Abstract: Apparatus for indicating the condition of hand brakes on railway cars and for applying and releasing railway car parking or hand brakes automatically in response to predetermined conditions including movement of a train, wayside conditioning apparatus, wayside operating mechanism, a signal controlled by an operator and performance of predetermined railway operating procedures, such as completion of an air brake test procedure. The apparatus may respond to mechanical, electrical and electronic signals and may operate on pneumatic or electric power provided from the service air brake system of a train or from a source of power outside of such air brake system.

Abstract: The instant invention is a positive shutoff valve for use on emergency vehicles so as to maintain air within a reservoir tank allowing immediate movement of an emergency vehicle upon start up. The shutoff valve is operated by a switch located in the operator's compartment of the emergency vehicle providing movement of a solenoid located in the shutoff valve which is biased in a normally closed position. A manual bypass lever is provided should the electric solenoid fail to operate correctly. The shutoff valve positively maintains air within the reservoir tank and is monitored by a low pressure switch and alarm sensor which will indicate low air pressure in the reservoir tank even when the vehicle is in an off position.

Abstract: A full-function brake valve for a tandem trailer is contained within a single housing and provides a boost to the control air signal arriving at the full-function valve so that the control air signal can be delivered to a second trailer full-function valve without degradation of the control air signal. The signal boost function is provided by an aperture in the piston of the relay valve that connects the control air inlet to the supply air, to cause the supply air pressure to boost the control air signal.

Abstract: A device for applying the brake of a towed vehicle when towed by a towing vehicle equipped with an air brake system having a power brake operator operative to supply operating air under pressure to apply a brake on the towing vehicle and also having a reservoir of operating air under pressure. The device is connected to the brake pedal of the towed vehicle. It comprises a first piston-cylinder assembly with a spring for urging the piston therein to an advanced position, and a second piston-cylinder assembly having a spring urging the piston therein to a retracted position. The brake on the towed vehicle is applied only when one of the pistons is advanced. An air line supplies air from the reservoir to the first piston-cylinder assembly to urge the piston to a retracted position against the action of the spring.

Abstract: A work brake system applies a reduced air pressure service brake application as a work brake to hold a heavy duty vehicle in place without actuation of conventional spring brakes during frequent start-and-stop operations of the vehicle, such as in refuse collection. The work brake system includes fail safe features to prevent vehicle roll in the event of loss of air pressure, by providing separate primary and secondary sources of pressurized air, and by automatically diverting to application of spring brakes in the event of primary pressure or signal loss.

Abstract: A full function brake valve for a semi-trailer is contained within a single housing and provides ports for receiving supply air and control air, and for delivering and receiving air from reservoirs, service brakes and spring brakes, and delivering air to an exhaust. The internal valves include a pressure protection valve which communicates with a first check valve and a quick release valve to pressurize spring brake chambers, and a reservoir check valve and a relay valve to respectively pressurize a reservoir and to deliver supply air to service brakes. An orifice preferably provided in a second check valve permits partial air flow to the spring brakes to release the spring brakes for towing the vehicle.

Abstract: A full function skid control valve assembly for use in an air brake system which provides for brake control utilizing a compact single assembly. The system provides for the maintenance of certain minimum operating pressures so that, when the air pressure within the vehicle brake system falls below predetermined levels, the valve assembly automatically partially or entirely exhausts the air pressure sometimes causing the spring parking brakes to engage. Once the air pressure within the brake system returns to predetermined levels, the valve assembly will allow a reservoir to be charged and the spring brakes to be deactuated. During operation, the assembly provides control of the service brakes while preventing undesired skid conditions.

Abstract: A parking brake system is provided which includes a dual solenoid operated valve located in series with the emergency brake control valve of a hydraulically operated brake system. The dual solenoid valve is operable to either one of two mechanical detent positions so that positioning of the valve is retained in the event of loss of power. The dual solenoid valve is controlled by the vehicle operator from the transmission console and removes fluid pressure from the brakes when actuated to a PARK position. An electronic control unit is provided for sensing the speed of the vehicle and the pressure in the hydraulic line to the brakes and provides a PARK enabling signal when the vehicle speed is below a predetermined amount. When a gear is selected at the console the dual solenoid valve is actuated to a position permitting fluid pressure to be applied to the brakes and effectively returns control of the brakes to the emergency brake control device.

Abstract: Control valve assemblies for regulating the parking/emergency spring brakes of a tractor trailer air brake system which include valve components for insuring that the spring brakes are not released until pressurization of the system's service reservoir is achieved and which components are operable to exhaust the spring brakes to atmosphere upon the failure of the supply pressures within the system to thereby automatically apply the spring brakes. In one embodiment, the valve components permit pressure to be supplied to release the spring brakes under circumstances when it is not possible to pressurize the service reservoir.

Abstract: The hydraulic actuation system (10) utilizes efficiently stored hydraulic pressure to effect a higher final pressure in the system (10) for a parking brake application. The system includes a pump (12) which communicates separately with accumulators or pressure storage mechanisms (20, 30) isolated from one another. A first accumulator (20) communicates with a first three-position apply and release valve mechanism (40) that can communicate via an apply hydraulic line (26) with a second two-position apply valve mechanism (50). The second accumulator (30) communicates with the second apply valve mechanism (50). The second apply valve mechanism (50) communicates the apply hydraulic line (26) with apply lines (55, 63, 73) and at least one brake (60, 70) that is hydraulically actuated for a parking brake application. The brake (60, 70) includes a release hydraulic line (62, 72, 49) which communicates with the first apply and release valve mechanism (40).

Abstract: A railway brake actuator which provides both service and parking braking comprises a cylinder having an operating cavity. A piston assembly in the operating cavity has a stepped bore forming second and third cavities and is extended by hydraulic pressure and retracted by a spring to apply and release the service brake. Hydraulic pressure extends a hollow parking brake piston from the second cavity to extend the piston assembly and apply the parking brake. A one-way clutch comprising ramps and rollers locks the piston in parking brake applied position. Hydraulic pressure disables the clutch to enable spring retraction of the parking brake piston and the piston assembly to release the parking brake. A gripper ring on the piston assembly operates between cylinder abutments to limit piston assembly retraction to provide slack, and enables slippage on the piston assembly on extension to adjust for brake wear.

Abstract: A two-stage brake control valve has a larger first stage and a smaller second stage. First stage operates to fill a brake. Then, after a transition phase only the second stage is used to supply the working pressure. A check valve is between the first stage pressure chamber a sump. The check valve opens if the pressure in the first stage pressure chamber exceeds a predetermined value. To minimize the operating force of the valve and to avoid a sudden change of the valve working pressure during the changing phase, the closing force of the check valve is controlled as a function of the valve working pressure. The valve working pressure acts on a valve spool which influences the closing force of the check valve in the way that the closing force decreases with increasing working pressure.

Abstract: A brake release apparatus for a vehicle equipped with a spring-applied hydraulically-released brake system. The apparatus includes a tow hook attached to the vehicle and operably connected to a hydraulic cylinder so that a towing force on the tow hook actuates the hydraulic cylinder. The hydraulic cylinder is connected to transmit a hydraulic pressure to the vehicle brakes, releasing the brakes to permit towing. A spring returns the tow hook to its original position when the towing force is removed, thereby permitting the spring-activated brakes to be reapplied.

Abstract: Within a single envelope or housing, this full-function valve integrates all of the emergency and service requirements of a tandem axle air brake system for heavy duty truck semi-trailers, thereby decreasing complexity and cost and enhancing safety, reliability and operating capability while also satisfying applicable Federal Regulations. The housing encloses a spring brake valve module, a relay valve module and a biased one-way pressure protection valve, all interconnected to meet operating requirements, while preventing non-intentional spring brake engagement, foreclosing trailer movement without adequate service brake capability and optionally providing anti-compounding protection.

Abstract: An air brake control system for use in truck trailers, including tandem trailers, having at each axle compressed-air spring brakes and service brakes with each trailer being coupled to receive compressed air through an emergency (supply) gladhand and to receive service brake signals through a service (control) gladhand and which includes an integrated brake valve system for each trailer within a common valve housing.

Abstract: An electro-pneumatic braking system includes a tandem brake actuator including a service brake actuating section and an emergency/parking spring actuated section. Hold-off pressure is communicated to the emergency/parking section through a three-way solenoid valve from a pressure reservoir, and communication to the service actuator is controlled by an electro-pneumatic modulator. Service pressure is taken both from the branch of the conduit communicating with the air reservoir, and from the hold-off pressure in the emergency/parking reservoir. Accordingly, only a single line communicates fluid pressure from the reservoir to the brake, and service brake response time is improved because the hold-off pressure and the emergency/parking section of the actuator is used as a small reservoir immediately adjacent the service actuator.

Abstract: A brake release apparatus for a vehicle equipped with a spring-applied hydraulically-released brake system. The apparatus includes a tow hook attached to the vehicle and operably connected to a hydraulic cylinder so that a towing force on the tow hook actuates the hydraulic cylinder. The hydraulic cylinder is connected to transmit a hydraulic pressure to the vehicle brakes, releasing the brakes to permit towing. A spring returns the tow hook to its original position when the towing force is removed, thereby permitting the spring-activated brakes to be reapplied.

Abstract: An isolation valve device for a hydraulic brake system of a railway vehicle including passageways via which hydraulic pressure communication is established between a pressure controller and the brake units of each truck of a railway vehicle, and diaphragm type flow control valves adapted to interrupt hydraulic pressure communication in a respective one of the passageways leading to the different truck brake units, when a pressure differential occurs therebetween, due to a ruptured brake line at one of the trucks, for example, causing a hydraulic fluid leak thereat.

Abstract: A hydraulic wheel braking system for a vehicle includes wet disc wheel brakes that are applied by a single spring-activated piston within each brake housing. Each piston is selectively and variably disengaged from the brake discs by variable hydraulic pressure acting against the piston in opposition to spring pressure to enable controlled wheel rotation. During vehicle operation, brake fluid pressure at the pistons is controlled by a foot pedal-operated brake valve. A manually-operated parking and control valve assembly can selectively disable the brake valve and relieve hydraulic pressure at the pistons to spring-apply the pistons to the discs. The assembly acts to automatically spring-apply the pistons to the discs upon a loss of brake or transmission clutch fluid pressure.

Abstract: An emergency compressed-air brake for automobiles has the advantage to combine integrally the emergency braking, the service braking and the parking braking, which can be widely used in various road vehicles. The combined braking air-chamber involved is simple in construction. The thrust of braking includes two parts, the air pressure thrust and the spring thrust, with the resultant force of the two thrusts as a service braking thrust, with the spring thrust as a parking and emergency braking thrust. Since the spring force throughout joins in the braking, the braking gets more smoothness and is able to anti-locking.

Abstract: An improvement in a conventional air-operated diaphragm spring brake is provided by a guide (100) being disposed in registry with an aperture (26) in a service brake housing (16). A push-rod (10) extends from a diaphragm (58) within the housing (12) through the bushing (102) to pivotably connect to a slack adjuster (6). The bushing (102) serves to maintain the push-rod (10) at a preselected angle relative to the slack adjuster (6) when the push-rod is in the inoperative position.

Abstract: A friction brake mechanism having a pair of front brake assemblies and a pair of rear brake assemblies receives pressurized fluid at the same time and at the same pressure from a hydraulic control apparatus. Each of the brake assemblies has a brake piston movable in a chamber between a holding position and a releasing position and a plurality of brake plates and a plurality of brake disks interleaved with the brake plates. A first spring system is associated with the pair of front brake assemblies and a second spring system is associated with the rear brake assemblies. The first spring system provides a different force than the second spring system to cause the rear brake assemblies to be engaged a predetermined period of time ahead of the pair of front brake assemblies without any design change in the hydraulic control apparatus.

Abstract: A hydraulic control valve for controlling the parking brakes of a vehicle hydraulic braking system having mechanically applied parking brakes which are released by hydraulic pressure includes a housing having a mechanically actuated control valve and a diverter assembly. When the vehicle is parked, the parking brakes are vented to reservoir and fluid from the vehicle hydraulic pump is communicated directly from the inlet of the valve to the return or drain port of the valve. When the brakes are released, communication between the spring brakes and reservoir pressure is cut off, and fluid communicated into the inlet is diverted to the diverter assembly, which builds pressure to a predetermined level which is communicated to the vehicle parking brakes to release the latter. When the predetermined pressure level is attained, the diverter assembly automatically opens to permit fluid to bypass the diverter assembly back to the return or drain port.

Abstract: A servo-brake-auto-modulator of the kind for use in a trailer provided with a pneumatic braking system is modified so as to enable also the achievement of the functions of an anti-overload valve. To that end a discharge passage (26) which communicates with the atmosphere is formed in an inlet chamber (22) of the body (51) of the servo-brake-auto-modulator (20) in such a position that a control member (47) in one of its working positions, causes a control chamber (33) to be connected to said discharge passage (26), preventing overloading of the parking-brake members (6).

Abstract: A hydraulic wheel braking system for a vehicle includes wet disc wheel brakes that are applied by a single spring-activated piston within each brake housing. Each piston is selectively and variably disengaged from the brake discs by variable hydraulic pressure acting against the piston in opposition to spring pressure to enable controlled wheel rotation. During vehicle operation, brake fluid pressure at the pistons is controlled by a foot pedal-operated brake valve. A manually-operated parking and control valve assembly can selectively disable the brake valve and relieve hydraulic pressure at the pistons to spring-apply the pistons to the discs. The assembly acts to automatically spring-apply the pistons to the discs uopn a loss of brake or transmission clutch fluid pressure.

Abstract: The brake activation apparatus comprises first and second brake devices capable of being selectively applied, a shifting mechanism for selectively applying either the first or second brake device and not the other, a mechanism for overriding the shifting mechanism for applying both of the first and second brake devices, and a mechanism for releasing the override during both normal and manual operation. The apparatus is useful in a power drive unit comprising a carrier having first and second planetary gears rotatably mounted on the carrier, first and second rotatably mounted sun gears in meshing engagement with the respective planetary gears, the sun gears each having a drive output portion for driving respective devices and a braking portion for cooperation with the first and second brake devices to control the output of the power drive unit by selectively braking the respective sun gears.

Abstract: A brake is disclosed for the end of a shaft such as a motor shaft including a bowl-shaped housing secured to a bowl-shaped cylinder and sandwiching a pressure plate therebetween. A torque plate is reciprocally mounted and rotatably related to the housing by dowel pins which are reciprocally received in sleeve bearings and is biased by springs sandwiched between the torque plate and the housing and retained on spring pins. The torque plate includes circumferentially spaced integral lugs which extend through openings formed in the pressure plate and abut with a push plate of a reciprocal piston. A drive disc which is rotatably related but axially movable relative to the shaft to be braked is located radially inwardly of the lugs and is sandwiched between the torque plate and the pressure plate. The piston is also bowl-shaped and includes a circular plate terminating in an axially extending flange which is reciprocally received in an axially extending flange of the cylinder to define a pressure chamber.

Abstract: A safety system for hydraulic brakes in a train brake system wherein a spring biased spool valve controls delivery from a hydraulic fluid source to at least two sets of spring applied hydraulic brake actuators and wherein said spool valve is also biased by the fluid pressure delivered to said two sets of brake actuators and upon a rupture in a brake line delivering fluid to one brake actuator, which causes a lowering of a fluid pressure force on the spool valve, causes the spool valve to shut off the delivery of fluid to the ruptured line to allow the spring applied hydraulic brake actuator to engage the applied brake.

Abstract: A control valve for a fluid pressure braking system includes a housing which receives a pair of identical plungers and corresponding springs acting on the plunger which activate automatically at different trip pressures. The differential trip pressures are attained by providing different valve seating areas on the housing and spring cavities of different depths.

Abstract: An electrically-controlled fluid pressure responsive brake system, in which a solenoid valve is installed between a manual brake valve and a parking brake. The parking brake is equipped with a spring actuator. The solenoid valve can be positioned by an electronic system into an open position only when an ignition switch has been turned on and the brake system has been successfully tested by the electronic system. The test can be initiated by pressing the brake pedal all the way to the floor. The solenoid valve allows the release of the parking brake only if the brake system is intact.

Abstract: An anti-skid brake control system includes a fluid distributor member with first and second chambers, each of which is associated with a respective one-way valve for connecting it to the source and for preventing the propagation of fluid pressure from the source and for preventing the propagation of fluid pressure from the source to the respective chamber. A piston is sealingly slidable in each chamber and divides the chamber into a first volume, which communicates with the one-way valve associated with the respective chamber, and a second volume. The first volume of the first chamber communicates with the second volume of the second chamber. Each piston has an actuator for keeping the adjacent one-way valve in an open position when the piston is moved toward the one-way valve. An actuator selectively applies a force to the piston in the first chamber to move the piston.

Abstract: A plunger system in a brake line between a master brake cylinder and a wheel brake cylinder of a vehicle, for modulating a brake pressure in the event of a sensor-detected danger of wheel locking or wheel spinning. The plunger system has a plunger that is axially displaceable in a housing. At one end, the plunger engages a variable pressure chamber toward the master brake cylinder and at the other it engages a variable pressure chamber toward the wheel brake cylinder. It has an axial bore, through which a rod passes, between the two pressure chambers, and this bore can be closed on opposite ends if there is a danger of wheel locking or if wheel spinning occurs. The closure of the axial bore is effected by an axial motion of the plunger, which takes place if the wheels lock, on the one hand, and if they spin, on the other.

Abstract: A hydraulically-actuated brake system for off-road, heavy vehicles that includes separate accumulators for braking the front and rear brakes and brake valves that are both manual and pilot actuated for controlling the flow of hydraulic fluid from the accumulators to the brakes. Also included are valves for comparing the pressure in the front and rear accumulators so that, should one of the systems become low, the brakes are immediately set. Also included is a manual valve for overriding the brake valves in the event that a malfunction occurs in one of the brake valves.

Abstract: A vehicle brake system includes a check valve having an input port coupled to a fluid pump outlet and an output port coupled to hydraulically deactuated spring brakes through brake lines. A pilot check valve has a pilot port, an inlet port coupled to the input port of the check valve and a return port coupled to the fluid reservoir. The pilot port is coupled to the output port of the check valve so the pilot check valve opens only when the output port is pressurized. This allows hydraulic fluid to flow from the pump, through the pilot check valve and to the reservoir. To set the brakes when stopped or in emergency situations the operator actuates a valve which dumps the fluid in the brake lines into the reservoir. A second pilot check valve has its pilot port connected to a brake pedal actuated master cyinder, its inlet connected to the brake line and its outlet connected to the reservoir.

Abstract: A protection valve device for a spring parking brake control system has a pipe bracket for connection in a normally pressurized brake pipe, the pipe bracket having connected thereto a protection valve, a charging reset valve and a charging check valve. The protection valve has a chamber at one side of a piston normally pressurized by pressure at a spring parking brake cylinder port and monitors the spring parking brake cylinder pressure to vent fluid from the brake pipe to automatically cause an emergency brake application if such pressure indicates a spring parking brake is applied. The charging reset valve prevents the venting of brake pipe fluid during charging of the brake pipe and spring parking brake system.

Abstract: A mechanical emergency and parking brake system, for vehicles of the type having a power steering pump, includes a check valve having an input port coupled to the pump outlet and an output port coupled to hydraulically deactuated spring brakes through brake lines. A pilot check valve has its inlet port coupled to the input port of the check valve and an output or return port coupled to the power steering gear. The pilot port of the pilot check valve is coupled to the output port of the check valve so that the pilot check valve opens only when the pressure at the output port of the check valve is above a chosen pressure. This allows hydraulic fluid to flow from the pump, through the pilot check valve, through the power steering gear and to the reservoir. To reapply the brakes, the operator actuates a valve which disconnects the brake ports from the output port of the check valve and connects the brake lines to the reservoir.

Abstract: A spring-loaded parking-brake and service-brake system for trailers of motor-vehicle combinations is provided which increases safety. The system does this by allowing the service brake of the trailer to respond at the same time as the service brake of the towing motor vehicle, and the spring-loaded parking brake of the trailer to respond at the same time as the parking brake of the motor vehicle. To guarantee safe parking and maneuvering of the uncoupled trailer, the control system of the spring-loaded trailer parking brake is electrical, and furthermore the service brake is also controlled by an additional electrical signal. For this purpose two electrical coupling parts, a pneumatic control-line coupling and a pneumatic supply coupling are attached to the trailer.

Abstract: A fluid pressure braking system for a heavy vehicle is provided with a supply reservoir and a pair of service reservoirs which are charged from the supply reservoir through a corresponding pair of pressure protection valves. The emergency/parking braking system is charged directly from the supply reservoir through a pressure protection valve which is set to open at a pressure level greater than that at which the pressure protection valves protecting the service reservoirs open. Accordingly, it is not possible to release the emergency spring brakes until the service reservoirs are charged to a safe operating level, and it is not possible to bleed down both of the service reservoirs and to thereby effect an emergency brake application due to a single failure in the systems.

Abstract: A fluid pressure control system engages the power take-off of a tractor-trailer combination vehicle equipped with air brakes while simultaneously applying the parking brakes of both the tractor and the trailer. However, when the vehicle is to be moved and the power take-off disengaged, the vehicle operator must, in addition to moving the power take-off control to the position disengaging the power take-off, must also operate the parking control valves which release the parking brakes on both the tractor and the trailer. Accordingly, the parking brakes cannot be inadvertently released by merely disengaging the power take-off control, although engagement of the power take-off control automatically sets or applies the parking brakes on both the tractor and the trailer.

Abstract: An electropneumatic brake system for a railway vehicle having an electronic control unit that outputs a friction brake demand signal according to the difference between a brake command signal and a feedback signal representative of the effective dynamic brake, whereby the total dynamic and friction brake effort corresponds to the brake command signal. The brake system also includes a pneumatic operating unit having a pair of high-capacity, electropneumatic valves operated by the friction brake demand signal to regulate the pneumatic pressure at the brake unit directly, that is, without an intermediary relay valve. Such an arrangement provides better response and more accurate pressure feedback of the friction brake level to the electronic control unit. A service rate control choke is located ahead of the electropneumatic valves, which allows these valves to perform the emergency and wheel-slip control functions without requiring independent valves for this purpose, by virtue of their high-capacity capability.

Abstract: An air brake control system for use in truck trailers having at each axle compressed-air brakes including spring brakes and service brakes, and each trailer being coupled to receive compressed air through an emergency (supply) gladhand and to receive service brake signals through a service (control) gladhand, the invention comprising an integrated brake valve system for each axle of each trailer, including a common valve housing; a spring brake valve cluster having a non-return check valve connected to receive and pass air pressure from the emergency gladhand and to deliver it directly to the spring brakes and an air pressure responsive shuttle operative to open the check valve whenever the emergency line pressure falls below a predetermined spring brake isolation pressure above which the spring brake holding pressure is not affected by fluctuations of the emergency gladhand pressure; and including an air tank supply valve cluster connected between the emergency gladhand and the tank and operative to sense pr

Abstract: An air brake includes a service brake chamber which actuates a push rod. A collet brake chamber is partially defined by a collet brake diaphragm. A locking collet is mounted to the collet brake diaphragm and includes a bore through which the push rod passes. A collet brake spring biases the collet into a tapered collet hole to clamp the collet onto the push rod to prevent the movement of the push rod toward the brake off position. Application of pressure to the collet brake chamber overcomes the force of the collet brake spring and moves the collet away from the tapered collet hole to allow the push rod to move freely. An air supply system, including a quick release valve, a two way check valve, an emergency and parking air supply tank and a pilot check valve, in conjunction with a conventional quick release valve or another type of exhaust valve, automatically supplies air to the service brake chamber from the tank whenever the spring brake supply line is vented.

Abstract: Spring-applied, pressure-released brakes are useful, for example, in construction vehicles or other vehicles that require an automatic braking in the event of an engine failure. In order to tow the vehicle for service, the brakes must be released. Most brake release systems require an alternate pump and associated valves on each vehicle with the fluid from the alternate pump being controlled by the brake valve on the vehicle. The alternate pump on each vehicle add cost to the vehicle and the spool of the brake valve is a known path for fluid leakage thus requiring an alternate pump of a larger capacity than is actually needed. The present brake release mechanism provides an isolating mechanism that is effective to isolate a work port of a brake valve from a valving element in a housing. The isolating mechanism is adapted to connect with an alternate source of pressurized fluid and adapted to direct the pressurized fluid to a brake for release thereof.

Abstract: This invention relates to a rail vehicle brake system comprising an air brake cylinder (10, 11) with a piston (12) which is spring-biased for brake application on one side thereof, and a control system for selectively supplying pressurized air to said cylinder.On both sides of the piston (12) the air brake cylinder spaces (10, 11) are connected to a common control system (28, 31) for the supply of pressurized air thereto. The control system--by controlling the supply and discharge to and from the respective spaces--accomplishes a pressure differential between the spaces for service braking.

Abstract: Parking brake control apparatus on a vehicle equipped with electrofluidic responsive brakes is disclosed. The apparatus comprises a parking brake on the vehicle operable by a cylinder. A source of pressurized fluid provides fluid pressure to the cylinder. The cylinder responds to fluid pressure to release the parking brake and responds to apply the parking brake when fluid pressure is vented. A directional valve connected intermediate the source of fluid pressure and the cylinder controls fluid communication to the cylinder in one position and vents fluid pressure from the cylinder in a second position. Movement to the second position is controlled on one side of the valve by an electrovalve which responds to electrical signals and on the other side by a cylinder which responds to fluid pressure and can only occur when both an electrical signal is below a predetermined minimum and the fluid pressure is reduced.

Abstract: An electro-pneumatic control system (10) for a vehicle fluid pressure braking system controls communication to the trailer supply line (30) and to the vehicle spring applied, fluid pressure released parking brakes (78). Relays (66,92) are controlled by manually actuated switches (42,58) to actuate solenoid valves (74,84) which control communication to the supply line (30) and to the parking brakes (78). Actuation of the solenoid valves (74,84) is maintained by the relays (66,92) in response to pressure actuated switches (76,88) which are responsive to the pressure levels in the supply line (30) and in the parking brake (78).

Abstract: A hydraulic asymmetry detector for sensing differential movement of a pair of flight control surfaces, such as the wing flaps of an aircraft, which are actuable by actuating mechanisms. The detector has a pressure-regulator valve and a sensor valve, with the pressure-regulator valve operable in response to movement of one actuating mechanism to set a control pressure proportional thereto, and the sensor valve has a valve member which senses a force balance between a force created by the control pressure and a force which is proportional to the movement of the other actuating mechanism. The sensor valve member moves with a snap action when there is a force imbalance to result in setting one or more brakes for the actuating mechanisms to lock the actuating mechanisms and thereby limit the asymmetric condition within a manageable range.

Abstract: A towing circuit (20) for a hydrostatic travelling drive system with a prime mover, a variable displacement pump (3) and a travel motor (2) supplied thereby, a parking brake (6) arranged to be applied by a brake valve (9) and, optionally, a steering booster (30) and differential gear locking means (40) actuated by a change-over valve (34) has its inlets connected to the travel motor (2) through shut-off valve means (22). A filling pump (4) is connected to supply conduits (7,32) in which the brake valve (9) and the change-over valve (34), respectively, are arranged. Feeding conduits (26,45) provided with check valves open into these supply conduits (26,45). The feeding conduits (26,45) are connected with connecting conduits (21a,21b) governed by the shut-off valve means (22). During towing operation, the travel motor (2) driven by the wheels (1) generates the auxiliary pressures in the supply conduits (7,32) required for the operation of the steering booster (30) and the differential gear locking means (40).

Abstract: Fluid pressure braking system (10) for supplying fluid pressure to actuate the service brake actuators (26) and to supply hold-off pressure to release the spring brake actuators (22) of the trailer portion of a tractor-trailer combination vehicle includes a spring brake relay valve (32) having a delivery port (38) communicated with the spring brake actuators (26), a control port (34) communicated with the trailer supply line or conduit (12), and a supply port (36) communicated with the supply line (12) through a bypass passage (40). Accordingly, hold-off pressure can be supplied directly to the spring brake actuator (26) before the reservoir (44) is fully charged. The reservoir (44) is charged through the supply line (12) and a pressure protection valve (54) which opens to permit charging of the reservoir (44) only when the pressure in the system exceeds a predetermined level.

Abstract: An air brake includes a service brake chamber which actuates a push rod. A collet brake chamber is partially defined by a collet brake diaphragm. A locking collet is mounted to the collet brake diaphragm and includes a bore through which the push rod passes. A collet brake spring biases the collet into a tapered collet hole to clamp the collet onto the push rod to prevent the movement of the push rod toward the brake off position. Application of pressure to the collet brake chamber overcomes the force of the collet brake spring and moves the collet away from the tapered collet hole to allow the push rod to move freely. An air supply system, including a quick release valve, a two way check valve, an emergency and parking air supply tank and a pilot check valve, in conjunction with a conventional quick release valve or another type of exhaust valve, automatically supplies air to the service brake chamber from the tank whenever the spring brake supply line is vented.