a fixed support member provided on part of a wall portion of this cylinder chamber and the floating plate. A second group of laminated, cylindrical, thin-plate piezoelectric elements is provided in the center of the first group and a working member is provided on the free end of the second group of elements that is not attached to the floating plate. A hydraulic chamber is formed in the cylinder chamber on the side of the floating plate opposite to the side on which the first and second groups of elements are provided, and the pressure in this hydraulic chamber pushes the floating plate in the direction of the fixed support member.

Abstract: The hydraulic assistance device incorporates a casing (10) enclosing first and second sliding components (18, 20) arranged in line, the first component (18) being capable of being displaced under the effect of the displacement of a pushrod (34) and the second component being capable of being displaced through the intermediary of a hydrostatic connection, and associated with each component (18, 20) is a valve mechanism (36, 46) in a respective hydraulic circuit between a source of fluid under pressure and a respective braking circuit (I, II), characterized in that the first and second components (18, 20) each constitute a piston sliding in a bore (14) in the casing (10) and each encloses a valve assembly (26, 40; 36, 46) each controlled by a plunger (30, 44), the plunger (30) of the first valve assembly (26, 36) being actuated by the pushrod (34), and the plunger (44) of the second valve assembly (40, 46) being actuated by the hydrostatic connection between the two pistons (18, 20).

Abstract: In a brake valve of the type in which a given ratio is maintained between a master pressure developed by a brake pedal and an actual brake pressure, an arrangement is provided for continuous, rather than stepwise, adjustment of this ratio. The brake valve includes a control piston which is subjected to the master pressure and which, by the displacement thereof, opens and closes connecting channels between an accumulator containing a primary pressure fluid and a brake, as well as between the brake and a fluid collecting tank. The control piston and a measurement piston apply counter forces to the arms of a balance beam whose lever ratio determines the degree of feedback of the instantaneous brake pressure to the control piston. A stop is provided in the path of the axis of the control piston, which limits the stroke of the piston, to prevent the overloading of the balance beam during abnormally high braking pressures such as occur, for instance, during panic braking.

Abstract: Hydraulic assistance device, comprising a body (10) comprising a bore (12) in which a first piston mechanism and a second piston mechanism (18, 20) are slideably mounted, the first piston mechanism (18) being movable under the effect of the actuation of a third piston (16) slidably mounted in the body (10), and the second piston mechanism (20) being movable by the intermediary of a hydrostatic connection formed in a pressure chamber (22) defined between the first and the second piston mechanism (18, 20), a respective valve mechanism (60, 100) being associated with each piston mechanism (18, 20) in a respective hydraulic circuit between a source of fluid under pressure (52, 96) and a respective braking circuit (74, 110); and a third chamber (36) defined in the bore (12) between the first piston mechanism (18) and the third piston (16), the third chamber (36) being connected to a low pressure reservoir (25) through a passage in which a valve mechanism (42 ) is mounted, characterized in that the device incorpora

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 servo amplification system is created particularly for heavy construction equipment, but has a general utility that is much broader. The system utilizes a hydraulic analog system with a separate subsystem for each dimension of motion. The operator moves the operative element, such as the backhoe bucket, of the analog replica which ordinarily would be situated in the cab of the backhoe or other piece of equipment. A small hydraulic cylinder operative in response to movement at each articulated connection of the backhoe operates a pilot valve which controls a pilot piston mechanically linked to the drive valve of the drive cylinder of the corresponding articulation in the actual backhoe. A feedback system comprising a mechanical link from the actual drive piston to a feedback cylinder and piston delivers hydraulic fluid back to the inlets of the pilot valve in such a way as to cancel the pilot orders from the initial control cylinder.

Abstract: A closed center four-way poppet actuator control device is incorporated into a pneumatic actuation system for controlling the movement of flight surfaces. The closed center four-way poppet actuator control device has a housing, a pair of two-way poppet valves in the housing, a rocker arm assembly mounted on the housing and connected to the pair of two-way poppet valves, and a diaphragm assembly also mounted in the housing and in contact with the two-way valves. A torque motor-driver assembly connected to the diaphragm assembly actuates the two-way valves as determined by control signals. The rocker arm causes the two-way valves to function oppositely each other: one allows high pressure gas to be input to a lobe motor actuator while the other allows gas to be output from the lobe motor actuator. Each two-way valve has a cylindrical poppet valve for inletting the gas to the actuator and a disk poppet valve for outputting the gas from the actuator to a vent.

Abstract: A hydraulic brake booster includes a booster piston axially slidable in a bore of a housing and delimiting therein a boosting compartment, and a brake pedal responsive operating element which partially extends into the boosting compartment to act as a plunger therein. A control valve has a valve body which is stationary relative to the housing and a valve member which is slidably received in the valve body and controls communication of a pressure chamber with sources of control fluid at reference pressure and at control pressure, the pressure in the boosting compartment being proportionate to the pressure in the pressure chamber.

Abstract: A valve body is disclosed located in the hydraulic system of a machine which valve serves to direct hydraulic fluid under pressure to hydraulic components or divert the fluid to a system reservoir to prevent component operation. A check valve in the valve body is opened or closed by control means with the check valve indirectly determining the position of a pressure responsive spool for either normal fluid passage to hydraulic components or fluid diversion back to a reservoir. Remote actuation of the control means is by a hand operated air, lockable pump to enable an authorized equipment operator to remotely actuate said control means to effect locking or unlocking of the hydraulic system by positioning the check valve. A modified check valve control dispenses with the air pump and utilizes a lock plunger to bias the check valve to a closed position for normal hydraulic system operation or, conversely, to open the check valve to divert pressurized fluid back to a system reservoir.

Abstract: A pedal-operated booster incorporates a valve mechanism for controlling pressurization of a boost chamber. The valve mechanism comprises a pedal-operated piston and a pressure-responsive valve spool which is coupled to the piston for limited relative movement in a longitudinal direction within a working chamber in the piston. The spool is movable with the piston in an initial brake-applying direction in which the spool is operative to isolate the boost chamber from an exhaust port and the piston is operative to place an inlet port in communication with the working chamber. This causes the spool to move relatively away from the piston in response to pressure fluid in the working chamber which is admitted to the boost chamber.

Abstract: A toggle assembly for vehicles or cars comprising a relay cylinder mounted on an end plate including a booster cylinder and an output cylinder, a control chamber arranged in coaxial relation to the relay cylinder, a control valve for controlling a gas by a hydraulic pressure of a master cylinder, said valve being arranged in operable association with the control chamber, and a booster piston disposed in the booster cylinder and in operable association with the controlled gas, wherein said end plate is provided with a shell for said booster cylinder as an integral piece, said shell is integrally provided with a first compressed air passage having its one end being open in the back chamber of the booster cylinder for the booster piston and its other end passing through said end plate and being open at the end of a relay valve body, and a second compressed air passage is provided to extend from a casing for said control chamber, said second passage having its one end in communication with the other open end of s

Abstract: Hydraulic apparatus (7), for use where a hydraulic actuator (42) is powered by a first hydraulic supply (40) or selectively and alternatively by a second hydraulic supply (41) independent of the first, which, when a fault occurs, will establish whether the actuator or the first hydraulic supply is at fault, and if it is the first hydraulic supply will isolate that supply and select the second hydraulic supply, but if it is the actuator will ensure that both supplies are isolated. Moreover, the apparatus will establish whether the actuator fault is tolerable and if it is, will select the second supply. By the arrangement described a second hydraulic supply is selected when the first fails, but if the actuator is at fault the second supply will only be selected if that fault is tolerable; if the second supply were to be selected if the actuator was intolerably faulty, failure of the second supply would follow in rapid succession.

Abstract: A hydraulic circuit (32), for example, remotely controls a work element (14) and contains first apparatus (34), such as a master cylinder (42), which passes a fluid pressure signal through a fluid pathway (38, 40) in response to an input signal. Second apparatus (36), such as a slave cylinder (44), correspondingly delivers an output signal for controlling the work element (14). Temperature variation can cause fluid volume changes which disrupt synchronized operation of the master and slave cylinders (42, 44). Third apparatus (74) positions the fluid pathways (38, 40) in fluid communication with a tank (28) in the absence of the fluid signal. If the signal passes through one pathway (38, 40), that pathway (38, 40) is automatically blocked from communication with the tank (28). Thus, when the fluid signal is absent from the fluid pathways (38, 40), volume compensation occurs because of dilution of the fluid in the circuit (32) with the tank fluid.

Abstract: An hydraulic booster in which a control chamber is defined between an input piston and a second piston relative to which the input piston is movable, and recuperation valve for controlling communication between the control chamber and a reservoir is located in the control chamber. The recuperation valve closes upon relative movement of the input piston towards the second piston, further movement of the input piston in the same direction causing pressurization of fluid trapped in the control chamber.

Abstract: A brake force servo-device, especially for motor vehicles, with a control piston, selectively actuatable preferably by a brake pedal, which cooperates with a connecting valve connected with a pressure medium source and which is operable to displace a flow medium out of its cylinder space for the actuation of the connecting valve; a working piston is thereby actuated by the pressure controlled by the connecting valve, whereby the control piston is constructed as one-piece control piston having an annular step and is sealed off, on the one hand, within the area of its entry into the brake force servo-housing and, on the other, in proximity of its end face which projects into a working pressure space; the control piston thereby abuts at the working piston present in the working pressure space while the connecting valve is actuated by the flow medium displaced by the annular-shaped step of the control piston out of the annular space which is formed between its two bearing places.

Abstract: The invention relates to a hydraulic control, particularly for automobile brake systems having two separate independent brake circuits, in which a master cylinder comprises a first chamber in which pressure is controlled by the driving-in of a master piston under the action of a brake pedal, the first chamber forms a part of a first hydraulic closed system comprising a first brake circuit, the master cylinder also has a second pressure chamber forming part of a second closed system comprising a second brake circuit. The second chamber is adapted to be fed by a source of fluid pressure and the master cylinder is provided with a plunger the opposite faces of which are respectively subjected to the pressures of the two closed systems. The master piston is disposed in the first chamber coaxially with the plunger in such a manner as to permit mechanical intervention in the event of hydraulic failure in the first closed system.

Abstract: A hydraulic brake booster includes a housing 12 with a first chamber 40 and a second chamber 42. An input member 54 extends into the first chamber 40 and is exposed to the second chamber 42. The input member is movable within the first chamber 40 to increase fluid pressure within the second chamber 42 and this fluid pressure operates a control valve 90 to communicate fluid pressure to the first chamber 40. The fluid pressure in the first chamber 40 acts against the input to bias the same toward the second chamber 42. An output member 70 is movable in response to the fluid pressure within the second pressure chamber 42 to actuate braking.

Abstract: The charging valve comprises a pressure port connected with a pressurized fluid source, a first user port which is connectible to a first user component, a second user port which is connectible to an accumulator and to a second user component of the closed center type and a valve device which is switchable dependent upon the pressure existing in the accumulator. The valve device, below a predetermined pressure in the accumulator, connects the pressure via a throttle with the second user port and, above a predetermined pressure in the accumulator, connects the pressure with the first user port. The valve device includes a closing valve which is controlled by a control pressure and the closing valve closes the connection of the pressure port with the first user port, if the pressure in the accumulator is below the predetermined pressure. Further, the closing valve can only be closed by the control pressure if the center of the second user component is open.

Abstract: A power brake unit for automotive vehicles comprising a brake valve through which pressure-transmitting fluid is metered from a fluid source into a booster chamber to actuate a booster piston. A hydraulic transmission ratio provided by an input piston connected to a brake pedal and an operating piston connected to the brake valve reduces the pedal actuating travel when the fluid source is intact and is ineffective in the event of a failure of the fluid source. Only non-boosted forces are transmitted through the hydraulic transmission ratio. Should the fluid source fail, the hydraulic transmission ratio is rendered inoperative in a simple and safe manner.

Abstract: A hydraulic power booster system in which a hydraulic power brake booster has hydraulic ratio changing mechanisms. The ratio is established by trapping hydraulic fluid in a chamber with an input piston having a larger effective area than an output piston forming movable chamber walls. A ratio piston or sleeve exposed to booster power pressure and the trapped pressure is moved upon power runout, causing the booster ratio to change as the ratio of these pressures change, providing a smooth transition from a high ratio toward a 1:1 ratio as the booster shifts to manual operation from hydraulic power operation. These are three booster modifications shown.

Abstract: A hydraulic power booster system in which a hydraulic power brake booster has a hydraulic ratio changing mechanism. The ratio is established by trapping hydraulic fluid in a chamber with an input piston having a larger effective area than an output piston forming movable chamber walls. A ratio piston or sleeve exposed to booster power pressure and the trapped pressure is moved upon power runout, causing the booster ratio to change as the ratio of these pressures change, providing a smooth transition from a high ratio toward a 1:1 ratio as the booster shifts to manual operation from hydraulic power operation. A valve which operates to trap pressure in the chamber upon booster actuation also provides a vent path from the chamber when the booster is fully released so that any air in the chamber may be bled out.

Abstract: A hydraulic power booster system in which a hydraulic power brake booster has hydraulic ratio changing mechanisms. The ratio is established by trapping hydraulic fluid in a chamber with an input piston having a larger effective area than an output piston forming movable chamber walls. A ratio piston or sleeve exposed to booster power pressure and the trapped pressure is moved upon power runout, causing the booster ratio to change as the ratio of these pressures changes, providing a smooth transition from a high ratio toward a 1:1 ratio as the booster shifts to manual operation from hydraulic power operation. A trapped hydraulic fluid link is established between the input piston and the booster output member for manual operation. These are two booster modifications shown.

Abstract: A self contained hydraulic valve system, for controlling the flow of a normally gaseous fluid such as, for example, anhydrous ammonia, includes a hydraulic valve connected to a pressurized vessel holding said normally gaseous fluid, a master cylinder hydraulically connected to said valve and controlling the operation thereof, and a hydraulic connection between the hydraulic valve and master cylinder. In operation, when the manual lever of the master cylinder is depressed, the hydraulic fluid within the self-contained system is pressurized thereby forcing the hydraulic valve open.

Abstract: A self-advancing mine roof support is provided, in addition to the normal manually operable control valve means for controlling raising and lowering of the roof-engaging structure of the support and operation of the advancing means, with an automatic sequence control valve means operable in response to a control signal from a position removed from the support, for example from an adjacent support, and an isolating valve means arranged so that control of the various operations can be effected either by means of the manually operable means or from the safety of a location spaced away from the support being controlled by means of the automatic valve means each independently of the other.

Abstract: A servo-assisted hydrodynamic braking system of the type in which brake pedal pressure is used to control a modulating valve which restricts an output line of a pump thereby increasing the pressure in the output line which is connected to the master cylinder of the braking system in such a way as to apply this increased pressure as a servo-assisting pressure, in which the master cylinder and modulating valve are made as a composite assembly and the pressure within the master cylinder part is used to control the modulating valve so that no direct mechanical interconnection between the brake pedal and the modulating valve is needed.

Abstract: Servo-assisted hydraulic braking system of the type in which brake pedal pressure is reinforced by a pressure dependent thereon and fed to a master cylinder driving piston by a distributor device which is fed with fluid under pressure from a pressure source and control pressure from control chambers defined by plungers within the master cylinder itself, which plungers are displaced directly or indirectly by the displacement of the driving piston of the master cylinder. The distributor plungers are balanced so that for a given brake pedal pressure they feed through a certain reinforcing pressure and then close off the driving piston chamber from the pressure source, locking in the reinforcing pressure so far applied, so that variations in the pressure generated by the pressure generating device are not fed back to the brake pedal via the driving piston of the master cylinder.

Abstract: A device for infinitely controlling the position of a controlled member along its axis of movement. The device includes hydraulic actuators coaxially secured to the controlled member and a mechanically and/or manually actuated cylinder is fluidly connected to the hydraulic actuator so that by actuation of the cylinder, both the speed and the position of the controlled member along its axis of movement can be carefully controlled.

Abstract: A brake force booster installation with a mechanical, pneumatic or hydraulic actuating mechanism acting on a servo- and adjusting-unit, which in turn acts on the master cylinder, with filling devices and with control- and shifting-devices; the filling devices and the actuating mechanism are thereby actuated by movement of the brake pedal lever pivotally connected at two connecting points to the piston rods of an actuating piston and of a filling piston while the filling devices and the actuating devices are so arranged separated from one another and are so connected with the control and shifting devices that the brake pedal lever during its idle path is actuated with one lever ratio by holding fast one piston rod and thereupon the working effect is realized by automatically shifting to a different translation ratio.

Abstract: A control mechanism for regulating operation of a rotatable winch drum through a power train including a brake which is normally engaged by hydraulic pressure to secure the winch drum against rotation and a normally disengaged clutch which is selectively engaged by hydraulic pressure for driving the winch drum in a reeling-in mode, the control mechanism including a control lever which is movable for selectively communicating hydraulic fluid to the brake and clutch, first and second biasing means being associated with the control lever to provide for adjustment of the lever at different rates of modulation.

Abstract: A hydraulic boosting apparatus in a braking system, which apparatus has an accumulator which provides an oil pressure accumulated in a high pressure circuit, the oil pressure being supplementarily used in addition to an oil pressure from the usual hydraulic circuit for a braking operation. A booster cylinder has a booster piston, a free spool and an operating spool which are arranged coaxially with each other. There is provided a pressure chamber between the booster piston and the free spool, which chamber communicates with a first working chamber defined in and serving to close an on-off valve which is, in turn, in communication with the accumulator. There is also provided a closed chamber between the free spool and the operating spool, which chamber communicates with a second working chamber defined in and serving to open the on-off valve.

Abstract: A motor vehicle fluid power circuit is provided with a constant displacement pump, a control valve, an open-center steering valve, and a hydraulic ratio type brake booster. The control valve includes a control spool which controls fluid flow between the pump and the brake booster and between the pump and the steering valve. A control spool modifying means modifies the operation of the control spool during initial actuation of the brake pedal to produce a large increase in brake booster pressure.

Abstract: A hydraulic booster is disclosed which includes a piston which is actuated by fluid pressure communicated into the booster working chamber from an accumulator by a spool valve. An operator actuated input rod generates fluid pressure in a control chamber when the booster is actuated. The pressure generated in the control chamber shifts the spool valve to a position admitting fluid pressure in the working chamber. An exhaust passage including a relief valve communicates said accumulator chamber with said control chamber. The accumulator includes a piston adapted to bias the relief valve into its open position when the fluid pressure level in the accumulator chamber is below a predetermined value.

Abstract: The positioning of the piston rod of a double acting hydraulic cylinder is accurately controlled by means of applying hydraulic pressure, created by the controlled displacement of a fluid independent from the primary fluid system, against the piston of a servo-cylinder which controls the servo-valve for the double acting cylinder. As the piston rod of the double acting cylinder moves, the pressure on the servo-cylinder is relieved and the servo-cylinder is returned to a balanced condition, restoring the neutral position of the servo-valve. In another embodiment the application of pressure to a fluid system independent from the primary fluid system is sensed by an electro-hydraulic transducer and a proportional electric signal is produced for controlling the electro-hydraulic servo-valve of the double acting cylinder. As the piston rod of the double acting cylinder moves, fluid is displaced, relieving the sensed pressure and returning the servo-valve to a neutral position at a new setting of the piston rod.

Abstract: A motor vehicle fluid power circuit is provided with a constant displacement pump, a control valve, an open center steering valve, a hydraulic ratio type brake booster, and a ratio override valve. The control valve includes a shuttle piston which controls fluid flow between the pump and the brake booster, between the pump and the steering valve, and between the brake booster working chamber and the downstream side of the steering valve. The brake booster includes a trapped volume chamber in which a larger area input rod moves to provide greater movement of an output rod and power piston assembly.

Abstract: An arrangement for achieving effective steering and control of any type of vehicle employing hydraulic follow-up, as, for example, the rudder of a vessel, where the components thereof are so related that the rudder will automatically follow the true position of the steering mechanism.

Abstract: A hydraulic booster is disclosed which includes a control valve comprising a sleeve-shaped spool and a control piston slidably mounted at one end of said spool. The control piston projects into a control chamber filled with hydraulic fluid and in which are movable an operator-operated input member and an output member connected to a boost piston slidably mounted in a working chamber. The pressure generated in the control chamber shifts the control piston and the spool to a position admitting fluid pressure from a pump into the working chamber. The ratio of the effective areas of the control valve respectively submitted to the control pressure and to the pressure prevailing in the working chamber is about two.