Abstract: A combined load-sensing proportion and relay valve for an air brake system including a valve disk which has an exhaust passage in its axial center and is adapted to hold the valve in normally closed position, and a control piston unit which is actuated by an indicated pressure from a brake valve to move the valve disk and open the valve. The control piston unit includes a first pressure-sensing piston for controlling the valve-opening action of the valve disk and a second pressure-sensing piston coaxially connected to the first piston via a spring therebetween. A stroke adjusting device is provided to control the axial movement of the second piston correspondingly to the payload of the vehicle.

Abstract: A wheel lock-up prevention system for motor vehicles includes electromagnetic valves which decompress the main control chamber of the system when a wheel lock-up occurs and hence terminate the braking effort at the locked wheel. During re-compression, which takes place by cyclic actuation of one of the electromagnetic valves, excessively high pressure pulses are prevented by connecting the main control chamber with a surge chamber during part of the cycle so as to diminish the pressure in the main control chamber and to make the magnitude of the cyclic pressure increases inversely proportional to the total pressure in the control chamber.

Abstract: A dual brake valve for use in a twin-circuit fluid pressure-operated vehicle braking system comprises a housing, two sets of ports therein each including an inlet port and a delivery port, and two co-axial valve assemblies associated respectively with the two sets of ports, the valve assemblies each comprising a poppet-type valve element the head of which is subjected to delivery pressure, which pressure also acts on an oppositely-directed face of the valve element such that fluid pressure across the valve element is balanced. Preferably an axial exhaust passage is provided in part by a tubular member located co-axially between the valve assemblies by a diaphragm assembly which is also subjected to delivery pressure on both sides thereof.

Abstract: A brake pressure modulating control valve for a hydraulically operated brake system. The control valve includes a spool associated with an air spring chamber. The system includes equipment for modulating the air pressure in the air chamber for constantly and concurrently modulating the pressure of the hydraulic fluid in the brake system.

Abstract: A relay valve for transmitting an operational signal to a first brake applying servomotor in a trailer upon actuation of a second brake applying servomotor in a tow vehicle. The relay valve has a housing with a movable wall which sequentially interrupts the communication of vacuum to a power chamber in the first brake applying servomotor and thereafter allows air to be communicated to the power chamber. With air in the power chamber, an operational pressure differential will be developed which will operate the first brake applying servomotor.

Abstract: A valve unit for controlling air flow and braking pressure in the brake cylinder of a pneumatic braking system. The valve unit has an inlet and an outlet valve assembly each of which are controlled by a solenoid valve, which is in turn controlled by an electronic braking control system. In the inlet valve assembly there is a valve diaphragm which on one side is biased by one pressure to close the valve unit, and which on the opposite side is biased by two pressures to open the valve unit. The ratio between the areas affected by the respective pressures is selected in such a way that the brake cylinder pressure is raised in essentially constant steps.

Abstract: A shutoff and exhaust valve for tractor-trailer air brake systems operates to open or close communication between the tractor and trailer service lines in accordance with the pressure in the tractor emergency line and the trailer service line is exhausted to atmosphere through the same valve.

Abstract: A vehicle brake actuation system is disclosed containing fluid pressure to operate brake actuators for effectively combining an electro-pneumatic relay system to function with a skid control system. A first valve is connected in the system for releasing a first impulse of fluid pressure from a first container. A second valve is connected to receive the first impulse from the first container, a second pressure impulse from a second container and to release a thrid pressure impulse from the second container to the actuators. A first sensor senses fluid pressure between the first and second valves and produces a first signal in proportion thereto. A second sensor senses fluid pressure between the second valve and the actuators and produces a second signal in proportion thereto. A first logic circuit receives and compares the first and second signals for discriminately controlling communication of the first, second and third impulses with the second valve.

Abstract: A valve assembly in an air brake truck system which meets minimum response time specifications required by authorities and the maximum response rate required by the wheel lock control system for efficient operation. The valve assembly varies the effective orifice size between the air supply inlet and the outlet to the relay valve. The high minimum specified rate is provided for a short period of time for initial response and the lower maximum rate for efficient operation is provided for the remainder of the stop. The valve assembly has a timing section and a variable orifice section.

Abstract: The valve includes a main valve member having an axial exhaust passage and held in the normally closed state, and a control piston assembly for opening the valve member depending on the payload of the vehicle on which the air brake is installed. The control piston assembly comprises a control piston having a valve seat on its underside cooperable with the main valve member, a stepped piston composed of two portions with different diameters and located substantially coaxially with, and in spaced relation to, the control piston in a passage leading from an indicated-pressure inlet to the upper surface of the control piston, a valve assembly adapted to be opened and closed by the axial movement of the stepped piston to control the indicated pressure applicable to the upper surface of the control piston and to the stepped piston, and a loading spring engaging the upper end of the stepped piston, with its compressive load adjustable according to the payload of the vehicle.

Abstract: A fluid-pressure regulating valve for adjusting a supply pressure from either of two air reservoirs according to the payload of a vehicle and supplying the adjusted pressure to a control pressure chamber in a pressure-proportioning relay valve, the regulating valve comprising: a valve assembly for controlling the supply pressure, said assembly including a pressure piston reciprocably disposed in the valve body and formed with an air passage through the wall on one side, a supply valve accommodated in a supply pressure chamber inside the pressure piston and seated on a valve seat provided at the lower end of the supply pressure chamber, and an exhaust valve having an exhaust valve seat engageable with the supply valve and also having an upward protrusion extended through an exhaust bore formed in the axial center of the supply valve; an output pressure chamber defined between the underside of the pressure piston and the inner wall of the valve body; a balance spring disposed above the pressure piston in commun

Abstract: A combined load-sensing proportion and relay valve for an air brake system, comprising a valve disk having an exhaust hole in the axial center, and a control piston assembly for adjustably moving the valve disk to open the valve, characterized in that the control piston assembly consists of two pressure-sensitive pistons, the first of the pistons being formed with a downward projection having a valve seat at its lower end for face-to-face engagement with the valve seat, an indicated-pressure chamber communicated with an indicated-pressure inlet port is formed between the upper side of the first pressure-sensitive piston and the underside of the second piston, a control-pressure chamber communicated with a control-pressure inlet port is provided above the second pressure-sensitive piston, and engaging means is located between the first and second pistons.

Abstract: An improved wheel lock prevention device for use in the brake system of motor vehicles. The device has a relay valve included in assembly with a motor vehicle operator controlled brake velve, a wheel brake cylinder and a source of pressurized air. The relay valve has a primary and secondary pressure side. The primary pressure side is connected to the brake valve and the secondary side is connected to the wheel brake cylinder. A short circuit connection between the primary and secondary pressure sides is provided with a control for effecting a balancing of the pressures on both the primary and secondary pressure sides after the pressure on both sides has been reduced from a peak value by a desired extent during application of the brake system.

Abstract: Electro-pneumatic brake apparatus for railway vehicles including a dynamic brake portion and a fluid pressure operable brake portion both of which are actuated by a common variable signal which produces a corresponding control pressure for effecting operation of said fluid pressure operable portion, such control pressure also being simultaneously converted to an electrical control pulse for effecting operation of the dynamic brake portion at the same time as, or at least not ahead of, the fluid pressure operable portion. The apparatus is further provided with a combined electro-pneumatic monitoring device for determining the sufficiency of the combined brake application.

Abstract: An air brake system having a brake application valve controlling a relay valve by pilot pressure. A wheel lock control portion includes a valve for venting a relay valve pilot chamber upon actuation of a solenoid valve during antiskid operation of the system. A supply pressure restrictor mechanism, held inactive during normal conditions, operates upon closure of the solenoid valve to restrict the supply of pressure from the pressure source to the relay valve supply port in order to permit a slower brake re-application rate upon skid control termination. The pressure restrictor mechanism is returned to its normally inoperative state upon release of the brake application valve.

Abstract: A fluid pressure relay valve particularly for the electro-pneumatic control of vehicle brakes has a piston displaceable within a valve housing to define a control chamber on one side of the piston and on the other side of the piston there is a second chamber which is connected to the braking device. The pressure within the control chamber is controlled by inlet and outlet solenoid valves. The piston actuates valve means for controlling the pressure in the second chamber by venting the chamber or by connecting the chamber to a source of fluid pressure. An additional volume of pressure medium is connected to the control chamber for the purpose of increasing the pressure in the control chamber subsequently to the release of the signal "hold the pressure." The increase in pressure is to a predetermined level which is a function of a controlled lowering of pressure in the additional volume.

Abstract: The valve comprises a relay valve unit constituted by a main valve disc having an axial exhaust bore therethrough, and normally biased to a closed position, and a control piston assembly for adjustably moving the main valve disc to the open position, and a modulated-pressure control valve unit operable to supply a pressure, modulated in accordance with the loading of the vehicle, to the control piston assembly. The control piston assembly includes first, second and third pressure-responsive pistons with the first piston being cooperable with the main valve disc and the third piston being interengageable with the first and second pistons. A loading spring is engaged with the second piston, an indicated pressure chamber is formed between the first and second pistons, and a modulated-pressure chamber is formed beneath the third piston and is in communication with the control valve unit.

Abstract: In an anti-skid pneumatic braking system for vehicles a brake is applied by air from a first reservoir and the braking effort modulated by air from a second reservoir. The brake is connected to the second reservoir through two normally closed diaphragm valves in series, the first valve opened by air supplied to the brake from the first reservoir when the brake is applied and the second valve opened by air supplied from the second reservoir in skid conditions. Additionally a third normally closed diaphragm valve can be connected across the diaphragm of the brake actuator and is opened in skid conditions.

Abstract: A combined load-sensing proportion and relay valve for an air brake system including a valve disk which has an exhaust passage in its axial center and is adapted to hold the valve in normally closed position, and a control piston unit which is actuated by an indicated pressure from a brake valve to move the valve disk and open the valve. The control piston unit includes a first pressure-sensing piston for controlling the valve-opening action of the valve disk and a second pressure-sensing piston coaxially connected to the first piston via a spring therebetween. A stroke adjusting device is provided to control the axial movement of the second piston correspondingly to the payload of the vehicle.

Abstract: A brake application valve is used to connect supply tanks to the front and rear brakes of a vehicle. The valve has a pair of shuttle members which normally close communication between the inlets and the outlets and open communication between the outlets and exhaust. There are two pistons, movement of which is effective to cause the shuttle members to open communication between the inlets and outlets and close communication to exhaust. One of the pistons (second piston) has inner and outer portions, with the inner portion being provided with a mechanical connection to the first piston such that movement of the first piston can cause movement of the second piston inner portion. The outer portion of the second piston is exposed to pressure at one outlet to cause movement of the second piston in response to air pressure at the first outlet.