GB883643A - Improvements in automatic control systems for tools carried, semi-carried or trailed by a tractor - Google Patents

Abstract

883,643. Tractor power lifts. SAME SOC. ACC. MOTORI ENDOTERMICI. Nov. 24, 1959 [Sept. 23, 1959], No. 39831/59. Class 79(1). In a tractor hydraulic power-lift mechanism wherein an implement may be automatically held at a predetermined position relative to the tractor, the pump for the hydraulic system is operated from the tractor engine independently of the tractor gears and is housed in a casing separate from the tractor gear casing and not in communication therewith. The hydraulic ram, control valve therefore, and pump are housed as a unit in the container which may be attached to the casing of the gear mechanism of the tractor. The tractor power lift linkage comprises the lower arms 5, which are pivoted at 6 to levers 7 attached at their lower ends to a rotatable shaft 8 and pivoted at their upper ends to rods 11. Each rod 11 can slide between washers 12 and 13, Fig. 2, separated by a spring 16 and abutment members 10 and 90 cause one or other of the washers to move with the rod according to -its direction of movement. The lower arms 5 are attached by links 17 to power lift arms 18 which are attached to a shaft 40 rotated through a lever 39 by a hydraulic ram 37 to which fluid under pressure may be supplied by the pump 20 driven by the tractor engine. The pump has two opposed pistons and has a delivery side and a suction side which may be connected selectively to the ram 37 by a valve 43 which is connected by linkages to hand levers 21 and 22. The valve 43 also has a position whereby both delivery and suction conduits are closed. The valve 43 is displaced by a lever 49 pivoted at 50; the hand lever 22 is connected to lever 49 through the rod 60 and the hand lever 21 is connected to 49 through rod 57 and bell crank lever 53, one arm of which carries a roller 55 which bears upon a cam surface 56 carried by levers 39. The lever 49 is also connected by links 62, 25, 24 to the rod 11. The hand lever 21 is used for direct control of the hydraulic power lift system, for raising and lowering the power lift arms; the hand lever 22 is used for obtaining a predetermined depth-for a given setting of the lever 22 the lift arms will descend until by action of the cam 56 and bell crank 53, the valve 43 is shut off. Automatic depth control of the implement is obtained through links 62, 25, 24, 23 dependent upon reciprocations of the rod 11, the bell crank lever 53 being moved to an inoperative position. In a modification, Fig. 3, the implement is partly supported by a wheel 71, the position of which relative to the implement is adjusted from the power-lift arm 18 through a flexible cable 73. In a further modification, Fig. 4, the implement is partly supported by wheels 80, 77 attached to a link-work connected to a hydraulic jack 79 actuation of which from the power lift arms determines their position relative to the implement.