Patent GB-676191-A (GB)
Title: Improvements in hoists
IPC: B66B9/16
Filed: 1946-06-13
Abstract: 676,191. Hoists. DICK, J. A. June 13, 1947. [June 13, 1946] No. 17751/46. Classes 78 (iii) and 78 (v). [Also in Group XXXII] A hoist comprises a chassis having road wheels thereon, a mast or framework supported on the chassis so as to be movable from an inoperative to an operative, and approximately vertical, position, said mast or framework being adapted to have a load carrying platform raised or lowered thereon when in the operative position, and said chassis being arranged to be supported directly from the ground when the hoist is' in operation. In the embodiment shown, the hoist comprises a chassis 10 on which is pivotally mounted a mast 22 along which a platform 24 is raised or lowered by a cable 30 connected to a winch drum 15. This drum is normally driven by a friction pulley 13 engaging its friction driving surface 14, the'pulley being driven through a chain drive by an internal combustion engine 12. The winch shaft is mounted in eccentrics 16 and the winch is normally loaded by a weighted lever 17 so as. to be out of engagement with the pulley 13 and .in engagement with a brake shoe 18. The chassis 10 is provided with holes 38 to receive the axle of a pair of road wheels whereby when the mast is pivoted downwards on to the chassis, the chassis can be turned from the position shown in Fig. 1 to that shown in Fig. 5, ready for removal to another site. In this latter position the centre of gravity of the hoist is approximately over the wheel axle. To erect the hoist at its new location, the chassis is first turned about the wheel axle so as to bring a part of the chassis into contact with the ground and then turned about this point of contact to the position shown in Fig. 1. The mast is then pivoted to its vertical position and struts 29 attached to the chassis. Jacks 28 on arms 26 extending laterally from the mast ensure stability. If after erecting the mast, it is found desirable to move the hoist a short distance, this is effected by positioning the axle of the wheels 39 in holes 40, Fig. 5, which are close to the centre of gravity of the hoist when in its erected position. The chassis is then raised by the jacks 28 to enable the wheels to be placed on the axle, then lowered on to the wheels. To raise the platform 24, a rope 36 is pulled hard by the operator so as to pivot a lever 34 on the mast and through a rope 35 pivot the lever 17 so as to turn the eccentrics 16 and move the winch drum into engagement with the pulley 13. To lower the platform, the rope 36 is pulled not quite so hard so that the drum is just freed from the brake shoe 18. Movement of the hoist beyond its limiting position is prevented by the lever 34, since the platform when it reaches the level of the lever 34, pivots the lever so as to release the lever 17 and allow it to fall and disconnect the winch from the engine drive. The lever 34 is mounted on a member 37 which may be secured at any desired point on the mast. Alternatively, a series of fixing points for the lever pivot may be provided. The hoisting cable 30 passes successively over a a pulley 31, at the foot of the mast, a pulley 32 at the head of the mast, a pulley 33 mounted on a bracket 23 on the platform 24, a second pulley 32, at the head of the mast, and a second pulley 33, attached to the platform, finally being anchored to the head of the mast.