Abstract: A safety hydraulic brake system for automotive vehicles which includes a control cylinder having an inlet connected to a hydraulic pressure source, and first and second outlets connected to brake cylinders at front and rear wheels, respectively. A valve is located at each outlet and normally allows pressurization of the front and rear wheel cylinders upon actuation of the hydraulic pressure source. First and second pistons, each having a by-pass valve, are slidable in the control cylinder. The pistons and by-pass valves are operable, when there is a loss of brake pressure in the lines to one set of brake cylinders, to effect closing of the control cylinder valve to that brake cylinder set. This allows brake pressure to be maintained at the other set of wheel cylinders and the vehicle to be safely braked.

Abstract: A closed-center brake system and brake valve are disclosed. A closed-center variable displacement pressure compensated pump delivers fluid pressure to a valve inlet which carries a normally closed check valve. When a valve operating rod is partially withdrawn from the valve, the check valve opens to admit fluid to a valve chamber; fluid pressure and flow are directed from the chamber to ports leading to a vehicle left-hand brake and a vehicle right-hand brake. Should fluid pressure be lost in upstream portions of the system, further pulling action on the valve rod will collapse the chamber and manually deliver pressurized fluid to the brakes. Another brake valve outlet port, located just downstream of the inlet check valve, provides for delivery of pressure compensated fluid back to the pump to cause the pump to operate with desired characteristics.

Abstract: In the case of pump failure a spool valve instantly connects a pressurized fluid accumulator with the servo motor which assistingly activates the master cylinder and isolates a power steering mechanism fluidly connected to the servo motor so that only the power brake is temporarily operable but with stepwise decreasing effectiveness.

Abstract: A master cylinder for a two-circuit brake system which includes anti-skid control has two separate chambers and pistons. The main control piston is surrounded by an auxiliary piston which it engages after a predetermined amount of travel. The auxiliary piston has an extension which holds the brake control valve and which is opened by the control piston during its travel. Furthermore, the second circuit cylinder includes a pressure sensor which can activate a warning when the piston travel is not in a predetermined relation to the applied fluid pressure.

Abstract: A hydraulic brake booster includes a housing defining a pressure chamber and an inlet port communicating pressurized fluid to an accumulator and the pressure chamber. The housing includes a bore which slidably receives a charging valve and sealingly receives a check valve. The charging valve sealingly engages the housing bore via a sealing ring in one position and is pressure responsive to move toward a second position abutting the check valve to open communication between the inlet port and the accumulator. A stem is slidably carried in a passage in the check valve and the stem is received in a slot in the charging valve. An operator actuator is engageable with the stem to unseat one end of the stem from the check valve so that pressurized fluid from the accumulator is communicated to the pressure chamber.

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

Abstract: A fluid motor having a housing with a stepped bore for retaining a first piston and a second piston. A sleeve is located in the stepped bore to permit the first piston and the second piston to be of substantially the same diameter. A plug attached to the housing holds the sleeve in the stepped bore. A spring attached to the sleeve holds the first piston against a stop. The spring acts on the sleeve to create a gap with a shoulder in the stepped bore. The second piston which is connected to the first piston through a linkage mechanism carries a concentric shuttle piston. The shuttle piston is subjected to a first hydraulic pressure created by the first piston and to a second hydraulic pressure created by the second piston. An indicator is connected to the shuttle piston and remains inactive when the first and second hydraulic pressures are substantially equal.

Abstract: A combined brake and steering system for a vehicle having hydraulic braking and hydraulic steering. A single pump is utilized to supply both the brakes and steering. Two priority valves are arranged to assure that the brakes take precedence and receive an approximately constant flow of hydraulic fluid subject to a maximum pressure. The steering mechanism also normally receives a constant flow, subject to a maximum pressure which usually is different from the other maximum pressure.

Abstract: A hydraulic brake booster of the type utilizing pressurized fluid supplied to a hydraulic power steering device, wherein a flow regulating valve is adapted to rapidly increase the pressure in a power chamber of the booster in response to actuation of the booster and another flow regulating valve is adapted to ensure supply of the pressurized fluid to the power steering device, and wherein an accumulator is adapted to surely operate the booster even when pressure supply to the power chamber from the fluid pressure source is accidentally blocked or stopped.

Abstract: A shifting apparatus for the indirect changing of the mechanical brake pedal transmission ratio in case of failure of the servo-assist of a motor vehicle brake force booster system, in which the shifting apparatus can be installed at any suitable place of the motor vehicle as well as in the lines extending between the master brake cylinder and the wheel cylinders; the control piston which is arranged in the shifting apparatus is actuated by the medium put under pressure by the pump of the servo-installation, and undertakes the shifting control of the pressure medium coming from the master cylinder to attain a shifting action in case of failure of the servo-installation.

Abstract: A brake booster for use in a braking system having a control valve which is responsive to a hydraulic output force created by manually moving a piston in a bore of a master cylinder. The hydraulic output force actuates the control valve which proportionally directs a portion of the fluid output of a pump which supplies a power steering gear with hydraulic fluid, into the bore. This portion of the output of the pump acts on the piston and provides an auxiliary force for moving the piston through which the hydraulic output force is created. When the hydraulic output force of the brake booster reaches a predetermined value, the control valve engages a stop member to limit the diversion of the fluid output from the pump and thereby assure that a minimal quantity of the fluid output is continually available to operate the power steering gear.

Abstract: A hydraulic brake booster provides two independent accumulators for assisting a brake application when insufficient pressure is communicated to the hydraulic brake booster for braking. The first accumulator is connected to the hydraulic brake booster housing, and the second accumulator is remotely disposed to the housing with a conduit forming a connection therebetween. A spool valve, slidably mounted in the housing, is engageable with a pair of check valves to communicate the first and second accumulators with a pressure chamber within the housing. A pair of bores within the housing receive the check valves and a unitary relief and charging valve is slidably carried in each bore for communicating an inlet port with each accumulator.

Abstract: The invention relates to a hydraulic servomotor comprising a housing provided with a bore slidably receiving two pistons separating an actuating chamber from an utilization chamber, said pistons including an annular outer piston and an inner piston received within the annular piston. Releasable coupling means are provided between both pistons to permit said pistons to move in unison when high pressure fluid is available in the actuating chamber and to permit the inner piston to be moved alone by the push rod in the event of a high pressure failure in the actuating chamber. The motion of the outer piston towards the interior of the actuating chamber is limited by an abutment fixed to the housing.

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

Abstract: There is provided an improved dual side-by-side master cylinder having parallel pistons, one for each of two hydraulic sub-systems, and an actuator to move the pistons from a single applied force, e.g., a brake pedal, characterized by an improved structure for the actuator and its coacting rocking beam member for equalizing pressures in the two hydraulic sub-systems and for providing for takeover for direct transmission of force to one piston in the event of failure in the other sub-system.

Abstract: A hydraulic brake booster for use with an open center-type power steering system includes, upon the application of the vehicle brakes, a relief valve piston mechanism for setting the fluid pressure greater than the fluid pressure being previously circulated through the power steering system and a spool valve assembly for selectively admitting the high fluid pressure to a power piston device for the brakes, so that the load upon a pump, under non-application conditions of the brakes, will be reduced whereby it will be easy to accumulate the fluid pressure for the brakes in case of an emergency due to the fact that the fluid pressure set by the relief valve piston can be greater than the pressure required for charging gas within the accumulator.

Abstract: A safety brake pedal for power-assisted brake systems of motor vehicles of the type having a source of fluid under pressure includes a member adapted to transmit the brake control effort and associated with and normally locked to the brake pedal by an assembly responsive to the fluid from the source. The interlocking action is removed in case of accidental drop or failure in the fluid pressure, the extra free stroke of the brake pedal thus permitted being utilized for actuating a safety brake.

Abstract: An oil-hydraulic servo-motor, usable with an automotive brake, including a control piston slidably extending through the rear end wall of a power cylinder in aligned opposite relation to an output piston therein and forming together with the cylinder end wall a spool-type control valve which is operable to energize and de-energize the power cylinder. The control piston is axially movable normally within definite limits under the operator's input, and abutment means provided to limit the extent of advancing movement of the control piston is rendered inoperable automatically upon failure of an associated oil pressure circuitry to enable the control piston to drive the output piston directly under the operator's input. The oil pressure circuitry may be formed in two independently operable systems. Major features include simplicity of the valving mechansim and hence of the entire structure of the servo-motor and a highly improved reliability in operation.