GB857554A - Improvements in or relating to tandem axle suspension units - Google Patents

Abstract

857,554. Mounting bodies on, and springs for, road and rail vehicle axles. EATON AXLES Ltd. Oct. 31, 1958 [Oct. 29, 1957; Feb. 4, 1958], Nos. 33697/57 and 3590/58. Classes 103(6), 108(2) and 108(3). At least two axles 3, 4 of a vehicle have associated ram and cylinder units 12, 11 connected in a common hydraulic system in which a body of gas 24 is enclosed. As shown in Figs. 1 and 4, the axles 3, 4, are connected respectively by leading and trailing sets of links 7, 9, and 8, 10. Each lower link 7, 8, is connected to a respective ram member 12 which has a rubber-bush resilient connection with a piston 31 slidable in one end-portion of the cylinder unit 11. Liquid is contained in spaces 25, 32, on either side of each piston, and is retained by a rolling type seal 29. A partition 26 separates the liquid spaces 25 from the air space 24. The pistons 31 are each rigid with a respective plunger 28 both of which operate in a common oil-filled cylinder 39. Vehicle height is controlled by a valve assembly 53 (Fig. 5) which governs the admission of liquid to the spaces 25 from a pump 50. When the vehicle is at rest, liquid remains under pressure between the plungers 28 and is connected by a passage 22 and conduit a with the space above a floating piston 62 in the valve assembly 53. This causes a piston valve 57 to be depressed into a position which permits flow from the pump 50 via a conduit b to pass via a conduit c to one of the spaces 25 (there is a connection-not shown-between the two spaces 25 internally of the cylinder unit 11). When the vehicle commences to run, the pump 50 commences and liquid thereby forced into the spaces 25 acts on partitions 26 to pressurize the pneumatic space 24. The plungers 28, with pistons 31, then move apart, and pressure acting on the piston 62 (of valve assembly 53) is relieved. Compression damping is afforded by a valve assembly 68 and rebound damping by a valve assembly 70. A solenoid 69 may be operated to increase the damping of the assembly 68. A supplementary hydraulic accumulator 72, embodying an air spring, may be normally isolated from the system, but may be cut in when the volume in the space 24 is reduced below a predetermined minimum. In a modification, (Figs. 6 and 7, not shown), the partitions 26 are replaced by a flexible bag form of air spting.