GB1291152A - Multi-axle power-assisted steering - Google Patents

Abstract

1291152 Hydrostatic steering systems CAM GEARS Ltd 2 June 1971 [9 June 1970] 27865/70 Heading B7H In a vehicle servo steering system a plurality of steering axles have individual sensing means for gauging the magnitude and sense of direction of the steering forces and individual motor means apply a proportional counterforce to each respective axle. In a preferred embodiment, Fig. 1, actuator rods 1, 2, acting upon pivotal stub-axles of a pair of steerable wheels (not shown), slidably extend through respective actuator assemblies AA1, AA2, each comprising a double-acting hydraulic ram HM1, HM2. Transverse motion of actuator rods 1, 2 is initiated from the steering wheel through rack- and-pinion gear-boxes RP1. RP2. Torque sensing elements TE1, TE2 operate respective spools. 18, 19 of valves V1, V2 in relation to magnitude and sense of direction to the torsional forces and each of the spools 18, 19 have three positions such that upon rotation in either direction of the steering wheel fluid pressure from motor P is directed accordingly to hydraulic motors HM1, HM2 to exert forces on actuating rods 1, 2 respectively in direct opposition to the steering forces in the rods. Other arrangements show alternative locations of the torque sensing elements TE1, TE2 in which TE1 is connected between gear-box RP1 and input shaft S1, Figs. 2, 3 (not shown), or torque sensing elements TE1, TE2 being connected to two input shafts S1, S2 in parallel arrangement, Fig. 4 (not shown). Also the valves may be connected in parallel as in Figs. 3, 4, and the valves and related torque sensing elements may be combined in a single valve block rigidly attached to a steering box in the interest of economy. Electrical or pneumatic power may alternatively be employed to hydraulic power and the valves V1, V2 may be of rotary rather than shuttle type.