GB870907A - Improvements in or relating to automatic steering for motor vehicles - Google Patents

Abstract

870,907. Tractors; automatic steering. FORD MOTOR CO. Ltd. (Ford Motor Co.). March 1,1960. No. 7246/60. Class 79(5). The closely spaced front wheels 10 of a tractor are mounted on a spindle assembly 11 rotatable about a vertical axis by a steering arm 12 acted upon by a hydraulic ram 14. The steering wheel 21 of the tractor acts through a mechanism 20 and pitman arm 19 upon a drag link 17 which acts upon a valve 16 to provide power assisted steering. A feeling device is mounted at the front of the tractor and comprises converging arms 65, 66 attached to a rotatable shaft 50 carrying levers 51 which co-operate with normally open microswitches 45 connected in a circuit (Fig. 8) including relays 48 and an electric motor 40. The drag link 17 includes mutually engaging threaded portions 34 and 35 (Fig. 6), the former being rotatably connected through gears 42, 44 to the motor 40 which is carried by the drag link. Any tendency for the tractor to deviate from its course causes, through the feelers 65, 66, rotation of the shaft 50 which closes one or other of the switches 45 and rotates the motor 40 in a direction according to the direction of deviation and so lengthens or shortens the drag link 17 to produce a steering correction. To prevent hunting, the switches 45 are contained in a box 46 mounted upon the shaft 50 and prevented from rotating relative to the shaft by a lever 80 attached to a flexible cable 75, the other end of which is attached to the member 37 at one end of the drag link 17. The sheath 76 of the cable is attached at one end to an arm 82 connected to a sleeve 60 through which passes the shaft 50 and at the other end to a clamp 77 to a part of the drag link 17 movable relative to the member 37, so that lengthening or shortening of the drag link causes rotation of the box 46 to provide a follow up motion opening the circuit of the electric motor 40 to prevent additional corrective steering of the tractor wheels. A link work comprising members 31, 64, 62, 61 is connected to the bracket 54 upon which the feeler member is mounted and to the mechanism for raising and lowering the implements so that when the implement is raised the feeler is also raised to an inoperative position. The members 65 and 66 are mounted for adjustment towards or away from one another. Specification 779,121 is referred to.