GB817830A - Improvements in steering mechanism - Google Patents

Abstract

817,830. Vehicle power steering. KENT Ltd., G. Feb. 21, 1956 [Feb. 21, 1955], No. 5185/55. Class 79(5) A power assisted steering mechanism comprises a piston and cylinder unit C, Figs. 4 to 6, a control valve, a tube 5 connected to the valve spool 16 and to the manually operable part of the steering mechanism, and another tube 9 connected to the other part of the valve, to the piston 17 and to the transmission of the steering mechanism, the tubes 5, 9 being movable relative to the cylinder 18, connected together by a lost-motion device, and constituting supply and exhaust conduits to and from the unit. As further shown in Figs. 4 to 6 the invention is applied to a rack and pinion steering gear, the steering shaft 47 being connected by gearing 45, 46 to a pinion 25 engaging a rack 24. The rack 24 is connected by the tube 5 to the valve spool 16 and the tube 9 surrounding the tube 5 is connected to a block 26 connected by track rods 27 to the steerable wheels (not shown). The cylinder 18 is secured to a tube 29 in which the block 26 is slidable. The block 26 is provided with supply and exhaust connections 20, 22 leading to a hydraulic pump (not shown), the connection 20 leading to the bore 21 in the tube 5 and the connection 22 to the annular space 23 between the tubes 5, 9. The spool 16 has lands 31, 32, 33, 34, the bore 21 leading to a duct 30 between the lands 32, 33. The piston 17 has lands 35, 36, 37, 38, 39, the space 23 being connected by a bore 41 to ducts between the lands 35, 38 and 37, 39. The piston 17 also has bores 40 each leading to opposite faces of the piston, the bores 40 being connected to ducts between the lands 35, 36 and 36, 37, whereby manual rotation of the shaft 47 causes movement between the spool 16 and piston 17 to cause one end of the cylinder to be connected to exhaust and the other end to exhaust to cause power assisted movement of the block 26. Relative movement between the spool 16 and piston 17 is resisted by a ball 43 in a bore 42 engaging a groove 44 in the bobbin 16, the ball being urged into engagement with the groove by a spring and by hydraulic pressure, the bore 42 being connected by a passage 45 to the duct 30. In a modification Fig. 1, the cylinder 18 is secured at 19 to a fixed part of the vehicle, the tube 9 is connected by a block 8 to a drag link (not shown), and the tube 5 is connected by a block 4 to the drop arm of a cam and follower steering gear (not shown), the tube 5 carrying within the block 8 a flange abutted by two springs in turn abutting the block 8 whereby relative movement in the valve on manual actuation of the gear is resisted.