GB181963A - Improvements in operating mechanism for cranes and overhead travellers - Google Patents

Abstract

181,963. Cornes, T. r. June 10, 1921. Jib cranes; overhead travellers and transporters.-In a jib crane or overhead traveller of the kind in which the luffing or traversing drum C and the hoisting-drum A are driven from the same or different main power shafts through separate driving-trains but may be connected by gearing to effect luffing or traversing with horizontal travel of the load, the driving-train for the luffing drum 0 comprises a worm-wheel C<3> fast with the drum and either irreversible or provided with a brake. The drive for the luffing- drum is reversible, and the hoisting-drum A may be driven from the main power shaft directly or through gearing on the luffing-drum. The power shaft B drives a spur-wheel A' continuously, and either of two bevel-wheels C<7>, C<8> may be connected to the shaft B by operating a clutch lever E, in order to drive the luffing-drum C in either direction through the worm-gearing C<3>, C<4>. The hoisting-drum A may be moved longitudinally by a lever D so as to engage the wheel A', to be held in the free mid-position, or to engage a spur-wheel A<6> geared to a wheel C<2> on the luffing-drum. The luffing-drum may be of the fusee type, so that when the luffing and hoisting-drums are geared together through the wheels A<6>, C<2> the load is moved horizontally. For hoisting, the lever E is in mid-position, the wheels C<7>, C<8> are free on the shaft B, and the drum C is held stationary either by the worm drive or by an automatic brake; the lever D is moved to engage the hoisting-drum A with the wheel A<4>. For lowering, the drum A is moved into engagement with the wheel A', the clutch surfaces being used for braking. For luffing with horizontal travel of the load, the drum A is engaged with the wheel A<6>, and the lever E moved to engage one of the wheels C', C' with the driving shaft. An interlocking device for the levers D, E is arranged so that when the crane is loaded with the lever E in mid-position and the luffing-drum stationary, the lever D can be moved in either direction for hoisting or lowering, while the lever E can only be moved for rotating the luffing-drum in either direction after the lever D has been moved to the left to engage the drum A with the wheel A<6>. In this latter position of the two levers, the lever D cannot be moved back until the lever E has been brought back to mid-position and the wheels C, C<8> disengaged from the driving shaft. This interlocking gear is brought into action when the crane is loaded, by the tension in the luffing-rope moving the worm C<4> endwise on its shaft. In a modification, the gearing from the shaft B to the worm wheel C<3> is omitted, and the luffing- drum is driven by a separate power unit G having a reversing-switch interlocked with the lever D.