GB1149351A - Masted lift trucks - Google Patents

Abstract

1,149,351. Masted lift trucks. CONVEYANCER FORK TRUCKS Ltd. 20 July, 1966 [21 April, 1965], No. 16772/65. Heading B8H. [Also in Divisions D1 and E2] A masted lift truck has cams 28, 29 which, if lift chains 16, 17 fail, are urged by springs 33, 34 into engagement with a bar 12 to arrest descent of the load. The mast comprises an outer section 1 in which slides an inner section 2, the section 1 being secured to the truck body. The section 2 comprises two spaced I- sections interconnected at the top and bottom by cross-bars 3, 4. An hydraulic ram 5 has its cylinder secured to the truck body at 6, and its pistonrod 7 has an end fitting 8 carrying pulleys 9, 10. The fitting 8 abuts a plate 11 on the bar 3. The bar 12 is secured to the bars 3, 4. A carriage 13 is slidably mounted on the mast section 2 and the chains 16, 17 extend from anchorages on the carriage round the pulleys 9, 10 to anchor rods 18, 19 secured to the truck body at 18A. The carriage 13 carries lifting forks 24 by means of a scissor type mechanism 25 operated by hydraulic rams 26. A plate 27 is secured across the back of the carriage 13 in front of the bar 12 and has secured to it another plate 30 disposed behind the bar 12, the cams 28, 29 being rotatably mounted between the plates 27, 30. Brackets 31, 32 are respectively secured to the cams 28, 29 and the springs 33, 34 are connected between the brackets 31, 32 and the plate 27. A cable 35 which restrains the springs 33, 34 from rotating the cams 28, 29 into engagement with the bar 12 extends from the bracket 31 via conduits 36, 37, the pulley 9, a conduit 21, the pulley 10 and conduits 38, 39 to the bracket 32. In operation, if the chains 16, 17 break, the cable 35 takes the weight of the carriage and will either break or an end thereof will pull out of its fastening. The springs 33, 34 will no longer be restrained and will engage the cams 28, 29 with the bar 12. The cams 28, 29 may be mechanically coupled for simultaneous rotation. If a mast section is raised by the intermediary of chains, similar means may be provided to arrest descent of that section. The surfaces of the cams 28, 29 may be serrated.