Abstract: The present invention is drawn to an isolation system for separating two diverse fluid mediums from each other and, more particularly, an isolation system for prohibiting leakage of the diverse mediums around the peripheral surface of a piston movably mounted within a chamber. The present invention further relates to an improved multi-piston air-oil pressure intensifier employing the improved isolation system for separating and preventing leakage of the air and oil mediums during operation of the pressure intensifier.

Abstract: The hydraulic cylinder comprises a cylinder jacket (1), a piston-rod guide flange (2), and a cylinder bottom (3). Disposed within the cylinder are a primary piston (4) provided with a piston rod (6) and a secondary piston (11) connected to two plungers (7, 8). The plungers enter two bores (5, 6) in the primary piston. Two spring-biased (19, 20), openable check valves (17, 18) are disposed in the cylinder bottom. In each valve there is a bore (41, 42) connecting the front and rear sides of the valve. The rear portions (24, 25) of the valve chambers (26, 27) each contain a spherical unstopping piston (21, 22). Two supply ducts (23, 30) for the hydraulic fluid are connected to the valve chambers, these chambers in turn having supply ducts at various locations (36, 40, 45) of the interior of the cylinder. A very compact construction is possible for the hydraulic cylinder with pressure transmission.

Abstract: In a hydraulic cylinder apparatus of a type actuated by a booster, a plunger chamber (39) of a booster (32) is connected in communication with an extension cylinder chamber (35) of a hydraulic cylinder (30). An annular oil make-up chamber (48) is disposed outside an outer peripheral surface of the cylinder chamber (35). The oil make-up chamber (48) is connected in communication with the plunger chamber (39) and an electromagnetically opened and closed type shutoff valve (49) is interposed between both said chambers (39) (48).

Abstract: A hydraulic vehicle brake system of the type having a high system return pressure is provided. In order to minimize the size and strength of brake return springs required, the invention provides a device to be interposed between the brake and the brake control valve. Preferred embodiments of the device include an inlet port communicating with a brake valve and an outlet port communicating fluid pressure to a vehicle brake. A control assembly is provided intermediate the inlet and outlet ports and includes mechanisms for amplifying the hydraulic pressure effect in the direction from the outlet port to the return pressure system so that the brake return pressure exerted by the brake return springs can be substantially less than the hydraulic system return pressure.

Abstract: A tandem master brake cylinder has first and second pistons, each piston associated with a fluid chamber and a pressure chamber. The pistons are displaced in response to actuation of a brake pedal. A hydraulic booster is coupled to a power source and is operable to enhance the piston movement and for conducting pressurized fluid to a second of the fluid chambers associated with a second piston to displace that piston in a manner reducing the volume of the pressure chamber associated with the first piston. In the event that a negative pressure is communicated with the second fluid chamber, e.g. by a loss of pressurized fluid from the power source, brake fluid is supplied through a one-way check valve to the second fluid chamber to prevent the negative pressure from reversing the motion of the second piston.

Abstract: The subject invention comprises a hydraulic pressure intensifier (10) including a cylinder (42) having a fluid inlet (44) at one end and a fluid outlet (46) at the other end. Two telescopically disposed pistons (54, 56) are slideably supported between the inlet (44) and outlet (46) ends of the cylidner (42). A spring (60) extending axially through the cylinder (42) urges the pistons (54, 56) toward the inlet end (44) of the cylinder (42). A spring biased valve member (70) seals a flow passage (62) extending through the pistons (54, 56) when the fluid pressure reaches approximately 150 psi at the inlet (44) to the cylinder (42). A pin (68) fixed to the inlet end (44) of the cylinder (42) actuates the valve member (70). The pistons (54, 56) move first in unison and then separately toward the outlet end (46) of the cylinder (42) as the hydraulic pressure increases at the inlet end (44).

Abstract: A hydraulic braking system includes a tandem master cylinder having a bore with an opening and a closed wall at opposite ends thereof which formed in a housing, a first piston slidably fitted in the bore so as to define a first pressure chamber and a first fluid chamber therein and operatively connected to a brake pedal, a second piston slidably fitted in the bore so as to define a second fluid chamber adjacent to the first pressure chamber and a second pressure chamber and operatively connected to the first piston. A normally open valve communicates with each piston so as to close passages formed in the each pistons and communication between each fluid chambers and each pressure chambers, respectively, when each piston is moved in response to the depression of the brake pedal. A power source generates a hydraulic power pressure.

Abstract: A pressure intensifier comprising a housing incorporating a first floating piston-cylinder unit with means to supply a primary pressure fluid medium to one side of the piston to apply pressure to a fluid medium in contact with the other side of the first piston, a second floating piston unit provided with a fluid medium communication port therethrough, there being direct communication between the medium contacting the other side of the first floating piston with one side of the second floating piston and through the port thereof to a fluid medium pressure power take-off chamber, the port of the second floating piston being closeable by means of a valve comprising two active parts, one part of which is incorporated in the second floating piston and the other part of which is provided with limited movement with respect thereto, there being means to apply primary fluid pressure to the other side of the said second floating piston to maintain the communication port open, the other part of the valve being constitu

Abstract: The subject invention comprises a hydraulic pressure intensifier (10) including a cylinder (42) having a fluid inlet (44) at one end and a fluid outlet (46) at the other end. Two telescopically disposed pistons (54, 56) are slideably supported between the inlet (44) and outlet (46) ends of the cylinder (42). A spring (60) extending axially through the cylinder (42) urges the pistons (54, 56) toward the inlet end (44) of the cylinder (42). A spring biased valve member (70) seals a flow passage (62) extending through the pistons (54, 56) when the fluid pressure reaches approximately 150 psi at the inlet (44) to the cylinder (42). A pin (68) fixed to the inlet end (44) of the cylinder (42) actuates the valve member (70). The pistons (54, 56) move first in unison and then separately toward the outlet end (46) of the cylinder (42) as the hydraulic pressure increases at the inlet end (44).

Abstract: A hydraulic braking system having an auxiliary piston disposed between an input piston and a presser piston, so as to define a first power chamber between the auxiliary and presser pistons, and a second power chamber between the input and auxiliary pistons. The presser piston cooperates with a housing to define a pressure chamber connected to a first braking arrangement. The first power chamber is connected to a second braking arrangement and supplied with a power pressure from an external hydraulic source through a control valve and the second power chamber. The system includes a connecting mechanism connecting the auxiliary and presser pistons such that the two pistons are normally placed in a spaced-apart state but are abuttable on each other.

Abstract: A hydraulic control circuit and method of operating a blowout preventer having a two-way hydraulic piston and cylinder assembly including an open and close port. An adjustable hydraulic supply is connected to a control valve which is in turn connected to the open and close ports. A pressure booster having an input and an output is connected to the close port and a control circuit is connected to the input of the booster and to the close port for actuating the booster and also blocking flow from the control valve to the closed port when the hydraulic supply increases to a predetermined value.

Abstract: A vehicle brake system comprises two pressure modulators (16, 18) one of which (16) is associated with one of the brake circuits (12) and the other of which (18) is associated with the other (14) of the brake circuits. The modulators (16, 18) are accommodated in a housing, preferably in the form of a twin arrangement, and are actuated by means of a common drive unit. The pressure modulators (16, 18) each include a plunger piston (78) which is acted on by a differential gear in the common drive unit. In a first embodiment, a vacuum servo drive (20) serves as the drive unit and the differential gear comprises a linear guiding element (106) and an angular lever (112) articulated thereto. The force required to hold down the plunger pistons (78) in their initial position can be applied mainly pneumatically. A ventilatable chamber (M2) of the vacuum servo drive (20) being connected for that purpose with the ventilatable working chamber (B2) of a vacuum brake power booster (32 ).

Abstract: A hydraulic vehicle brake system having a brake booster disposed in a housing. The brake booster communicates via an energy supply system with a supply container and via shutoff devices with brake chambers that can be acted upon by plungers via the brake booster. The brake chambers are connected in turn via brake lines and incorporated shutoff valves to wheel brake cylinders of wheel brakes. A stop bushing surrounds the master cylinder piston and has a sleeve, and a spring is disposed between the sleeve and an annular stop integral with the housing. The stop bushing, an inner plunger face and the housing enclose a plunger chamber. In regulated operation, the plunger chamber likewise communicates with the energy supply system via the brake booster and corresponding lines. During normal brake operation the plunger chamber is connected to the supply container via a line connected to a reversible valve.

Abstract: An iosolation valve usable with an adaptive braking/traction control system comprising a plurality of passages adapted to communicate to a variety of pressure sources and an outlet port adapted to communicate to at least one brake cylinder. A valve movable to open and close one or the other of opposingly situated first and second passages to alternately communicate a master cylinder to the outlet port or a second pressure source to the outlet port so that when the first passage is closed by the valve the brake master cylinder is isolated from the brake cylinder.

Abstract: A hydraulic brake system includes a hydraulic power booster (11) and a master cylinder (12) connected downstream of the power booster (11). The pressure chamber (21) of the power booster (11) is pressurized by an auxiliary pressure which is dependent on the position of a pedal-actuated brake valve (19). A fast-fill cylinder (40) is can be pressurized by the dynamic pressure and with its aid the working chamber (16) of the master cylinder (12) can be supplied with additional pressure fluid in the initial phase of braking. The chamber (48) between the two piston steps (57, 58) of the fast-fill cylinder connects to the unpressurized supply reservoir (3) by way of a valve assembly (51) for synchronizing the movements of the master cylinder piston (43) and of the stepped piston (45) of the fast-fill cylinder (40). The valve assembly (51) is furnished with the wheel cylinder pressure as a control variable.

Abstract: This brake booster is for a vehicle whose tandem type brake master cylinder has a first piston and a second piston operating in tandem, with first and second pressure chamber and a reservoir chamber for the second brake fluid supply pressure chamber being defined in it. The brake booster has a power piston, one side of which is presented to an actuating pressure chamber, and which is driven by supply of pressurized brake fluid to that actuating pressure chamber so as to push the first piston of the master cylinder so as to expel fluid from the first and second pressure chambers towards the vehicle brakes. Brake fluid is supplied by a valve to the booster actuating pressure chamber upon brake pedal depression. A conduit is provided for directly conducting fluid from the actuating pressure chamber of the brake booster to the reservoir chamber for the second pressure chamber of the master cylinder.

Abstract: A hydraulic brake system for automotive vehicles has a master brake cylinder connected to an unpressurized reservoir and a brake line connected to a working chamber of the master brake cylinder and leading to pressure control valves of a brake slip control device. The pressure control valves are followed by wheel brake cylinders. The working chamber of the master brake cylinder is connectible to a pressure medium source upon the starting of the brake slip control device. The outlet pressure of the pressure medium source lies above the maximum braking pressure achievable by applying the master brake cylinder. The working chamber's front side (away from the first master cylinder piston) is sealed by a second master cylinder piston sealedly arranged within the master cylinder. The second master cylinder piston is sealed relative to the master cylinder by a non-return valve gasket.

Abstract: Hydraulic pressure transducer having an operating cylinder (10) with an operating piston (12) and operating piston rod (14) adapted for rapid traverse, and a transducer piston (22) and piston rod (24) guided within an axially connected power cylinder (20). The transducer piston rod (24) is of a smaller diameter than the operating piston rod (14) and is capable of plunging into the operating cylinder volume (16), the transducer piston rod (24) extending through a seal (58) separating said operating cylinder volume (16) from the power cylinder.

Abstract: Hydraulic booster comprising a housing provided with a bore inside which there is slidably mounted two pistons each associated with a respective pressure chamber intended to be connected to a respective brake circuit; an actuating piston slidably mounted inside the bore and intended to be displaced by a brake pedal, displacement of the actuating piston being capable of causing displacement of the two pistons; and two valve mechanisms each associated with a respective brake circuit and intended to control the flow of pressurized fluid from a respective source to the brake circuit, characterized in that the two valve mechanisms are arranged parallel to the bore and are intended to be actuated simultaneously by the actuating piston.

Abstract: To protect brake fluid against evaporation under extreme braking conditions, the brake fluid contained in the wheel brake cylinders is kept at a minimum pressure between 5 and 10 bar even after completion of a braking operation, thereby increasing the boiling point of the brake fluid. The wheel brake cylinders are designed as stepped cylinders with a counterpressure space, into which a likewise constantly kept counterpressure can be introduced, which maintains equilibrium with the admission pressure prevailing in the inlet pressure space of the respective wheel brake cylinder. A non-return valve arrangement, connected between the brake booster and the inlet pressure spaces of the wheel brake cylinders, blocks the return of the brake fluid to the brake booster when the pressure differential between the wheel brake cylinders and the brake booster drops below a threshold value P.sub.S.

Abstract: A brake system comprising a hydraulic braking pressure generator (1) to which are connected the brake wheels (6-9); an auxiliary pressure supply system including a hydraulic pump (10) and an auxiliary pressure control valve (12) causing an auxiliary-pressure proportional to the pedal force (F). Pressure-controlled multidirectional valves (27,28) are provided establishing a connection between either the braking pressure generator or the auxiliary pressure supply system and the wheel brakes (6-9). The pressure-controlled multidirectional valves (27,28) are structurally combined with a switching mechanism (41,42) to signal the operating condition of the brake system, in particular, a pressure breakdown or defective conditions of the valves. A connection is established, via one of the pressure-controlled multidirectional valves (27), between the pedal travel simulator and the braking pressure generator (1). The brake system can be applied to a slip-controlled system.

Abstract: A braking pressure generator for slip-controlled brake systems of automotive vehicles comprises dynamic (III) and static (I, II) pressure fluid circuits into which pressure fluid from the dynamic circuit (III) is metered during braking with slip control. A differential pressure pilot valve (4) is provided which compares the pressure in a booster chamber (15) of the hydraulic circuit (III) with the pressure in a prechamber (5) into which pressure is metered during braking with slip control. The differential pressure pilot valve (4) is connected to an alarm switch (9). The switching position of this alarm switch is logically combined with the switching position of a brake-actuating switch (8) and with the brake slip control signal (10) and an error signal is derived therefrom.

Abstract: The hydraulic power braking apparatus comprises a fluid power apparatus (10) receiving fluid pressure from a power steering apparatus of the vehicle, the fluid power apparatus (10) connected at one end to the brake pedal of the vehicle and at the other end to a master cylinder (110). The master cylinder (110) is connected to a fluid displacement multiplier (210), fluid pressure developed by the master cylinder being communicated to the fluid displacement multiplier (210). The fluid displacement multiplier (210) comprises a housing (212) having therein a stepped chamber (211) with a differential area piston (213), the differential area piston (213) having a through passage (240) controlled by a poppet valve (250).

Abstract: The invention concerns a hydraulic amplifier for a braking system incorporating a body (10, 110), a first component (18, 124) capable of being displaced in the body (10, 110) under the effect of the operation of a brake pedal, between a first position causing a first chamber (16), joined to a braking circuit, to communicate with a low pressure reservoir (44, 138), and isolating this chamber (16) from a high pressure source (32, 130), and a second position isolating the chamber (16) from the low pressure reservoir (44, 138) and causing it to communicate with the high pressure source (32, 130), characterized in that it incorporates a second chamber (12, 112) formed in the body (10, 110), a circuit (42) causing this second chamber (12, 112) to communicate with the low pressure reservoir (44, 138), and a valve means (34, 116) responsive to the pressure of the high pressure source (32, 130) normally closing this circuit under the effect of the pressure of the high pressure source (32, 130).

Abstract: The device incorporates an actuating piston (6) in tandem with a master cylinder piston (7) both defining first (8) and second (9) braking pressure chambers. A valve mechanism (34), in line with the control valve mechanism (12) of the device, is controlled by a mode selector piston (31) exposed to the actuating pressure coming from the source of fluid under pressure (25) so as normally to isolate the first chamber (8) of the braking circuit (I) joined to the working chamber (5). In the case of failure of the pressure source, the braking circuit (I) is joined to the primary chamber (8).

Abstract: A hydraulic cylinder device for power multiplication includes a cylinder (1) containing a single-stage piston (2) having a piston rod (4) and a two-stage secondary piston (3), the piston rod (4) extending through a bore in the secondary piston. The cylinder (1) is closed by a cylinder cover (16) through which the piston rod (4) also extends. Two stop-pistons (22, 24) with different strength springs (21, 23) are located in projection (20) integral with cylinder (1) and opposite the stop-pistons are two opening-pistons (33, 34).

Abstract: An actuating device for a vehicle hydraulic brake system of the type having electromagnetically operated valves in the hydraulic circuits to each wheel brake for providing slip control wherein the device includes a master cylinder having a brake pedal force responsive hydraulic booster piston for actuating a master cylinder piston slidably mounted within a slidable positioning sleeve within the bore of the master cylinder. The positioning sleeve is adapted to be mechanically coupled to the booster piston in the brake actuation direction. A stationary projection on the interior end of the master cylinder protrudes into the positioning sleeve and cooperates with the sleeve and master cylinder piston to vary the master cylinder volume.

Abstract: This invention relates to a hydraulic brake system for automotive vehicle with a master cylinder (2) and with a hydraulic power booster (1) connected upstream of the master cylinder (2) and having a pressure chamber (4) in which an auxiliary pressure depending on the actuating force (F) may be modulated via a pedal-operable brake valve (7). Wheel brakes (51, 53) of a first brake circuit are connected at the pressure chamber (4), wheel brakes (50, 52) of a second brake circuit being connected at the master cylinder (2). The braking pressure active in the wheel brakes (50 through 53) is controllable by valve members (39, 54 through 59) controllable in dependence on the slip. In case of control, a hydraulic communication will be established between the pressure chamber (4) of a hydraulic power booster (1) and the master cylinder.

Abstract: The present invention relates to a dual-circuit hydraulic brake system with slip control, in particular for automotive vehicles, wherein wheel brakes (26, 27, 41, 42) are connected via electromagnetically actuatable multiple-position valves (38, 39, 88, 40, 24, 89) to brake circuits which are hydraulically isolated from one another, wherein the brake circuits are adapted to be pressurized by a tandem master cylinder (1), on the one hand, and are connectible to a dual-circuit pump aggregate (76, 77) adapted to be driven electromotively, on the other hand. Both outlets of the pump aggregate (76, 77) are connected to normally closed brake valves (43, 44) which are governed by the master cylinder pressure and separating valves (11, 12) which are adapted to be closed by the outlet pressure of the brake valves (43, 44) are inserted into the connections between the tandem master cylinder (1) and the wheel brakes (26, 27, 41, 42).

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 dual-circuit tandem main brake cylinder which includes at least one closed brake circuit (I) having a brake piston. This brake piston is actuated by means of the pressure fed into a pressure chamber by means of a brake control valve with a travel simulator spring. Adjoining this pressure chamber is also an auxiliary piston device, which comprises an auxiliary piston and a tappet passing therethrough and connected indirectly with the brake pedal. A highly progressive spring is fastened between the auxiliary piston and the tappet; this spring predominantly determines the pedal characteristic.

Abstract: An arrangement for controlling the admission of a hydraulic fluid to respective wheel brake actuating cylinders either from an auxiliary pressure source or from a master cylinder includes a pressure limiting valve and a hydraulically operatable switching valve including a valve body movable only when the auxiliary pressure source is fully operational from a first position in which it connects the master cylinder with the actuating cylinders to a second position in which it connects the auxiliary pressure source with the actuating cylinders and the master cylinder with the pressure limiting valve. The limiting pressure of the pressure limiting valve is adjusted in dependence on the brake pedal travel. The respective master cylinder piston carries a deflectable seal which permits fluid to flow past it in one direction but not in the opposite direction. The pressure at which the switching valve member moves into its second position has a predetermined level, preferably 1 to 2 bar gauge.

Abstract: The invention relates to a pneumatically controlled pressure transducer for operating hydraulic work tools having a dual operating cylinder, on one side of which a pneumatically operable piston, on the other side a hydraulically operable piston is provided and, to the hydraulic side of which a hydraulically operable working tool can be joined.The essence of the invention resides in that a control valve is provided which is coupled with the primary space located in front of the piston of the pneumatically operable cylinder of the operating cylinder and, which is connected into an operating relationship with a starting valve, and wherein the control valve is connected over a throttle-check valve to a further valve on one side, while on the other side, over a quick exhaust valve, is connected with a hydraulic container, respectively, over a valve with the secondary space of the pneumatically operable cylinder.

Abstract: An arrangement for controlling the supply of pressurized hydraulic fluid from a master cylinder and from a pressure source into hydraulic circuits leading to wheel brake actuating cylinders includes a valve device including a control piston acted upon by a spring-loaded auxiliary piston in one direction and by the pressure in a return conduit in the opposite direction. Upon brake pedal depression, hydraulic fluid pressure from the pressure source acts on the auxiliary piston in opposition to the spring force so that the auxiliary piston ceases to act on the control piston. Then, as hydraulic fluid is discharged from the brake actuating cylinders during antiskid control action, pressure builds up in the return conduit and propagates to the control piston to move the same into its open position in which it admits pressurized fluid from the pressure source to check valves which are acted upon in opposition to their opening by the tandem master cylinder pressures.

Abstract: The invention provides a power assisted hydraulic control system suitable for actuating clutches and brakes. The system incorporates a master cylinder having a master piston therein defining a control chamber, a hydraulic power assistance unit, and a distributor adapted to connect, by means of a slide valve, the power assistance unit with the hydraulic receiver controlling the brake or clutch unit. The distributor comprises a slide-valve having a plunger one end of which is subjected to the pressure in the control chamber and the other end of which is subjected to the pressure in the receiver.A bypass channel links the control chamber of the master cylinder to the pipeline connecting the operating port of the distributor to the receiver. The bypass channel has a bypass valve controlled by a spring which opens in the event of failure of the power assistance to permit manual operation by the master piston.

Abstract: A brake unit comprising a hydraulic booster unit connected to hydraulic auxiliary energy and controllable by a brake pedal via a control piston drives a master brake cylinder unit to supply brake pressure to wheel brake cylinders through at least one hydraulic line connected to an output of the master brake cylinder unit. A bypass line connected to the work chamber of the booster unit supplies a preliminary feed of the auxiliary energy to the wheel brake cylinders to overcome the brake clearance. A two way, two position changeover valve is connected to the hydraulic line, the bypass line and the wheel brake cylinders to connect during a braking operation either the bypass line or the hydraulic line to the wheel brake cylinders dependent on the pressure in the two lines. This brake unit requires only a few hydraulic connections external of the unit, has a single construction, has small dimensions, has exact operation and has quick response.

Abstract: A brake valve useable in conjunction with a vehicle braking system monitored by an anti-locking device and operable by a brake pedal through a trailing spring sometimes also called a simulating spring. The brake valve is provided with a control slide valve longitudinally displaceable by the trailing spring. The slide valve regulates a metered feed of the pressure medium conducted from a pressure source to the wheel brake cylinders. The pressure medium is relieveable at the wheel brake cylinders by anti-lock valves. The slide valve includes two control slide valves of which is associated with a pressure reservoir. One control slide valve cooperates with an emergency piston providing free through-flow during normal operation of the braking system. The emergency piston, upon a failure of the pressure medium source, after an emptying of the pressure reservoirs, is operable mechanically by the brake pedal after a spring-loaded ball valve has been closed at the emergency piston.

Abstract: The brake booster comprises a working piston for activation of a master cylinder piston and a transmitting piston having a greater diameter than the working piston in a tandem relationship with the working piston. A transmission pressure chamber is disposed between adjacent ends of the working piston and the transmission piston and a first valve arrangement is provided to load the transmission pressure chamber with pressure fluid or to relieve this chamber of pressure. A drive or actuating pressure chamber is disposed adjacent the other end of the transmission piston and a second valve arrangement is provided to load the drive pressure chamber with pressure fluid or to relieve this chamber of pressure. The first and second valve arrangements are controlled by the brake pedal and constructed in such a way that when the brake pedal is initially operated the brake pedal and the pistons come to a stop until all idle paths have been travelled.

Abstract: A fluid pressure intensifier in which a body has a side wall and first and second end walls. A tube extends inwardly in the body from the first end wall and a piston head is slidably disposed on the tube. A cylindrical element in spaced relation to the body side wall extends from the piston head toward the second end wall. A fluid inlet in the second end wall supplies pressurized fluid to move the piston head on the tube. A fluid outlet through the tube transfers pressurized fluid from within the element out of the intensifier. The amount of pressure intensification is proportional to the surface area differential of the piston head and a cross section of the element.

Abstract: In a boosted hydro-pneumatic drive for rapid traverse and power stroke, particularly for driving punching tools, a cylinder housing (1, 4) with partition (12), a disc piston (7) with plunger (8), a working piston (2) which can be loaded with compressed air for the return stroke and an annular piston (9) surrounding the plunger (8) are provided. The cylinder spaces between the working piston (2) and the annular piston (9) on both sides of the partition (12) are filled with hydraulic oil.In order to reduce the consumption of compressed air and to increase the speed of response, and for the purpose of simplification, the working piston (2) is provided with an annular surface (16a) which can be loaded with compressed air in the direction of advance, and a compression spring (10) is clamped between the disc piston (7) and the annular piston (9). The space accommodating the compression spring (10) is in constant connection with the outside air, preferably via a filter (11).

Abstract: The object of the invention is a synchronized hydropneumatic control of clutch and gearbox.In accordance with the invention a hydropneumatic servomotor clutch control has been provided which includes a jack the piston of which is assisted by a pneumatic motor and a master cylinder which feeds the said jack with hydraulic fluid and controls the feed of air to the said motor, characterized in that the control chamber of the said jack is connected to the hydraulic circuit for locking/unlocking the gearbox, the feed to the said circuit being carried out through a valve mounted in the piston. The admission of the hydraulic fluid from the master cylinder having as its effect during a first period the closing of the said valve, thus interrupting the admission of fluid into the said chamber, then the causing of the transfer of the fluid contained in the latter towards the circuit for the gearbox which becomes unlocked in synchronism with the clutch.Application to controls of clutch and gearbox of vehicles.

Abstract: In an injection molding machine of the type comprising an injection cylinder, a feedback circuit for feeding back the oil in the rear chamber of the injection cylinder into the front chamber thereof and a booster cylinder, a pressure oil accumulator is connected to the booster cylinder through a valve for supplying pressurized oil for actuating the booster cylinder. A check valve is connected in parallel with the valve. When water hammer occurs at the end of the injection stroke the check valve opens to absorb the energy of water hammer by the accumulator.

Abstract: An apparatus for mixing and ejecting at least two interacting components to provide a foaming material. The apparatus comprises an injection head connected to supply circuits of the individual components, which head includes a mixing and ejecting chamber; the chamber has a cleaning plunger axially reciprocable therein and operated by a double acting cylinder connectable through a first sliding valve to a first pressure fluid supply conduit comprising a one-way valve, and respectively to a branched-off conduit connected to a pressure multiplier cylinder. The control side of multiplier cylinder is in turn connected to the pressure fluid supply through a second sliding valve operatively connected to the first sliding valve.

Abstract: A vehicular hydraulic brake apparatus comprises a tandem master cylinder having front and rear sections respectively connected by independent front and rear wheel braking hydraulic circuits to front and rear wheel brake cylinders. The rear wheel braking hydraulic circuit is provided therein with a deceleration-responsive braking pressure control device having pressure inlet and outlet normally communicated with each other. The pressure control device has an inertia valve comprising a ball and a valve seat and a first differential piston both disposed between the pressure inlet and outlet. When the deceleration of an associated vehicle reaches a predetermined value, the ball is moved to close the valve for thereby interrupting the communication between the pressure inlet and outlet. In normal operative condition of the apparatus, the differential piston is operative to modulate the inlet pressure after the valve closure and transmit the modulated pressure to the rear wheel brake cylinders.

Abstract: A combined hydraulic and vacuum booster includes hydraulic and vacuum boosters coaxially mounted in series and having a common force output member. The combined booster includes common operating means for energizing the boosters in sequence for first applying substantially the full force of the hydraulic booster to the output member while the vacuum booster is substantially inoperative, and then applying the force of the vacuum booster to the output member.

Abstract: An operator cylinder comprising, in combination with a hydraulic piston-cylinder unit, an idle transmission piston for supplying to the hydraulic cylinder a pressure of control, and a stress multiplier for supplying when necessary an increased pressure simultaneously excluding the operation of the transmission piston.

Abstract: A vehicle brake having a vacuum suspended operating section. The assembly is arranged so that initial braking is accomplished by the operator admitting atmospheric pressure to the pressure side of a diaphragm that has a vacuum on its opposing side. The assembly is further arranged so that the wheel cylinder can be used to convert hydraulic pressure to air pressure. When the vehicle operator first applies a force to the brake pedal, a valve is actuated which allows vacuum and atmospheric pressure to impart sufficient force to provide initial braking. When greater brake pressures are required as indicated by increased brake pedal force exerted by the vehicle operator, a valve leading to atmospheric pressure closes, allowing the hydraulic pressure in the wheel cylinder to convert the trapped atmospheric pressure to air pressure.

Abstract: This invention embodies an intensifier cylinder assembly within the main hydraulic ram of a plastic molding machine whereby the clamping force holding the mold halves together can be increased during the shot cycle of the machine by at least three times the normal clamp force of the machine. Additionally, the location of the intensifier reduces the number of high pressure hydraulic fittings in the machine improving the safety factor while reducing the overall cost of the intensifier itself since the ram piston now becomes the housing for the intensifier piston.

Abstract: A hydraulic brake force-multiplying device includes a body, an output member fitted slidably in the body, a working chamber defined between the output member and the body, a pressure chamber defined in the body and receiving pressure fluid introduced from a source of pressure fluid, a valve seat member positioned in the pressure chamber and urged against the body under fluid pressure of the pressure chamber, a rod member provided integrally with the valve seat member and extending to the interior of the working chamber, a guide bore extending through the rod member axially, a valve stem having a valve portion adapted to cooperate with a valve seat of the valve seat member, thereby forming a valve mechanism in combination with the valve seat, and being sealingly and slidably fitted in the guide bore, an input shaft provided in the body adjacent to one end of the valve stem remote from the working chamber, an intermediate chamber defined between the input shaft and the valve stem and adapted to be communicated