GB2016409A - Hoisting structure for hoisting equipment - Google Patents

Abstract

A hoisting structure for hoisting equipment such as fork lifts has a hoisting cylinder-piston assembly which includes an outer cylinder (4), a hollow plunger (5) slidable in the outer cylinder and itself forming a cylinder, and a piston rod (7), slidable in the cylinder formed by the plunger, the hoisting structure comprising a stationary mast member (1), one or more extensible mast members (13), a stop (2) which is fixed relatively to the outer cylinder, and flexible hoisting means such as chains (10, 17), the arrangement being such that when pressure fluid is supplied to the common cylinder space (35) the load carrier (21) is first lifted off the ground by extension of the piston rod (7), while the telescopically movable mast member or members (13) remain in their retracted or lowered condition, until pulley wheel (9) on piston rod (7) has reached the stop (2), after which the one or several extensible mast members is or are extended by extension of the plunger (5), the load carrier being moved at a substantially uniform velocity relatively to the mast member (1) throughout this operating sequence. Where a plurality, e.g. two, of extensible mast members (13) are used, two alternative arrangements are described, in one of the which (Fig. 2, not shown) the outer cylinder (4) is fixed as in Fig. 1, while in the other (Fig. 3, not shown), the outer cylinder (4) follows up the movement of the piston rod (7) as a result of extension of the plunger (5). <IMAGE>