GB706714A - An improved hydraulic power lifter, more particularly for agricultural tractors - Google Patents

Abstract

706,714. Hydraulic machines. MASCHINENFABRIK FAHR AKT.-GES. Nov. 22, 1949 [Oct. 7, 1948], No. 12768/51. Divided out of 29917/49 (as open to inspection under Sect. 91). Class 69 (2) In a hydraulic power lifter having a switching lever for initiating the lowering and raising operations, a disc sector or the like mounted on a rotary lifter shaft is provided with a fixed abutment which towards the end of the lowering or raising operation comes in contact with stops on the switching lever to return the lever and the control valve which is coupled thereto into the holding position. A lifter shaft 16, Fig. 6, is rotated by a piston 35d in a cylinder 4 through a crank 38, liquid supply to the cylinder being under the control of a rotary valve 40 operatively connected by a rod 7, Fig. 2, to a switch lever 6 rotatably mounted on the shaft 16. A sector 12 secured to the shaft 16 has a pin 25 which engages stops 31, 32 on the lever 6 in the lowered and raised position respectively to return the lever 6 and valve 40 to the hold position. The rod 7 is biased to the hold position of the valve 40 by a spring 35 and may be retained in the two working positions by a ball catch. A preselector lever 11 having an abutment 24 is rotatably mounted on the shaft 16 and has a tooth engagable with notches 26 on the sector 12 for driving the preselector lever. The abutment 24 can contact a projection 29 on the lever 6 to return it to the hold position before the lowering operation is completed. The lever 6 is rotatable about a pin 55 so that the projection 29 may be withdrawn from the path of the abutment 24 to complete the lowering operation without upsetting the adjustment of the lever 11. The outlet from the cylinder 4 to the valve 40 is through a restricted passage 43 to control the lowering speed.