GB639146A - Improvements in or relating to hydraulic power lift systems for tractors or the like - Google Patents

Abstract

639,146. Agricultural implements. INTERNATIONAL HARVESTER CO. OF GREAT BRITAIN, Ltd. June 17, 1947, No. 15922. Convention date, Sept. 21, 1942. [Class 6 (i)] [Also in Group XXIX] In a hydraulically operated power lift for a tractor the limit of movement of the power lift in one direction is determined by a fluid-pressure-operated adjustable stop means. The tractor is fitted with four hydraulic cylinders the two cylinders on one side of the tractor working independently of those on the other side, the operation of the two cylinders on one side being herein described. Oil is pumped to a chamber 44<SP>1</SP> from which the oil is normally exhausted through an orifice 74. A hand-lever engages a lever mounted on a shaft 51 on which is secured a lever 50 forked at one end to engage a sleeve 48. This sleeve has two slots 78 and 79 which co-operate with a passage 80 leading to an auxiliary cylinder 100 mounted at the end of the front cylinder 28. The stop piston 101 of this cylinder 100 has a rod 102 projecting into the front cylinder. The other end of-lever 50 engages a latch 56 which engages at one end a plunger 58 and at the other end a cup 59 covering a spring-urged ball valve 62. The shaft 51 is spring-urged to move lever 50 to a neutral position where the sleeve 48 is situated so that passage 80 lies midway between the slots 78 and 79. To raise the implements the hand-lever is operated to move the lever 50 so that the sleeve 48 closes orifice 74 in which position the lever 50 will be engaged by latch 56. Pressure builds up in the chamber 441 and opens ball valves 85, 86 to allow oil to flow into the front and rear cylinders. When the pistons reach the end of their stroke sufficient pressure will build up to unseat the ball valve 62 and raise cap 59 releasing the latch 56 and allowing the lever 50 to return to its neutral position. To lower the implements-the lever 50 is moved so that a member 94 pivoted thereon first contacts a push pin 96 and then a pin 961, which opens valves 85, 86 in succession. To adjust the depth of the front implements the lever 50 is moved to bring the slot 78 in sleeve 48 into alignment with the passage 80 in which position orifice 74 is closed causing the implements to be raised, oil also flowing into cylinder 100 to move the stop piston 101 in step with the main piston, the latch 56 being unhooked. On release of the hand-lever it will be returned to neutral by the spring on shaft 51, closing the passage 80 and retaining the stop piston in its new position. A similar operation adjusts the main piston and stop piston in the opposite direction. The mechanism for each set of pistons is operated either singly or jointly by the hand-lever. The depth of the rear tools may be adjusted by a hand-lever, connected to the rear piston rod, which co-operates with a sector connected to the lifting arm of the rear tools.