Patent GB-840649-A (GB)
Title: Load control valve for vehicle air springs
IPC: B60G17/052
Filed: 1958-08-11
Abstract: 840,649. Adjusting body height. BENDIXWESTINGHOUSE AUTOMOTIVE AIR BRAKE CO. Aug. 11, 1958 [Sept. 13, 1957], No. 25763/58. Class 108(2). A levelling valve 10 for a road vehicle air suspension system is only operative when air from a reservoir is supplied to the levelling valve, this supply being controlled by a subsidiary three - way valve (not shown). The subsidiary valve normally only connects the air supply to the levelling valve when the vehicle is at rest, thus, movements of the levelling valve due to road irregularities do not affect the levelling of the vehicle. Ports 27, 32, are connected via the three-way valve to a reservoir of compressed air. A port 12 is connected to an air spring. In operation, opening a door of the vehicle operates the' subsidiary valve to connect the air reservoir with the valve 10. Thus air under pressure is admitted to the ports 27 and 32 of the valve 10. When this occurs, a piston 38 is forced down against a spring 40 so that a plunger 44 can frictionally engage a cam 58. The cam 58 is turned by an arm 18 which is connected to an unsprung portion of the vehicle. Simultaneously, a piston 68 is forced down against a stop 70, and an O-ring valve 90 is opened to connect an exhaust cavity 54 to exhaust ports 89. Since the vehicle is assumed to be initially levelled with the lever 18 in its neutral position, a valve 51 will be in lapped condition; that is, just seated on an abutment 53 to close the exhaust, and with a portion 50 of the plunger 44 just bearing against the valve member 51 to close an inlet aperture 56. If the load on the vehicle now decreases, the arm 18 will rotate and cause the cam 58 to lift the plunger 44 and also the valve member 51 until it is above the abutment 53. With the valve 51 in its upper position air is exhausted from the spring through port 12 a cavity 48, an opening 52 and the exhaust cavity 54, which is connected to exhaust ports 89. As the pressure in the spring is reduced the plunger 44 allows valve 51 to close the opening 52 and shut off the connection between the spring and the exhaust. If the load on the vehicle is increased, lever 18 turns the cam 58 to allow the plunger 50 to move away from the inlet aperture 56, so that air under pressure is admitted to the springs from a cavity 66 via a port 86, a valve 84, a port 88, the opening 52, the cavity 48 and the port 12. Air is admitted until the plunger 50 closes the aperture 56. If the vehicle door is now closed the subsidiary valve cuts off the connection between the air reservoir and the valve 10 and connects the latter to exhaust. Thus, air is exhausted from above the piston 38 causing its spring to move the portion 42 into engagement with the plunger 44 to move the latter out of engagement with the cam 58. Simultaneously, air is exhausted from the cavity 66 thus permitting the piston 68 to move to the position shown in Fig. 2. Also a spring 74 closes the valve 84 thus preventing any back-flow of air from the spring to the inlet conduit. Since piston 68 is now in its upper position,. O-ring valve 90 is engaged with the casing 34 thus closing the connection between the exhaust cavity 54 and the exhaust ports 89. If -required piston 38 may be eliminated so that the valve 51 is continuously reciprocated by the cam 58. The subsidiary valve may be operated by means other than the vehicle doors.