Patent GB-566575-A (GB)
Title: Improvements relating to hydraulic vibration dampers for use on road vehicles and other purposes
IPC: F16F9/512
Filed: 1943-03-26
Abstract: 566,575. Hydraulic vibrationdampers. LUCAS, Ltd., J., and PITT, H. W. March 26, 1943, No. 4947. [Class 108 (iii)]. Relates to a hydraulic vibration-damper for damping the movements of a resiliently mounted wheel of a road vehicle, aircraft undercarriage, &c., of the kind in which little or no resistance is offered to initial movements of the wheel spring, the damping action being effective wholly or mainly on the return movements. According to the invention, the damper comprises a pair of pistons h housed in a cylinder or cylinders b, a valve o for controlling flow of liquid on movement of the pistons, and means responsive to the load on the wheel spring for adjusting automatically the position of the valve. As shown, the cylinders b form the ends of a casing a having a liquid reservoir c surrounding a spindle e to which are secured a lever d and a second lever (not shown) connected to the spring f, Fig. 2, or wheel axle g. The lever d engages a stem i uniting the pistons h, each of which contains a non-return valve j and a restricted orifice k, and an axial bore m extending through the pistons and stem i communicates at its enlarged centre portion q with the reservoir c through a lateral port or ports n in the stem. The control valve o arranged in the bore m is in the form of a rod having a central part p adjacent the ports n adapted to fit closely in the bore, the other parts of the rod being of smaller diameter to allow free flow of liquid between the cylinders and reservoir. One end of the rod is supported in an extension of one cylinder b and the other end is integral with or secured to a piston in an extension t of the other cylinder which is connected by a pipe u to an air cylinder v secured to the vehicle chassis adjacent the spring f, a piston x in the cylinder being connected to the spring f or axle g. In operation, assuming the valve o is stationary, movement of the pistons h causes flow of liquid from one cylinder b to the reservoir c through the bore m and ports n, while liquid flows freely from the reservoir to the second cylinder b past the non-return valve of the associated piston. During the return movement, however, when the volume of the second cylinder is being reduced, the valve rod o prevents free flow of liquid from this cylinder until the central part p of the valve rod again comes opposite the enlarged portion q of the bore m, liquid from the cylinder meanwhile passing to the reservoir through the associated restricted orifice k. Variation of the load on the spring f causes variation of the position of the pistons h relatively to the valve rod, but this is compensated for by corresponding adjustment of the valve rod by variation of the air pressure in the cylinder v. In a modification, the lever d is dispensed with, and one of the pistons is formed with a hollow extension passing through the end of the corresponding cylinder and attached to operating means. The non-return valve j and/or orifices k may be provided in the body of the damper instead of the pistons.