GB560148A - Improvements in or relating to power assisted steering gear for vehicles - Google Patents

Abstract

560,148. Valves. CLAYTON DEWANDRE CO., Ltd., and RODWAY, J. July 9, 1942, No. 9554. [Class 135] [Also in Group XXXI] In a vehicle having two steering hand-wheels 1, 2 the movements of either of which control one of a pair of valves 9, 10, 9a, 10a to set in operation a vacuum or pressure cylinder 24 connected to the steering road wheels, automatic means such as valves 20, 21 are provided between the control valves to ensure that only one control valve is operable at any one time. In the construction shown, the hand-wheels 1, 2 are connected by steering-gears 37, 37a and arms 6, 6a to the steerable road wheels (not shown) and rotation of either hand-wheel applies a torque through differential or epicyclic gearing to a radial stud 8 or 8a so that this stud opens one of the control valves to admit compressed air from a reservoir 11 to the steering cylinder 24 the piston of which is connected to an arm 26 operating the road wheels. In the normal positions of the hand wheels all four control valves are shut. If the valve 10 (say) is opened by rotation of the hand wheel 1 in one direction air is admitted from the reservoir 11 through pipes 12, 14, valve 10 and pipe 19 to valve 21. This valve comprises a loose valve member 30 having surfaces 31 of resilient or yieldable material' adapted to make fluid-tight contact with either of two seats 27, 28. The valve chamber has two inlet ports 32, 33 connected to the pipe 19 and an outlet port 34 connected by a pipe 22 to one end of the steering cylinder 24. A similar valve 20 is provided in the pipe 18 connecting the valves. 9, 9a and is connected by a pipe 23 to the other end of the cylinder 24. Thus, when the valve 10 is opened and admits pressure air to the valve 21, the valve member 30 is forced against the seat 27 sealing the right-hand part of pipe 19, and air flows freely past the valve 30 to the cylinder to operate the steering gear in the desired direction. If the other hand-wheel 2 is operated to open the valve 10a the valve 30 is forced off the seat 27 and against the seat 28 thus shutting off the left-hand end of the pipe 19. For steering in the opposite direction one of the valves 9, 9a is opened. The steering shafts 3, 4 drive differential gears the output members of which are fixed to the driving members of worm steering gears 37, 37a, the studs 8, 8a, being fixed to the planet carriers of the differential gears.