Patent GB-1150806-A (GB)
Title: Improved vehicle leveling system
Inventor: HIGGINBOTHAM W W
IPC: B60G17/015
Filed: 1967-03-23
Abstract: 1,150,806. Vehicle levelling systems; power steering. MONROE AUTO EQUIPMENT CO. 23 March, 1967 [24 March, 1966], No. 13685/67. Headings B7D and B7H. A vehicle levelling system comprises a source of pressure fluid, e.g. from a power steering unit 12, supplied to a double solenoid valve 34 connected with a battery 20, a line 170 connecting the valve 34 with a fluid accumulator 32 which supplies or receives fluid to or from, respectively, a pair of adjustable shock-absorbers 26, 28, and a switch assembly 30 which is mounted on the sprung portion of the vehicle to detect the height thereof relative to an axle 24. Assuming the vehicle to be initially in an unloaded equilibrium condition and then suddenly loaded. The link members 122, 124, 126 (Fig. 1), will occupy the position A shown in dotted lines causing a casing portion of switch housing 38 to rotate and after a predetermined amount of rotation allowing shaft 114 to rotate in an anti-clockwise direction. Shaft 52 will then move to the left, closing contacts 76, 80 and completing a circuit comprising conductors 550, 548, 554, 556, and earth, whereby solenoid 184 of valve 34 is energized. A bore 232 of valve 34 is connected by conduit 166 with the power steering pump 168, a bore 234 is connected by conduit 164 with the power steering valve 14, a bore 236 is connected by conduit 172 with the reservoir 174 of the power steering, and a bore 238 is connected by conduit 170 to accumulator 32. Energization of solenoid 184 will cause armature 200 to move to the right thereby biasing valve member 324 away from the righthand end of bore 278 to communicate bore 288 with the interior of check valve housing 268, whereby a check valve member 282 will be disengaged from valve seat 276 due to fluid pressure in bore 288. As armature 200 moves to the right, sleeve member 308 will move into registry with ports 300 to limit the flow of pressure fluid from bore 288 to bore 234, and hence to valve 14. The remaining fluid flows through bore 274 in the check valve housing to conduit 170 and via the bore 460 of accumulator 32, into the interior of the housing 328 thereof. The pressure fluid at a pressure greater than 140 p.s.i. causing piston 532 to move to the right compressing nitrogen gas between the piston and header 332. When the nitrogen gas is compressed to 140 p.s.i. fluid then passes from bore 460 via conduits 456, 458 to expand the shock-absorbers 26, 28 and raise the rear end of the vehicle. If the vehicle is overloaded fluid pressure in housing 328 will cause piston 408 to move to the left so that an extension 442 will break the circuit to the solenoid by parting clips 384, 386. The flow of pressure fluid to the accumulator will then cease. The space within housing 328 between piston 408 and header 334 is also filled with nitrogen gas at a pressure greater than that at the opposite end of the housing. If the vehicle is unloaded and the linkage takes up position B indicated in Fig. 1, shaft 52 (Fig. 2) will rotate to the right, closing contacts 82 and 78. Solenoid 184 is thus deenergized, cutting off the flow of pressure fluid from the pump 168 to the accumulator 32 and solenoid 186 will be energized. Armature 202 will be caused to move to the left bearing valve member 250 out of valve seat 244 to permit the flow of pressure fluid from bore 238 to bore 236. Accordingly fluid will flow from the shockabsorbers 26, 28 via the accumulator 32 to the reservoir 174 causing the rear end of the vehicle to be lowered. If the rear end of the vehicle is jacked up and the pressure in the shockabsorbers is reduced while solenoid 186 is energized, piston 528 will move to the left and break members 490, 492 which form part of the solenoid circuit thereby de-energizing the solenoid and avoiding loss of all the pressure fluid in the shock-absorbers to the reservoir. Road shocks are damped out in valve assembly 30 by filling it with a viscous fluid, providing a detent 106 at the upper end of shaft 52 and a variable aperture between a lower extension 62 of the shaft and a boss 108. A lost-motion device is also provided with valve assembly 30 so that shaft 52 is not rotated until after a predetermined movement of linkage 122, 124, 126.