GB1200148A - Improvements in or relating to load lifting apparatus - Google Patents

Abstract

1,200,148. Masted lift trucks. TOYODA AUTOMATIC LOOM WORKS Ltd. 1 Nov., 1968 [7 Nov.. 1967; 14 Dec., 1967], No. 51848/68. Heading B8H. In a masted lift truck, the lifting carriage and movable mast section are each provided with pairs of upper, middle and lower guide rollers mounted for rotation about parallel areas and arranged to resist lateral thrust caused by eccentric loading. As shown, the lifting carriage 15, 17 is provided with guide rollers 21, 22, 23 engaging the movable mast uprights 7, and the channel of each upright 7 is formed by forward and rear flanges 7a, 7b, extending from a web. A curved rolling surface 7c is formed at the inside corner between the rearward flange 7b and the web and has the same radius of curvature as the periphery of the rollers. A supporting surface 7d is formed on the web in continuation of the surface 7c. The upper rollers are prevented from contacting the surfaces 7d by retaining rings 25, but the lower rollers 23 are adjusted laterally by shims 26 so that they contact the surfaces 7c. The middle rollers 22 are of smaller diameter than the upper rollers 21 so that they do not contact the forward flanges 7a until the upper rollers 21 are raised above the uprights 7. The surfaces 7c, 7d extend downwardly from a point a predetermined distance from the upper end of the uprights. Second curved surfaces and supporting surfaces 7d<SP>1</SP> are provided in the other upright inside corner and extend upwardly from the above point. In operation, when the lifting carriage is raised from its lowered position, the upper rollers 21 engage the forward flange 7a and the lower rollers 23 engage the rearward flange 7b, the curved surface 7c and the supporting surface 7d. The middle roller 22 on the side on which an eccentric load is supported, engages the surface 7d and rotates in the same direction as the lower rollers, and the other middle roller does not engage the adjacent upright. As the lifting carriage approaches its uppermost position, the middle roller passes from the surface 7d to the surface 7d<SP>1</SP> adjacent the forward flange and its direction of rotation is reversed. When the upper rollers 21 project above the uprights 7, the middle rollers 22 engage the forward flange 7a and adjacent curved surface. The fixed uprights are shaped similarly to the uprights 7 and are engaged by upper, middle and lower rollers mounted on the uprights 7, Figs. 12-14 (not shown).