GB803066A - Improvements in or relating to mast lift trucks - Google Patents

Abstract

803,066. Lift trucks. SHARP, J. R., and KAYE, E. May 3,1955 [Feb. 8, 1954 ; Dec. 24, 1954], Nos. 3593/54 and 37341/54. Class 78 (3). In a lift truck the lifting carriage and movable guides are raised by a single pair of chains or cables each of which co-operates with pulleys mounted on the movable elements of a pair of oppositely-acting hydraulic rams. Rams 21, 25 (Fig. 3), are secured to the fixed guide 15 at 20, 24 and carry pairs of pulleys 23, 28, 29 which, together with pairs of pulleys 33, 34, mounted on the movable guide 16, co-operate with a pair of chains 30 which are anchored to the guide 15 and lifting carriage 17. In operation ram 21 is extended to raise the carriage nearly to the top of guide 16, whilst extension of ram 25 first moves the carriage into engagement with a stop 27 and then raises the guide through the carriage. An abutment 36 is provided to engage stop 27 to effect initial movement of guide 16. In a modification (Fig. 6) the original pulleys 33, 34 are dispensed with and a pair of pulleys 34 are journalled in a bracket secured to both the piston-rod or ram 25 and the guide 16. With this arrangement, both jacks are of the same effective crosssection and are connected in parallel to a common source of fluid pressure; the weight of section 16 and the forces exerted by chain 30 on the pulleys 23, 34 being such that on admission of fluid to the system ram 21 only extends until the carriage reaches the tops of guide 16, whereafter ram 25 extends, so simultaneously raising guide 16 and contracting ram 21. If desired, valves may be provided to connect the rams separately to the source of fluid pressure. Fig. 7 (not shown), illustrates a detailed construction of the arrangement shown in Fig. 6 which includes a horizontal ram adapted to tilt fork 18 relative to the carriage. Specification 780,487, [Group XXXI], is referred to.