Patent GB-1202490-A (GB)
Title: Control devices for the automatic guiding of mobile agricultural machines
IPC: B62D1/26
Filed: 1968-12-20
Abstract: 1,202,490. Automatic steering mechanism. MASCHINENFABRIK FAHR A.G. 20 Dec.; 1968 [21 Dec., 1967; 2 Oct., 1968], No. 60679/68. Heading B7H. In control means for automatically guiding a mobile agricultural machine carrying a mower unit along the boundary between mown and unmown parts of a crop, a sensing device 1 disposed ahead of the mowing unit comprises two discs 11, 12 which are toothed for engagement with the unmown crop and are rotatable about substantially vertical axes spaced transversely of the direction of travel so that the rotational or non-rotational state of the discs 11, 12 is dependent on the distance between the sensing device 1 and the crop boundary. Connected to each disc 11, 12 by a friction or magnetic slip clutch is an actuating member for electric, hydraulic or pneumatic switch means for producing signals which control the steering mechanism of the machine in such a way that if both discs 11, 12 rotate the steering mechanism operates to increase the distance of the sensing device 1 from the crop boundary, and if both discs are stationary the steering mechanism operates to reduce the distance. As shown, a combine harvester has a mowing unit 8 and rear wheels steered by an hydraulic cylinder 7. The sensing device 1 is carried by an arm 2, a linkage 3 which supports the sensing device so that the discs 11, 12 are substantially horizontal and includes an hydraulic cylinder 41 for adjusting the distance of the sensing device from the ground and pivoting the sensing into a raised inoperative position. A plate 35 carrying the linkage 3 pivots about a vertical axis 42 under the control of an hydraulic cylinder 45 which is connected to a feedback cylinder 46 associated with the steering cylinder 7 so that turning of the steered wheels causes corresponding lateral displacement of the sensing device 1 to avoid oversteering. The cylinders 45, 46 are connected by an hydraulic circuit, Figs. 8, 9 (not shown), including adjusting means which automatically modify the feedback action to accommodate oblique running of the machine when working on a slope. The discs 11, 12 are mounted beneath a wedge-shaped shield 13, the disc 12 by means permitting variation of the lateral spacing of the discs. A stalk deflector bow 18 is provided on the shield 13, and a protective skid may be provided below the discs 11, 12. The teeth on the discs 11, 12 may have downwardly directed projections at their extremities. In another embodiment, Fig. 3 (not shown), the discs 11, 12 project one on each side of the shield 13 which has an adjustable stalk-dividing tip. In Figs. 10, 11 (not shown), the sensing device is mounted on and is retractible into one stalk divider (102) of a mowing unit (103). In Figs. 13, 14 (not shown), the sensing device is mounted on the front axle of a tractor carrying a mowing unit (156). In Fig. 16 (not shown), two sensing devices are mounted, one on each stalk divider (102, 102<SP>1</SP>) of a mower unit (103) mounted on a combine harvester by means of a linkage which provides for lateral displacement of the unit by a feedback link (200) and vertical displacement of the unit by an adjusting device (202).