GB1421351A - Load-lifting mechanism for a lift truck - Google Patents

Abstract

1421351 Fork lift trucks KNICKERBOCKER CO 4 May 1973 [8 May 1972] 21193/73 Heading B8H Telescopic mast for a fork lift truck comprises a lower fixed section 28, an intermediate section 30, an upper section 32 and a load carriage 22 supporting forks 24. An hydraulic ram 34 is mounted on the lower section and its piston-rod 76 mounts pulleys 80 about which chains 33 pass. One end of the chains 33 is secured to the cylinder 74 of the ram and the other end is secured to a slide 60 movable along rods 64 mounted on the intermediate section 30. Further chains 35 pass over pulleys 86 mounted on the slide and are connected at one end to rails 36 on which the slide moves and at the other end to a bar 70 movable along the upper section 32 to engage with and raise the lift carriage 22. A latch 130 mounted on the upper section 32 engages a roller 180 on the lower section 28 during the raising of the lift carriage to restrain the upper section 32 from movement. A cam 128 on the carriage engages the latch as the carriage approaches its upper position on the upper section to release the upper section from the lower section and to lock the carriage with the upper section. Simultaneous with the carriage reaching the said upper position the bar 70 abuts a stop 90 on the cylinder 74 and the slide 60 abuts a stop 66, thus further extension of the ram acts through the chains 33 to raise the intermediate section and through chains 35 to raise the upper section and hence the lift carriage. A pin (71), Fig. 4 (not shown), on the bar 70 engages an indented ball (93) in the stop 90 to retain the bar 70 in contact with the stop during the extension of the mast and also to restrain the ram from tilting forward due to the loading thereon. A bracket 82 on the cylinder 74 engages with hooks (222), Fig. 9 (not shown). In the intermediate section in the retracted position of the mast to prevent similar tilting of the ram. In an alternative embodiment, Fig. 19 (not shown), the lower section (28) is mounted to telescope within a base section (314) and the ram (340) has an additional downwardly extending piston-rod (302) carrying pulleys (304) around which cable (306) passes. The cable being secured at opposite ends to the cylinder (74) and the base section (314). In a further embodiment, Fig. 20 (not shown) a fourth mast section (402) carries the original mast and a chain (406), secured at opposite ends to the section (402) and the intermediate section (30), passes around a pulley (404) mounted on the cylinder (74) of the ram (34).