Abstract: A pneumatic control system for selectively controlling a pneumatically-operated device for controlling movement of a variable load, such as a material handling device or lifting and lowering device, is capable of automatically sensing the load exerted on the pneumatically-operated device and automatically self-compensating for varying loads in order to selectively maintain the load in a static condition. The system further allows for ease of manual manipulation of the load to a new static condition and automatically self-compensates in order to maintain the load at such new static condition. The system preferably accomplishes this by automatically detecting the outlet pneumatic pressure necessary to maintain the load in a first static condition and for automatically self-adjusting the outlet pneumatic pressure to maintain the load in a second static condition.

Abstract: A hydrostatic steering valve utilizing a shaft mounted valve seat and a surrounding valve member which has no physical impediments such as a bearing or seal surrounding the valve member so as to allow the valve member to float with the valve seat totally unimpeded.

Abstract: A hydraulic booster equipped with an emergency accumulator, wherein reaction and power pistons are slidably fitted in a housing such that the two pistons define a power chamber therebetween. The booster includes a control valve having a normally closed power chamber passage formed therethrough so as to communicate with the power chamber, and a normally open passage connecting a pump and a reservoir. The valve is operated in response to an operation of the reaction piston, so as to restrict a fluid flow through the normally open passage from the pump toward the reservoir, thereby raising a pressure of the fluid delivered from the pump, and open the power chamber passage to apply the raised pressure to the power chamber. A pressure reducing device is provided in the power chamber passage, for reducing a fluid pressure in the power chamber passage and applying the reduced pressure to the power chamber, at least while a rate of fluid flow through the power chamber passage is higher than a preset limit.

Abstract: A brake unit for a road vehicle with a hydraulic dual-circuit brake system having two master cylinders, the brake booster and elements for antilock and/or propulsion or slip control in a common housing. A brake booster drive cylinder which can be subjected to the outlet pressure, proportional to the pedal travel, of a brake valve, is arranged between static master cylinders. Coupled to the piston of the drive cylinder is a pivotable rocker, the arms of which are each supported on one of the master cylinder pistons via tappet. Assigned to at least one of the master cylinders is a regulating cylinder having an opposed piston which can be supported on the piston of the master cylinder and which, when subjected on one side to the outlet pressure of the auxiliary pressure source of the brake booster, causes the piston of the master cylinder to be returnable towards its basic position counter to the actuating force exerted on it.

Abstract: A hydraulic force booster for actuating master cylinder pistons in brake systems of automotive vehicles, comprises a lever system including two levers (33,34) pivotably interconnected by way of a journal (35). The second lever, by way of a coupling (45) is in communication with a set element (46) provided at the control piston (13) of a brake valve (9). The coupling (45) comprises a coupling element (53) provided at the second lever (34), and at least one guide surface provided at the set element (46) is connected to the control piston (13) by way of joint (47) and, at the other end, by providing another joint (48), is guided in a substantially co-axial housing bore (49). The coupling element (53) can be formed by a loose roller thereby substantially precluding that transverse forces be exerted on the control piston (13) of the brake valve (9) likely to result in lockings.

Abstract: An input pressure detecting device is arranged in an input side of a pneumatic brake booster, which comprises an elastic member having a given portion which expands when a pressure is applied to the elastic member, a pressure sensor for issuing, upon receiving a pressure, a signal representative of the intensity of the pressure applied thereto, and an axially movable piston intimately disposed between the given portion of the elastic member and the pressure sensor. Upon application of force to the elastic member due to depression of the brake pedal, the elastic member is compressed causing the given portion to expand and thus applying a corresponding but small pressure to the pressure sensor through the piston.

Abstract: A trip throttle valve with a manual exerciser and combination of a hydraulic piston and a biasing force bearing sleeve is provided in place of a piston. The piston is not directly connected to a valve stem and the sleeve is threadably engaged with the valve stem so as to cause relative axial movement between the sleeve and the valve stem when the stem is rotated through the manual exerciser. The hydraulic portion of the valve is provided with a by-pass passage so that the piston is made axially movable toward the sleeve under the pressure which occurs when the by-pass passage for the hydraulic liquid is blocked but the piston is arrested at a certain axial position where the by-pass passage is still blocked and the axial movement of the sleeve is restricted against the piston.

Abstract: A pull-type booster for a vehicle includes a main body having an internal space; a movable body including a head portion and a cylindrical portion formed integrally with the head portion, the head portion being arranged in the internal space and partitioning the internal space into a lower pressure chamber at one side and a control chamber at another side, and the cylindrical portion projecting from the main body at the other side; a through hole formed in the movable body; a pull input rod extending across the low pressure chamber and projecting through a seal member from the main body at the one side; a plunger arranged slidably in the through hole and combined with a head portion of the pull input rod; a valve member arranged in the through hole and operated by the plunger for generating pressure difference between the lower pressure chamber and the control chamber and moving the movable body in the direction of the lower pressure chamber, a power transmission assembly arranged in an opening end portion of

Abstract: An hydraulic booster has a housing provided with a bore, an inlet connected to a source of pressure fluid, and an outlet connected to a reservoir for fluid, a boost piston being advanced in the bore in response to pressurization of a boost chamber, the boost chamber being pressurized under the control of a valve mechanism operative in response to a load applied to an input member. Two connections are provided between the source and the boost chamber, both connections being closed when the booster is inoperative, and when the booster is operated the first connection is opened following initial movement of the input member, and the second connection is opened following initial movement of the boost piston in response to pressurization of the boost chamber. Thus the booster is in a closed center mode when inoperative, but operates in an open center mode. The connections are preferably controlled by valves. The input load may be applied in tension or compression.

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 brake actuation assembly 10 having a master cylinder 12 attached to a stationary wall (14) of a vehicle and a power assist apparatus 16. Linkage 66 connects a movable wall 125 in the power assist apparatus 16 with pistons 64 and 68 in chambers 60 and 62 in the master cylinder 12. A valve 133 responds to an input from an operator to allow a pressure differential to be created across wall 125. The pressure differential moves the wall 125 while at the same time the linkage moves pistons 64 and 68 to pressurize fluid in the master cylinder 12. An adjustment mechanism 82 acts on the piston 68 to control the timing of the interruption of fluid communication between a reservoir 46 and chambers 60 and 62 as a direct function of movement of wall 125.

Abstract: Vehicle power steering gear with a torsion bar whose stiffness is adjusted by an axially shiftable nut that provides a movable gripping point for one end of the torsion bar whose position determines the pliable length of the bar and the steering effort required to steer the vehicle.

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 hydraulic power booster arrangement includes a brake valve which is arranged substantially in parallel to a booster piston and which is operative for controlling the connection from a pressure chamber to a auxiliary pressure source or to an unpressurized return reservoir. To control the movement of the brake valve, there is provided a multipart lever actuation mechanism including a support lever and at least one control lever which are pivotally connected to one another intermediate their respective ends. One end of the support lever is pivotally mounted on a retaining member which is rigidly connectible to the power booster housing. The housing is provided with a mounting hole through which the lever actuation mechanism is adapted to be inserted into the pressure chamber and which is adapted to be closed by the retaining member.

Abstract: A manual actuator which enables manual operation of a valve, damper or other controlled element upon loss of hydraulic pressure in an associated electrohydraulic actuator assembly. The apparatus preferably includes nut segments which are automatically moved into engagement with a coacting threaded shaft upon loss of hydraulic pressure in the electrohydraulic device and which function when so engaged with the shaft to render a manual operating element effective to move the controlled part.

Abstract: A power boost mechanism for converting pilot linear throttle input commands to rotary motion and providing amplification of output torque to an engine fuel control and having an output shaft adapted for connection to an engine power lever assembly. An input member is movable in response to a throttle input command and power boost structure responsive to movement of the input member causes rotation of the output shaft. The mechanism further includes feedback structure associated with the output shaft and responsive to movement thereof for returning said power boost structure to a null position independently of said input member, structure automatically enabling direct operation of the output shaft by said input member when the power boost structure is inoperative, and structure responsive to a malfunction in the engine fuel control causing limited rotation of the output shaft without movement of said input member.

Abstract: A hydraulic brake booster which has an input valve control member acting through a controlled rate spring and through a lever pivoted on the booster housing in the power chamber to move a spool valve in a bore parallel to the power piston so that the input is strictly through the spring. The lever has no connection to the power piston. The control valve is hydraulically unbalanced to a release position and is also urged to the release position by a valve spring. This maintains a proportion between the input force due to the reaction spring, through which input force is applied, and booster pressure. Upon power runout or failure the input and reaction piston overtravels and contacts the output rod to move that rod without moving the power piston.

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: The present invention relates to an improvement in a hydraulic brake booster, and in particular, covers a structure which provides a pressure limiter for the hydraulic brake booster. The booster comprises a housing which defines a pressure chamber and supports a control valve and a piston. During braking the control valve cooperates with an actuator to move relative to the housing so as to communicate pressurized fluid to the pressure chamber and the piston is movable in response to the pressurized fluid within the pressure chamber to effectuate braking. In order to limit the level of pressure of pressurized fluid communicated to the pressure chamber a ring is disposed within the housing in cooperation with the control valve. The ring cooperates with the control valve to define a differential area which is exposed to pressurized fluid to generate a force opposing movement of the control valve so that communication of pressurized fluid to the pressure chamber is limited.

Abstract: A hydraulic power boost apparatus for use with the braking system of an automotive vehicle includes a power piston cooperating with a slide valve to define a plurality of spool valves to regulate the flow of a pressurized fluid therethrough to selectively apply the fluid to boost the force applied to the power piston. A resilient member is positioned within the power piston blind bore to modulate the force transmitted from the slide valve to the power piston. The power piston also includes an annular ridge for engaging a mating annular ridge of the slide valve to limit the travel of the slide valve to prevent the resilient member from being deformed beyond its elastic limit.

Abstract: A hydraulic brake booster (10) includes a spring-balanced control valve (42) communicating pressurized fluid to a pressure chamber (14) in response to an operator input. The magnitude of the fluid pressure communicated to the pressure chamber (14) is a function of the balance of spring forces applied to the control valve (42) by a pair of opposed springs (50, 82). An adjustable assembly (92) engages one of the opposed springs (50, 82) so that the balance of spring forces applied to the control valve (42) may be adjusted to limit to a safe level the maximum fluid pressure communicable to the pressure chamber (14). The adjustable assembly (92) includes a pair of relatively-rotatable members (106, 108) which each define oblique cam surfaces (122, 124) engaging the other member. One of the members (106) engages one of the opposed springs (50, 82). The other member (108) includes an elongate stem (118) terminating in an end (120) external of the booster housing (12).

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 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: A hydraulic booster for a brake system comprising a booster piston, a pressure-control device, an annular piston bearing against the booster piston and a central piston which is movable within limits relative to the annular piston by the brake pedal and actuates the pressure-control device. In this arrangement, the central piston and the annular piston are adapted to be coupled together after the force of a spring is overcome whereupon these two pistons are movable as one. The central piston is permanently subjected to the pressure acting on the booster piston when the brake system is actuated.

Abstract: A power boost mechanism for converting pilot linear throttle input commands to rotary motion and providing amplification of output torque to an engine fuel control and having an output shaft adapted for connection to an engine power lever assembly. An input member is movable in response to a throttle input command and power boost structure responsive to movement of the input member causes rotation of the output shaft. The mechanism further includes feedback structure associated with the output shaft and responsive to movement thereof for returning said power boost structure to a null position independently of said input member, structure automatically enabling direct operation of the output shaft by said input member when the power boost structure is inoperative, and structure responsive to a malfunction in the engine fuel control causing limited rotation of the output shaft without movement of said input member.

Abstract: The present invention is a gain valve for a hydraulic booster which allows transition from a manual braking mode to a power assist braking mode without the control called for in the manual mode immediately applied when the power assist function begins to operate. This is accomplished by a bypass passage through the gain valve piston which prevents a pressure increase in the hydraulic booster for power assisted braking. The bypass passage automatically opens and resets in response to system pressures.

Abstract: A hydraulic brake booster includes a housing substantially defining a pressure chamber and movably supporting a control valve and a piston. An input assembly extends into the pressure chamber and cooperates with the control valve to communicate fluid pressure to the pressure chamber. The input assembly is pivotal relative to the piston to a first position wherein fluid pressure communicated to the pressure chamber acts against the piston to move the same while the input assembly remains substantially stationary in the first position. In particular, the input assembly includes a lever with a slot for receiving a portion of the piston. When the lever is pivoted to the first position, the piston portion moves within the slot from one end of the slot to the other end. A pair of springs extend between the housing and the piston and lever, respectively, to bias the piston and lever to a rest position abutting the housing.

Abstract: The present invention is an improved hydraulic booster which allows transition from a manual braking mode to a power assist braking mode without the control called for in the manual mode immediately applied when the power assist function begins to operate. This is accomplished by opening a path through a chamber in the gain valve and a bypass passage to prevent a sudden pressure buildup in the hydraulic booster at the gain valve when the hydraulic booster is operated in a manual mode and the fluid pumping means is suddenly started.

Abstract: A servo-supported gear changing apparatus for mechanical gearboxes. A rotatably and axially displaceable gear selector shaft in a gear selector housing is axially displaced, during a selecting step, to a preselected engagement position, and is turned to engage or disengage the appropriate gear by at least one gear selector mounted on the shaft. At least one torque-transmitting connection between the shaft and its lever has limited play in both directions, allowing in the initial engagement or disengagement stage a relative movement in the turning direction. A control valve then triggers a pressure-operated servo cylinder to perform the major gear changing work.

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 vehicle brake system in which an output member is axially displaceable by the application of differential fluid pressure, under the control of a valve operable by an input member, across a movable internal wall which divides a housing of the booster into a pair of fluid chambers. Displacement of the movable wall is communicated to the output member via a lever mechanism providing a mechanical advantage between said movable wall and the output member. The lever mechanism comprises first and second levers. The second lever is pivotable relative to the input and output members at respective pivot points.

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: The booster is installed downstream of a vehicle's power steering gear. The booster has a power piston and a valve seat piston reciprocably mounted in a bore of the booster housing. Hydraulic inlet pressure is introduced into the housing bore between these pistons and flows through a normally open poppet valve, which acts as a booster control valve. Movement of the booster input push rod restricts hydraulic fluid flow through the control valve and causes pressure to be built up in the power chamber between the pistons. The pressure acts on the power piston to move the booster output member. The pressure also holds the valve seat piston in position against the bore and wall so that it does not move during normal power boost operation. In the power mode brake pedal travel can be very low, permitting a high brake pedal ratio for the no-power operating mode.

Abstract: The booster is installed downstream of a vehicle's power steering gear. The booster has a power piston and a valve seat piston assembly reciprocably mounted in a bore of the booster housing. The valve seat piston assembly includes two nested control pistons separated by a rubber cushion member which permits limited relative control piston movements. Hydraulic inlet pressure is introduced into the housing bore between these pistons and flows through a normally open poppet valve, which acts as a booster control valve. Movement of the booster input push rod restricts hydraulic fluid flow through the control valve and causes pressure to be built up in the power chamber between the power piston and the valve seat piston assembly. The pressure acts on the power piston to move the booster output member. The pressure also holds one of the control pistons of the valve seat piston assembly in position against the bore end wall so that it does not move during normal power boost operation.

Abstract: A steering mechanism with time derivation wherein a servo member dependent upon an angular velocity of a steering wheel is connected in the manner of a gear system by means of a summing gear mechanism with a servo member dependent on an angle of the steering wheel turn and also with a servo member dependent on an angle of the wheel turn of steered vehicle wheels. A gear element of the summing gear mechanism pertaining to the servo member dependent on the angular velocity is supported toward a housing by way of a resilient support. The servo member dependent on the angular velocity is positively turned off with respect to its action on the summing gear mechanism if the steering wheel angle exceeds a specific limiting angle.

Abstract: The hydraulic brake booster power piston has a rectangular cross section seal groove containing a rectangular cross section lathe cut seal having a greater inner diameter than the groove as well as a greater outer diameter. Radial clearance is provided between the piston and the cylinder wall. The groove has one or more holes at its inner diameter opening axially into the booster power pressure chamber. The seal is also axially thinner than the groove. Power pressure holds the seal in sealing relation with the cylinder wall and the piston. When fluid must flow from the exhaust chamber side of the piston to the power chamber side (e.g. during manual no-power operation) the seal moves to the other groove side, allowing flow radially inward in the groove and past the seal inner periphery through the hole or holes to the power chamber.

Abstract: A hydraulic brake booster for a vehicle brake system which has a control valve, actuatable via an excursion-limiting spring, which directs the flow of pressure medium from a supply source as an auxiliary force means. The excursion-limiting spring disposed subsequent to the brake pedal provides for sensitive response on the part of the control valve. In event the auxiliary force fails, the excursion-limiting spring is made ineffective so that pedal travel does not occur without being utilized. A shut-off mechanism is included to make the excursion-limiting spring ineffective has a shut-off member dependent on brake actuation and to which a motion pulse dependent on brake actuation can be imparted in the area of its outset position. In this manner, the shut-off mechanism is used during each occurrence of braking and thus cannot seize as a result of corrosion.

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: The device comprises a master piston and cylinder assembly the piston of which is interconnected with the piston of an assisting jack by means of a connecting element on which is articulated the brake lever. The end of the brake lever remote from the brake pedal acts on a distributor adapted to feed the assisting jack with assisting hydraulic pressure so that when a force is applied to the brake pedal and thereby to the master piston via the connecting element, the distributor directs hydraulic fluid under pressure to the assisting jack, the piston of which then applies an assisting force to the connecting element.In the improvement of the invention, an abutment surface is provided for the brake lever located between the articulation point of the lever and its point of contact with the distributor so as to increase the mechanical advantage of the brake lever in the event of failure of the assisting hydraulic system.

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 power steering device includes a housing which journals coaxial input and output shafts. Drivingly connected to the input shaft is an eccentric which rotatably carries a gear wheel. The gear wheel is prevented from rotating in the housing so that it gyrates when the input shaft rotates. An internally toothed ring meshes with the gear wheel and is drivingly connected to the output shaft. The internally toothed ring defines a greater number of gear teeth than does the gear wheel so that gyration of the gear wheel incident to the rotation of the input shaft drives the output shaft via the internally toothed ring. A valve device is responsive to rotation of the input shaft relative to the output shaft to control fluid flow to and from a fluid motor. The fluid motor is coaxial with and drivingly connected to the output shaft so as to increase the torque derivable from the output shaft incident to rotation of the input shaft.

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: Hydraulic servo steering gear having a cylindrical, double-acting working piston connected to a steering shaft by a rack-and-sector gear connection, especially for motor vehicles comprises a piston-and-sleeve type control mechanism arranged in the working piston. The cylindrical outer surface of the sleeve of the control mechanism is fitted loosely, with a radial gap, in the seat formed therefor in the double-acting working piston. The control sleeve is secured against axial and angular displacement.

Abstract: A servo-assisted hydraulic master cylinder has a variable ratio effect so that brake fluid is initially displaced to the brakes at a high rate with respect to driver pedal movement and then at a low rate when an appropriate pressure has developed. A stepped piston assembly comprising a first piston slidable in a second piston defines a first chamber which is directly connected to the brakes and a second chamber in which a variable pressure is developed. The first piston is operated directly by the pedal through the servo valve and is subject only to brake pressure in the first chamber so that brake pressure is proportional to driver effort during normal operation. The second piston is operated by the servo diaphragm through the servo valve housing.

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.

Abstract: A hydraulic brake booster having a mechanical ratio changing mechanism between the booster input rod and one of the booster valve control members. The mechanism includes reaction levers pivotally mounted on the input valve control member and on a support member so that in normal booster operation the levers operate to move the input valve control member at a faster rate than the input rod, while the levers pivot to permit direct mechanical transmission of force from the input rod through the booster when no power or insufficient power is available to operate the booster.

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

Abstract: A brake booster includes a housing with an inner wall defining a pair of pressure chambers. A passage in the inner wall communicates the pressure chambers with each other and an input member is slidably disposed in one of the pressure chambers and an output member is slidably disposed in the other pressure chamber. A resilient member extends between the inner wall and the input member and substantially defines a variable orifice to control fluid communication between an inlet and a return. The return is disposed within the inner wall and the resilient member comprises a coil spring which permits fluid communication between the coils. When the input member is moved the coil spring is contracted to decrease the spacing between the coils, thereby restricting fluid communication between the inlet and the return. Consequently, increased fluid pressure within the other chamber urges the output member to move thereby actuating braking.

Abstract: A power steering gear mechanism is disclosed having conventional elements such as a double acting cylinder in a housing, a piston with a gear rack geared to a gear sector, and threaded bore in the piston having a worm shaft, wherein a steering shaft operates a rotary valve spool with which it is integral, in rotation relative a fixed valve sleeve carried by the worm shaft and wherein a torque rod connects the worm shaft to the steering spindle and passes through the worm shaft. The novelty of the invention resides in hydraulic circuitry and in the placement of a pin carried by the worm shaft and passing through a bore in the body of the valve spool just beyond one end of the channelled flow control area, the steering shaft extending from the other end of the valve spool. The pin effects rotation of the worm shaft by engaging the side of the bore through the valve spool body during twisting of the torque rod to effect piston movement.

Abstract: A vehicle brake booster and master cylinder assembly has a vacuum suspended booster section which is controlled by movement of the vehicle brake pedal. A hydraulic booster section is in series with the vacuum suspended booster section, and a master cylinder unit is in series with the hydraulic booster section. The assembly is so arranged that in normal operation the vehicle operator obtains boosted brake actuating pressures by operation of the vacuum suspended booster which acts through the hydraulic booster mechanism without operating the hydraulic booster. When greater brake actuating pressures are required, as indicated by increased brake pedal force exerted by the operator, the vacuum booster reaches its limit or runout condition and the hydraulic booster is operated so as to continue the increase in master cylinder output pressure.