Patent GB-911340-A (GB)
Title: Remote control hydraulic system
Inventor: BANKER OSCAR H
IPC: B62D5/093
Filed: 1961-04-20
Abstract: 911,340. Power steering. FAWICK CORPORATION. April 20, 1961, No. 14274/61. Class 79(5). A hydraulic steering apparatus comprises a piston mounted for reciprocation within a cylinder, a shaft extending axially through the piston arid journalled at one end in a housing for relative axial movement therewith, a threaded connection between the. shaft and piston, means limiting axial movement of the shaft relative to the housing, valve means axially fixed to the shaft, the housing having ports, the opening and closing of which is controlled by axial movement of the valve on the shaft, means for preventing rotation of the piston in the cylinder and external means for rotating the shaft in the cylinder, the housing having passages therein connecting the ports to opposite sides respectively of the piston. A housing 35 is sealed at one end by a cover plate 36 having an inwardly extending cylindrical flange 37 which extends within the bell-mouthed end of a double-ended piston 46, 42 having sealing rings co-operating with cylindrical portions 38 and 43 of the housing 35. When the piston is in the middle of its movement, the chambers 39 and 51 each side of piston ring 47 are of equal volume The chambers 39 and 51 are connected by lines 17 and 16 to chambers 30 and 31, respectively, formed between the ends 28, 29 of a double-ended piston and slave cylinder 15, the piston being connected through rack 32. pinion 33 and a link mechanism 14, 13, 12 to the steering arms of the vehicle wheels 10 and 11. A valve housing 19 is connected to the cover 36 and is supplied with pressure fluid. from a reservoir 22 by a pump 21 through line .24 and inlet 60 leading to passage 61 from which the liquid may pass through passages 66 and 67 to chamber 65 formed between the flange 37 and the interior of piston 46 or through passages 70, 71 and 72 to the chamber 68 formed between the piston end 42 and the housing 35. The passage 72 is formed in a pin 74 extending through the piston member 42, 46 and preventing it from rotation. A shaft 77 is attached to a; hand wheel 20 and is connected by a recirculating ball type thread with the piston member 42 and has an extension 85 connected to an open centre valve spool member 75 normally held centred by a spring 76, radial and end thrust bearings being provided for the shaft 85, 77 to allow slight axial movement when the wheel 20 is rotated, produced by reaction from the steering wheels 10 which are tended to be turned by movement of the piston 46, 42 in the telemotor system comprising piston 46, 42 and slave cylinder 15. The slight axial movement of the shaft 77 displaces the valve spool 75 in a direction according to the direction in which the hand wheel 20 is turned and power assistance is then provided by pump 21 supplying either chamber 65 or 68 from the passage 61. Return fluid passages 64 are provided. In the event of pump failure, manual steering is obtained by movement of the piston 46, 42 by the screw thread 79 and fluid may be circulated. between the chambers 65 and 68 through a non-return valve 107. The operation of filling the system with fluid and "bleeding" are described, bleed valves 95 and 96 and spring- loaded non-return valves 93 and 100 being provided for this purpose. Specification 859,813 is referred to