GB604934A - Transportable lifting jack - Google Patents

Abstract

604,934. Lifting-jacks. NIEDERHAUSER, A. Aug. 8, 1945, No. 20303. [Class 78 (iii)] In jacks of the kind in which two parallel lifting arms 11, Fig. 1, are connected at their free ends by a pivoted load engaging member 13 and are pivoted at their lower ends to sleeves 10, Fig. 5, mounted on threaded spindles 2, and are connected also by pairs of pivoted links 12 to the frame 1, an additional upward movement is imparted initially to the free ends of the arms by a pair of pivoted members 19 which are actuated. by the spindles 2. The upper ends of the members 19, Fig. 8, bear against rollers 56 mounted in a cross-member 18 connecting the arms 11 and their lower ends are connected by pivoted links 22 to a member 23 secured to a thrust beam 24. Thrust bearings 54 are placed between the beam and nuts 53 mounted on the spindles 2. Chain-and-sprocket gearing connects the spindles 2 to the shaft of an electric motor 7 which shaft can be rotated by a crank 43 if the current fails. Limit switches are provided for breaking the motor circuit when the arms 11 reach their upper and lower positions, but the arms can be stopped in any intermediate position by pressing a stop button on the switch box. This box contains also a thermal switch which acts as a safety member in case of overload. The frame 1 is supported by wheels 27 and a castor wheel 28. The wheels 27 are supported by arms 36 which are pivoted in bearings 38 on the frame. The arms 36 are connected by links 39 to a handle 34 which is pivoted at 30 to the frame and provided with a foot 31. When the handle is turned in the direction of the arrow, Fig. 5, the part 35 bears on the head 40 of the pin carrying the wheel 28 and the arms 36 are turned by the links 39 to raise the frame from the ground. Means is provided for locking the frame in this position.