Abstract: A control block is made up of a plurality of directional valves which serve to actuate a plurality of hydraulic drives to which in some cases a different pressure is to be supplied. For this purpose two pressure-limiting valves adjustable to different pressures are provided, the valve adjustable to the lower pressure being connected to the last valve unit. This gives a simple construction and substantial freedom in the association of the drives.

Abstract: The steering system of some lightweight vehicles are electronically controlled and have a manually operated mechanical control as a backup. Such manual backup control would not be adequate for large earthmoving, construction and industrial type vehicles. The subject steering system includes an electrically controlled circuit actuated by rotation of a steering wheel for controlling a main pilot operated steering valve as the primary steering control. A hydraulic control circuit is also actuated by rotation of the steering wheel for controlling the same steering valve as a backup control when the electrically controlled circuit is not active. The hydraulic steering circuit is disabled when the electrically controlled circuit is activated. By using the same steering valve as an integral part of both circuits, the complexity and cost of the overall steering control system is reduced.

Abstract: On actuation, each pressure generator at each of a plurality of locations along a conduit develops a pressure rise in the conduit to energize a pressure sensitive device in fluid communication with the conduit. Each pressure generator includes a bulbous member which expels a quantity of fluid (air) into the conduit when depressed and a valve for segregating the volume defined by the bulbous member from the conduit except when the bulbous member is depressed to minimize dissipation by a nonactuated pressure generator of the pressure rise within the conduit and generated by another actuated pressure generator.

Abstract: Hydraulic assistance device, incorporating a casing (10) provided with a bore (12) in which first piston means (16, 18) is slideably mounted, the piston (16, 18) being able to move under the effect of the actuation of a brake pedal between a first position allowing communication between a first chamber (72) which is connected to a braking circuit (70) and a low pressure reservoir (40), and isolating this chamber (72) from a source of high pressure fluid (76), and a second position isolating the chamber (72) from the low pressure reservoir (40) and causing it to communicate with the high pressure source (76), the device also incorporating a second chamber (38) formed in the casing (10), the communication between the first chamber (72) and the reservoir (40) incorporating a second bore (52) in which a control piston (54) of second piston means (54, 60) is slideably mounted, incorporating a bore (56), the first piston having a bore in which a plunger (31) is slideably mounted, the plunger (31) joining the first

Abstract: An improved zone control apparatus having mode selectors which allow a user to select any one of a variety of operating modes for individual fluidically actuated flow control devices. The invention further provides for a smoke damper which upon automatic or manual activation causes all of the flow control devices to restrict flow of conditioned fluid through respective ducts or pipes so as to help minimize smoke contamination and the formation of a "chimney" effect. The invention further provides for the utilization of vibration type diaphragm pumps to create a source of pressure and vacuum, a pressure test device to quickly check the pressure in the apparatus, and a flow indicator for determining the location of leaks in the apparatus.

Abstract: A pull-type pneumatic booster comprises an elongated plunger received in a body for sliding movement along an axis thereof. A movable member is slidably received in the body and defines a low and a high pressure chamber therein. The high pressure chamber is controlled by a valve device to communicate with either of the low pressure chamber and a high pressure source in accordance with the movement of the plunger. One end portion of the plunger extends beyond the movable member into the low pressure chamber. The plunger has the other end portion of a tubular configuration. The front and rear end portions of the plunger are snugly fitted in and disposed in sliding contact with an inner surface of a tubular portion the movable member for guiding the movement of the plunger along the axis of the body. A load-transmitting means is received in the tubular rear end portion of the plunger for transmitting a reaction force applied to the output member to the input member via the plunger.

Abstract: An actuator system is disclosed which modulates a linear output shaft associated with a working control valve or the like in response to a control signal input. The system includes a feedback control link, a pneumatic positioner, a pneumatically controlled hydraulic valving system and a hydraulic cylinder and piston assembly controlled by the hydraulic valving system. The hydraulic valving system includes a three-position, four-way valve actuated by pneumatic binary output signals from a signal conditioner which is in turn controlled by the positioner. Hydraulic flow to the three-position, four-way valve may also be controlled from the signal conditioner in response to positioner output for most effective actuation of the hydraulic cylinder and piston assembly. Failure modes are also disclosed with the present system. The resulting system exhibits extremely rapid response times and high accuracy with dynamic stability.

Abstract: For use with a pumped well having a string of sucker rods connecting to a downhole pump, hydraulic pumping apparatus is disclosed. In the preferred and illustrated embodiment, a polished rod is surrounded by a selectively located sleeve. The sleeve locks to a piston in a hydraulic cylinder. The piston is forced upwardly. The length of stroke is adjusted. The location of the sleeve on the polished rod is likewise adjustable. This enables the device to be adjusted so that any length of sucker rods can be accommodated without requiring cutting sucker rods to achieve a particular length. Moreover, the length of stroke is adjustable to take into account the stroke of the pump and sucker rod elongation during operation.

Abstract: An actuator control system is disclosed using fluid dispensing means to selectively add or remove fluid from a closed actuator system, whereby the movement of the actuator is volume rather than pressure responsive.

Abstract: An apparatus for controlling a hydraulic turbine is disclosed comprising a hydraulic circuit to control the positioning of turbine runner blades and a hydraulic circuit to control the positioning of turbine wicket gates. The runner blade hydraulic circuit comprises a solenoid valve for normal operation of the blades and a slow rate servovalve for moving the blades when the actual blade position differs from a desired position by less than a predetermined tolerance. The wicket gate circuit comprises a solenoid valve for normal control of the gates. A diverter directs flow from the solenoid valve to a flow rate control valve when the difference between the actual and desired position of the gates is less than a second predetermined tolerance.

Abstract: The drive system for cells for fused salt electrolytic production of aluminum is supplied with compressed air via a compressed air network with compressor and compressed air reservoir. It comprises at least one working cylinder with piston and piston rod, a slide valve situated after the junction from the compressed air network, compressed air pipes and a microprocessor. During the thrust movement in the normal work cycle, the working cylinder forms a circuit together with a 5/2 channeling valve, a 3/2 channeling valve and the related compressed air pipelines; the said circuit is fed compressed air via a pressure reducing valve and the compressed air pipeline running from it. By briefly switching over the 5/2 channeling valve normal pressure can be employed and the positive chamber of the working cylinder evacuated, as a result of which the thrusting force supplied by the system can be greatly increased.

Abstract: A control valve includes a monolithic valve body incorporating dual digital valves and dual by-pass valves interconnected with each other by ducts within the valve body and providing for either controlled or uncontrolled actuation of a piston in either a forward or a reverse direction of movement.

Abstract: A hydraulic control arrangement for providing synchronism of a return cylinder between a face conveyor and a support, has a pushing cylinder which displaces the support transverse to a face, a control valve, a control cylinder influencing loading of the pushing cylinder via the control valve, and a control column provided between the return cylinder and the control cylinder and composed of a working fluid.

Abstract: A pump 1 supplies hydraulic fluid from a reservoir 2 to hydraulically operated equipment 4 through a main flow line 3, the fluid being returned to the reservoir 2 through a return supply line 5. If the pump 1 should fail the equipment 4 may be supplied from an independent pump unit which can be connected to flow and return lines 6, 7. Because the pump 1 has failed it will be incapable of operating a dump valve 15 so the fluid will not be fed to the reservoir 2. Should there be a blockage in the equipment 4 pressure will build up in a relief valve 13 which will therefore open to allow the fluid to pass directly to the return line 5 (or 7). If the system is to be used as a source of pressurized hydraulic fluid for another unit then a change over valve 12 will be operated to de-couple the unit 4 and allow the fluid to pass to the other unit through the auxiliary supply lines 6, 7.

Abstract: A hydraulic drive system for civil engineering and construction machinery in which at least first and second hydraulic circuits having at least first and second hydraulic pumps, respectively, are provided for driving a plurality of actuators such as left and right travelling actuators, a boom actuator and an arm actuator. The first circuit includes a first travelling directional control valve for one of the left and right travelling actuators located downstream of a first boom directional control valve for the boom actuator and a first arm directional control valve for the arm actuator that the latter to receive a hydraulic fluid supply from the first pump by taking priority over the first travelling valve.

Abstract: A multiple control valve system comprises the first and second multiple control valves. To the first multiple control valve an additional attachment valve is operatively connected in a manner that pressurized oil is supplied to the first multiple control valve and the attachment valve from a common oil pump independently through respective conduits. The second multiple control valve is connected to the attachment valve through a conduit to which a remote control valve is disposed thereby to change over flow direction changeover valves contained in the attachment valve and the second multiple control valve to simultaneously operate these valves.

Abstract: A hydraulic circuitry for a backhoe in which a hydraulic motor for driving one of right and left crawlers and a hydraulic cylinder for vertically oscillating a working arm assembly are connected in parallel to each other to a first pump through a multiplex valve assembly having a first center bypass, and a hydraulic motor for driving the other crawler, a hydraulic motor for slewing a platform, a hydraulic cylinder for flexing and stretching the arm assembly, a cylinder for actuating a bucket and a cylinder for actuating a dozer are connected in parallel to one another to a second pump through a further multiplex valve assembly having a second center bypass. The invention provides a circuit to permit fluid pressure from the first pump to enter the circuit connected to the second pump to provide confluence therein, when the dozer actuating cylinder connected to the second pump, for example, is operated while the backhoe is running.

Abstract: Pipe thrust-jacking apparatus includes a pressure ring 5 which is advanceable by a plurality of hydraulic rams 3. The rams are controlled by hydraulic control means having a plurality of hydraulic control valves 19. Each control valve is associated with a respective hydraulic ram, and is connected to a first input line and to a second input line. Each of the first input lines is connected to a respective hydraulic fluid feed line 9, and each of the second input lines 17 is connected to a common hydraulic fluid supply line 11 and to an auxiliary pump P2. The common supply line is connected to all of the feed lines. Means 12,15 are provided for selectively connecting each of the hydraulic control valves to its first input line and/or its second input line.

Abstract: A vacuum source device of vacuum booster is disclosed. The device includes an air ejector having an air inlet communicated with the atmosphere, an air outlet connected to a vacuum pick-up port opening to the portion of the intake system of an internal combustion engine downstream of a throttle valve, and a pressure reduction chamber connected to a vacuum chamber of the vacuum booster. A by-pass passage connecting between the vacuum pick-up port and the vacuum chamber of the vacuum booster by detouring the diffuser of the air ejector imposes a smaller flow resistance than the diffuser. A first check valve is disposed in the by-pass passage, while a second check valve is disposed between the by-pass passage and the vacuum chamber.

Abstract: An assistor for reducing stepping force of a clutch pedal, in which a push rod is inserted into an assistor casing freely movably in the axial direction, a casing outside end of the rod is interconnected to a clutch pedal, a casing inside portion of the rod is provided with a piston which divides the casing into first and second chambers, the first chamber intercommunicates with atmosphere, the second chamber intercommunicates freely changeably with atmosphere and a negative pressure source through a change-over valve mechanism, and the piston is interlocked with the change-over valve mechanism through the means of a negative-pressure setting spring so that negative pressure for reducing stepping force can be fed into the second chamber according to a shifted length of the rod.

Abstract: A control arrangement for a hydraulic motor has an adjustable pressure medium supply device with a container, an unblockable check valve with a control connection, a plurality of chambers including a supply chamber, a motor chamber, first and second return chambers, and a control chamber, a control slider displaceable relative to the chambers, wherein a control conduit extends from the supply device and leads to the control chamber, a first pressure control member is arranged on the control slider so that in a lowered position of the latter the first pressure controlling member is located between the control chamber and the second return chamber and the control slider in its raised position blocks the control chamber, and a second pressure controlling member located between the control chamber and the motor chamber and opening into the latter.

Abstract: A hydraulic brake booster comprises a housing forming a pressure chamber and a pair of bores leading to the pressure chamber. One of the bores receives an output piston and the other bore receives a valve member. The valve member is movable by an input actuator to control communication of fluid pressure to the pressure chamber. The end of the valve member within the pressure chamber carries a sleeve and a poppet. The sleeve resiliently imparts movement to the valve member and the poppet cooperates with the sleeve to close communication to the pressure chamber in response to movement of the sleeve relative to the valve member.

Abstract: A hydraulic fluid circuit of a hydraulic shovel including a first directional control valve group connected to a first hydraulic pump and including a first directional control valve and a second directional control valve respectively connected to a first hydraulic cylinder and a second hydraulic cylinder. A second directional control valve group, connected to a second hydraulic pump, includes a third directional control valve having a first working port connected to one cylinder chamber of the first hydraulic cylinder and a second working port connected to one cylinder chamber of the second hydraulic cylinder.

Abstract: A hydraulic circuit system of a construction machine having first and second hydraulic circuit, and a bypass circuit for connecting the first and second circuits together. The first circuit includes a first hydraulic pump and a first valve group having a plurality of directional control valves for controlling a flow of hydraulic fluid from the first pump, and the second circuit includes a second hydraulic pump and a second valve group having a plurality of directional control valves for controlling a flow of hydraulic fluid from the second pump. A plurality of actuators are driven by the hydraulic fluid supplied from the first and second pumps through the valves. The bypass circuit includes a bypass line for connecting the first travel valve in series with the second travel valve in a position downstream thereof through the selecting valve.

Abstract: The present invention relates to a device for controlling two fluid-controlled drive members, one of which is double-acting, wherein a communication conduit connects the supply conduits of said double-acting drive member, a non-return valve being disposed in said communication conduit and allowing the passage of the fluid solely from the small chamber towards the large chamber of said double-acting drive member, while another conduit is adapted to connect the large chamber of the double-acting drive member to the chamber of the second drive member. The result of the invention is the elimination of lift of a hydraulic loading shovel when digging.

Abstract: A control valve cartridge which may be seated within the end plate of an actuator cylinder has a number of two way, two position solenoid valves placed in series axially and by way of which the space on each side of the piston may be connected by a respective control valve cartridge with a high pressure source or a low pressure source so as to give a programmable choke function.

Abstract: A quick changeover hydraulic circuit for use in an auger drive mode or percussion hammer mode, controllable in each mode by the same flow regulator. The circuit comprises a first branch circuit which powers a first auxiliary hydraulic powered device and a hydraulic motor for drill steel rotation. A second branch circuit powers a hydraulic percussion motor for a drill steel hammer or a rotary hydraulic motor for an auger, only one of which is in the circuit at one time. An interbranch circuit comprises a priority flow divider which distributes flow. In a first mode with the percussion motor for the drill steel hammer connected into the second branch the flow is delivered to the steel rotation motor and the first auxiliary device. In a second mode with the auger motor connected into the second branch, combined flow from both branches is delivered to the auger motor.

Abstract: This relates to a pneumatic feed system for moving a labeler head of a labeling apparatus for depositing labels in mold halves of a blow molding apparatus. The relatively heavy labeler head must be rapidly accelerated and then rapidly decelerated and at the same time moved sufficiently so as to provide for a large number of back and forth cycles per minute. There is provided in association with compressible shock absorbers a pneumatic system including a high pressure supply and a low pressure supply together with throttle valves such that the gas in the unpressurized end of the cylinder is rapidly compressed near the end of the stroke to function as a shock absorber and further, the cylinder is of a much larger diameter than that required for moving the labeler head so as to permit for the rapid acceleration as well as the rapid deceleration.

Abstract: A tool (15) to be ground is mounted in a vertical position to the upper end of a vertically oriented piston (21). The lower end of the piston (21) is received into the open end of a cylinder (22). Radial fluid bearings (28, 29) are pressurized to permit rotational and longitudinal movement of the piston (21) with respect to the cylinder (22). Pressurized fluid is delivered to the piston (21) to exert a force on the piston (21) that nearly counterbalances the combined weight of the piston (21) and the tool (15). Additional fluid pressure or some other suitable force is applied to move the piston (21) and the tool (15) axially upwardly. At the end of the upward stroke, the additional force on the piston (21) is removed to allow said combined weight to move the piston (21) and the tool (15) downwardly. During the upward stroke, the downward stroke, or both the upward and the downward strokes, a grinding wheel (13) is held in a fixed position to contact a side surface of tool (15).

Abstract: The control mechanism is for pneumatic apparatus of the kind comprising a piston-and-cylinder motor coupled between two relatively-movable parts (such as door-leaves) for driving them, when energized, to a predetermined relative position. A pilot valve is actuated when required to switch the apparatus to an emergency mode by isolating the motor from its power source and discharging it into an emergency reservoir having a volume large compared with the maximum volume of gas in the motor. While the pilot valve is actuated, the relatively-movable parts are urged towards their predetermined relative positions by a force small compared with the normal operating force. The pilot valve may be arranged to operate operation of an emergency release bolt, on obstruction detected by a detector valve (in which case a timing reservoir provides time delay before full power is restored), on power failure, or as required.

Abstract: A self-leveling series type hydraulic system including boom and bucket valves which separately control boom and bucket cylinders and a flow divider valve positioned in the exhaust flow path from the rod end of the boom cylinder. The flow divider valve splits the flow sending a portion of it to the cap end of the bucket cylinder so as to maintain the bucket in a level condition during raising of the boom with the remaining flow connected to one of the boom valve motor ports whereby the bucket valve can be separately actuated concurrent with the boom valve and supplied with oil so as to override the self-leveling function if desired.

Abstract: A hydraulic interlock system is disclosed wherein several pumps may be used to activate a plurality of hydraulic circuits while preventing activation of a single hydraulic circuit by more than one pump simultaneously.

Abstract: A hydraulic brake booster includes a housing (22) with a control valve assembly (34) and a piston (30). The control valve assembly (34) carries a secondary valve assembly (56) including a pilot member (58) and a mounting ring (60). The secondary valve assembly controls communication of fluid pressure to the pressure chamber (24) via the control valve assembly (34).

Abstract: A control system for a hydraulic actuator comprising a first pump with large displacement capacity, a second pump with small displacement capacity, a pilot pump, a first pilot operated spring centered control valve connected at the input side thereof to the first pump, the output side of which is selectively connected to the hydraulic actuator and drain, a second pilot operated spring centered control valve connected at the input side thereof to the second pump, the output side of which is selectively connected to the hydraulic actuator and drain, and a third control valve for pilot pressure connected at the input side thereof to the pilot pump, the output side of which is connected to the first and second control valves wherein the second control valve is adapted to be actuated by a pilot pressure lower than a pilot pressure which actuates the first control valve.

Abstract: A hydraulic control system of a transport vehicle, wherein the flow of hydraulic fluid from the source of pressure is fed to the servomotor through a control hydraulic circuit which incorporates a fluid directional control device mechanically linked to a steering unit of a transport vehicle, a number of hydraulic lines and at least one throttle regulator, and through the actuating hydraulic circuit which incorporates a number of hydraulic lines, a throttle regulator and a discrete-type three-position fluid directional control device controlled by a pressure of the fluid flows admitted along the hydraulic lines communicated with the fluid directional control device of the control hydraulic circuit.

Abstract: A fluid motor control system (11) assures that automatic changes of motor displacement, which are initiated by occurrence of a predetermined operational condition in the system (11), result in a change of motor speed of the desired magnitude. Flow adjustment elements (76) respond to a displacement increase by reducing the flow of working fluid available to the motor or motors (12, 13) and respond to a motor displacement reduction by increasing the available flow. In one specific form, the system (11) controls a pair of right and left side vehicle drive motors (12, 13) and automatically increases motor displacements while reducing the fluid flow supplied to the motors (12, 13) to reduce travel speed during a turn of travel direction.

Abstract: A method and apparatus uses energy in an energy output system having a main power source, an energy transmission system and a mechanical output. A first portion of energy generated with the main power source is used to drive the mechanical output under operating conditions. The unused second portion of the energy is diverted to an energy storing means. The second portion of energy is then stored and regenerated on demand. The energy may be used directly to augment the energy requirements in the energy output system during peak periods. In a specific embodiment, a compressed air system is used for storing the energy not used in driving a mechanical output connected to the power source by an energy transmission assembly. The energy transmission in the energy output system is a hydraulic fluid transmission system. A hydraulic fluid diverting mechanism is used to maintain the flow of hydraulic fluid to the mechanical output and to the compressed air energy storage system.

Abstract: A circuit for hydrostatically operable devices, especially hydraulic dredges, with at least two working circuits each of which comprises a plurality of hydraulic cylinders and/or hydraulic motors as well as a hydraulic pump while, depending on the requirement, the delivery of the pertaining hydraulic pump is conveyed to each hydraulic cylinder or hydraulic motor and while by means of a plurality of tie lines the deliveries of the remaining hydraulic pumps are selectively conveyed to one of two or more selected hydraulic cylinders or hydraulic motors. The deliveries of the hydraulic pumps flow to the tank after having passed through the control valves associated with the hydraulic cylinders and controlling each of the hydraulic pumps.

Abstract: An actuator system is disclosed which modulates a linear output shaft associated with a working control valve or the like in response to a control signal input. The system includes a feedback control link, a pneumatic positioner, a pneumatically controlled hydraulic valving system and a hydraulic cylinder and piston assembly controlled by the hydraulic valving system. The hydraulic valving system includes a three-position, four-way valve actuated by pneumatic binary output signals from a signal conditioner which is in turn controlled by the positioner. Hydraulic flow to the three-position, four-way valve may also be controlled from the signal conditioner in response to positioner output for most effective actuation of the hydraulic cylinder and piston assembly. Failure modes are also disclosed with the present system. The resulting system exhibits extremely rapid response times and high accuracy with dynamic stability.

Abstract: A priority flow divider is disclosed for dividing hydraulic fluid flow between a steering circuit and an auxiliary circuit thereby providing better efficiency and greater productivity for the auxiliary circuit. The priority flow divider includes a cylindrical housing having a slidable spool valve therein, and the housing further includes an inlet port connected to the steering pump in the steering circuit, a discharge port connected to the steering valve, in the steering circuit, and a discharge port connected to the auxiliary hydraulic circuit. The spool valve has enlarged cylindrical portions which are connected by recessed connecting portions of a reduced diameter.

Abstract: A hydraulic system for precise positioning of a control device, such as a valve actuator. A double-acting, hydraulic cylinder, which operates the control device, is held in any set position by a hydraulic lock ensured by one-way check valves which prevent interflow between the chambers on opposite sides of the piston. Occurrence of a signal indicating a need to change position activates one of two three-way directional control valves allowing exhaust flow from the appropriate cylinder volume. Connected in parallel in the exhaust line is a plurality of on-off valves, each having a flow capacity that is some multiple of that of the next smaller valve, e.g. twice as large. This provides a wide range of distinct and precise flow capacities to provide close and instantaneous control over rate of movement of the positioning device.

Abstract: A hydraulic brake booster defines a pressure chamber (24) and includes a control valve (26). A sleeve (40) on the control valve includes a spacer (58) and the control valve includes an annular member (60). The spacer is engageable with a booster housing (14) to limit movement of the sleeve and the annular member is engageable with an accumulator valve assembly (32) during a failure mode to provide a safety power assist. The spacer is also maintained in spaced relation to the accumulator valve assembly.

Abstract: A power brake system has a brake booster operable by differential air pressure provided by a source of vacuum and a source of compressed air pressure. The differential air pressure control valve assembly of the invention maintains a substantially constant available differential of air pressure between the vacuum and compressed air pressures available to the brake booster for booster operation. In the charging mode it directs air pressure from an air pressure pump to an accumulator connected to the pressure inlet side of the booster, charging until the desired pressure differential is attained. In the storage mode, the air pressure from the pump is permitted to flow in its usual manner to another device or circuit utilizing the air pressure. This may be, for example, a part of the vehicle engine emission control system. In the pressure relief mode, the control valve vents excess accumulated pressure to exhaust.

Abstract: A hydraulic brake booster includes a housing which defines a pressure chamber and a piston within the housing is movable in response to pressurized fluid within the pressure chamber to effectuate a brake application. The piston encloses a storage chamber and forms a passage communicating the storage chamber with the pressure chamber. A valve member is disposed within the passage to control communication between the storage chamber and the pressure chamber. An operator actuator cooperates with a control valve to communicate pressurized fluid to the pressure chamber and a finger is actuated by the operator actuator to engage the valve member, thereby opening communication between the storage chamber and the pressure chamber. The valve member comprises a unitary assembly having a sleeve sealingly engaging the wall of the piston passage, a seat member biased into engagement with a shoulder defined by a stepped bore on the sleeve, and a stem extending through a bore on the seat member.

Abstract: A pneumatic actuating arrangement for to and fro movements, especially of a central locking system for motor vehicles, with an excess pressure source and with a vacuum source and with at least one pneumatic working device whose working chamber is adapted to be selectively connected to the excess pressure source or to the vacuum source by way of a shifting valve shiftable between two end positions. An intermediate for the shifting valve is provided in which position the shifting valve becomes temporarily effective during the transition from the one end position into the other end position so that the working chamber is conected to the atmosphere.

Abstract: A fluidic driver amplifier for a servovalve has its controllably directed fluid jet differentially divided by a divider element which moves with a main valve piston in a manner to equalize the differential pressure received from the jet when the piston reaches the commanded position. In order to permit use of a small, low-leakage, fluidic driven amplifier, without the disadvantage of reduced speed of response, a derivative piston is linked to move with the main piston and displace fluid in a chamber containing a spring-centered secondary valve piston. When displaced, the secondary piston admits pressurized fluid into the main valve chamber in a positive feedback sense to aid the fluidic driver in positioning the main piston. The secondary piston is displaced only when the main piston is in motion and therefore has no effect once the main piston reaches the commanded position.

Abstract: A hydraulic brake booster provides a housing within which a spool valve is slidably mounted. The housing forms a pressure chamber and the spool valve is movable from a first position venting the pressure chamber to a second position, communicating the pressure chamber to a fluid pressure source as the spool valve moves toward the second position. A piston or cylindrical accumulator is also slidably mounted in the housing and moves in response to pressurized fluid in the pressure chamber to actuate braking. In order to hydraulically actuate braking when the pressure source is disabled, the piston includes a storage chamber within which pressurized fluid from the pressure chamber is stored. With the source disabled an operator actuating means moves the spool valve to the second position to close the pressure chamber to the pressure source.

Abstract: A hydraulic power brake system in which a hydraulic power brake booster has an accumulator operable when there is insufficient power to operate the power brake with hydraulic pressure. The accumulator control valve is actuated by a cylindrical cam normally radially displaced so that its axis is not coincident with the axis of the booster. Sufficient actuating movement of the control portions of the booster cause the cam to move axially and radially so that its axis moves in a direction to be coincident with the axis of the booster, causing the accumulator control valve to be opened in a controlled manner and admit accumulator pressure to the booster power chamber.

Abstract: The invention relates to an actuator device for a motor vehicle speed-responsive system, the device being operable to actuate the throttle valve or the like of the internal combustion engine of the vehicle. The actuator device comprises a bellows device defining a first chamber partly bounded by a movable wall and a fixed wall, and communicating with two further chambers defined by associated housings carried by the said fixed wall. One of the further chambers contains a first electro-magnetic control valve fed by a D.C. voltage, and operable to control an orifice through which the first chamber communicates with atmosphere. The other of the further chambers contains a second electro-magnetic control valve fed both by said D.C. voltage and by a pulsed voltage, and operable to control both an orifice through which the first chamber communicates with atmosphere and an orifice through which the first chamber communicates with a source of gas at sub-atmospheric pressure.

Abstract: A hydraulic brake booster is disclosed which includes an integral accumulator to provide a fluid pressure source for emergency failsafe braking. The accumulator includes a bore defined within the booster housing, and a piston slidably mounted in the bore which divides the latter into a pair of fluid compartments between opposite ends of the piston and corresponding ends of the bore. One of the compartments is communicated to the booster inlet port so that the compartment is charged with fluid pressure whenever the pressure level at the inlet port is above some predetermined low value. In one embodiment of the invention, the other compartment is communicated to the fluid pressure reservoir, and a relief valve is carried within the piston which controls flow of fluid between the two compartments.