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 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: 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 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: 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: 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.