Patent GB-690447-A (GB)
Title: New of improved apparatus for automatically maintaining uniform floor height in vehicies
IPC: B60G11/32
Filed: 1950-12-08
Abstract: 690,447. Adjusting body height. DAIMLERBENZ AKT.-GES. Dec. 8, 1950 [Dec. 8, 1949], No. 30145/50. Class 108 (ii). In apparatus for automatically maintaining a uniform floor height in vehicles with varying axle load, the variation of the distance between the superstructure of the vehicle and the road surface is counteracted by automatic adjustment means which is rendered operative or inoperative depending upon whether the vehicle is at rest or travelling. In the arrangement shown, in which a rigid axle 1 is pivotally connected to a chassis 4 through a link 2, and in which a suspension spring 5 bears at its upper end against a spring-loaded piston 8 slidable within a cylinder 9, the latter communicates with a casing 12 in which a piston valve 13 controls the admission and discharge of pressure liquid to and from the cylinder. The movement of the valve 13 is controlled by movement of the link 2 through a rod 14. The casing 12 communicates with a second casing 19 in which a piston valve 20 controls the admission of pressure liquid to the casing 12 from a pressure pump 26 which may be driven from the engine of the vehicle. Movement of the valve 20, which takes place only when the vehicle is stationary, is controlled by a spring- loaded piston 30 through a linkage 29, and movable in a cylinder 32 by liquid pressure from a pump 33 driven, for example from the propeller shaft. In operation, relative movement of the axle 1 and chassis 4 from the position shown, while the vehicle is stationary, causes pressure liquid to flow into or out of the cylinder 9 through a pipe 11 and ports 15 and 21 or ports 16 and 22 in the valves 13 and 20 respectively, until the valve 13 regains the position shown in which it closes the pipe 11. Upon movement of the vehicle, piston 30 is moved by liquid pressure from the pump 33 to prevent admission of liquid to the casing 12 and pressure liquid from pump 26 is returned to a reservoir 27 through a spring-loaded valve 28. Liquid is returned from the cylinder 32 to a reservoir 34 through a restriction 36. The piston 30 may additionally control an overflow aperature in the cylinder 32. The reservoirs 27 and 34 may be combined. In another arrangement, Fig. 2 (not shown), the axle is sprung by means of a leaf-spring which is supported at each end by a piston movable in a cylinder against liquid pressure. Both cylinders communicate with a valve casing in which a piston valve mechanically coupled to the axle, controls the admission and discharge of pressure liquid to and from the cylinders. Admission of liquid to the casing while the vehicle is moving is prevented by a piston valve which is actuated through spring-loaded linkage by a ring which is in light frictional contact with a shaft in driving connection with the axles. An equalizing rod is connected between the pistons supporting the suspension spring. In another embodiment, Fig. 3 (not shown), comprising a leaf-spring suspension, the leaf-spring is connected to the chassis through angle levers which are connected to either side of a piston movable against springs towards either end of a pressure cylinder. The cylinder communicates at each end with a valve casing in which a slide valve is movably connected with the vehicle axle. Liquid flow to the casing is controlled by a valve which is movable in a second casing under the action of a speed governor of known type disposed on the propeller shaft. In this arrangement, no adjustment of the body height is permitted in either direction of travel of the vehicle. In a further arrangement, Fig. 4 (not shown), in which each road wheel is mounted on a longitudinal link, with a coil spring between the link and the chassis, the link is pivotally connected to the chassis through an angle lever which is connected to a piston movable towards either end of a pressure cylinder. The latter communicates at each end with a slide valve casing similar to that of the Fig. 3, embodiment and liquid flow to this casing is controlled similarly to that of the Fig. 2 arrangement. In another arrangement, Fig. 5 (not shown), a link is connected to the chassis through one end of a torsion spring, the other end of which is mounted in a toothed wheel segment which is rotatable through a worm and gearing by an electric motor. A change over switch is actuated through a link by relative movement of the link and chassis to actuate the motor to maintain the chassis at the required normal height. A spring-loaded switch in the motor circuit is actuated to open the latter by means of a friction ring on a shaft in driving connection with the axle, when the vehicle moves forward. A further friction ring may be provided to close a switch when the vehicle is at rest or moving forwards, but opens when the vehicle moves backwards.