Patent GB-1397187-A (GB)
Title: Hydrostatic drive system
IPC: A01D41/12
Filed: 1973-04-30
Abstract: 1397187 Hydrostatic transmission control; linkwork; Bowden cables DEERE & CO 30 April 1973 [28 April 1972] 20445/73 Headings F2D and F2K In a hydrostatic transmission control system for a combine harvester wherein a pump displacement control lever 17 is normally controlled by a lever 1 and a pedal 7 overrides the lever 1 to temporarily reduce pump displacement, the pedal 7 is connected by a cable 8 to a block 28 carrying a horizontal slide 32 having pins 34, 35 respectively engaging slots 70, 38 in an adjusting member 36 connected to the lever 17 and a lever 39 which is tilted about a fixed pivot 42 by movement of the lever 1. On depression of the pedal 7 the slide 32 is moved transversely to its length and the pin 35 moves along the inclined slot 38 whilst the pin 34 effects an overriding axial movement of the adjusting member 36. As shown, the lever 1 is connected directly to the lever 17 by the inner core of a Bowden cable having a two-part outer sheath 44, 44a, the first part 44 of which is connected between the lever 1 and a fixed housing 20 in which the adjusting member 36 is axially slidable. The second part 44a of the outer sheath is connected between the adjusting member 36 and the lever 17. When the pedal 7 is released the pin 35 of the slide 32 is coaxial with the fixed pivot 42 which permits movement of the lever 1 to be transmitted through the inner core of the Bowden cable to the lever 17 and pivoting of the lever 39 by a block 43 fast with the inner core without effecting axial movement of the adjusting member 36. Subsequent depression of the pedal 7 acts through the block 28 to move the slide 32 down and thus effect axial movement of the adjusting member 36 and outer sheath 44a in the same direction as the original movement of the inner core to reduce pump displacement. The overriding movement may reduce pump displacement to zero and, in the forward direction of vehicle travel, may reverse pump displacement. During reverse travel of the vehicle a stop 46 prevents the override from reversing pump displacement. In an alternative embodiment the lever 1 is connected by a link to the block 43, the adjusting member 36 is connected by a link to the lever 17 and the normal position of the slide 32 aligns the pin 35 with a pin 40 connecting the lever 39 to the block 43. Movement of the lever 1 acts through the linkage to effect an equal movement of the lever 17. On depression of the pedal 7 the slide 32 is moved up to effect an overriding, displacement reducing, movement of the adjusting member 36 and lever 17. The block 28 may alternatively or, as shown additionally be connected by cables 10, 11 to brake actuating pedals 14, 15 which, on initial pedal depression, reduce pump displacement prior to actuating service brakes 12, 13. Individual actuation of either brake pedal 14 or 15 reduces pump displacement by one half whilst simultaneous actuation of both brake pedals reduces pump displacement to zero. The latter being effected by an interlocking system, Figs. 7, 8 and 10 (not shown), connecting the actuating cables 10, 11 to the block 28.