An All-electric Mobile Crane
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ECENTLY introduced by Cromp ton Parkinson, Ltd., Astor House, Aldwych, W.C.2, and C. H. Johnson (Machinery), Ltd., the 10-cwt. Mynne electric runabout crane has been developed for operation by the class of labour normally employed for heavy handling. Special attention has been given to simplicity of control and safety by making the working parts robust and fool proof, at the same time providing accessibility.
Electricar Chassis The unit consists of a jib crane mounted on a 2-ton Crompton Parkinson Electricar chassis. The latter is of a type specially designed for manmuvrability, with a speed of m.p.h., and it has a long wheelbase to ensure complete stability. The maximum overall height of the jib is 15 ft. 6 ins., and the minimum clearance height 6 ft. 9 ins. Maximum ground to hook height is 13 ft.
When a load of 10 cwt. is being lifted the maximum permissible radius of operation is 9 ft., but the radius increases with lighter loads, and 6 cwt. can be handled at a radius of 13 ft. Safe load and radius indicators of the drum type are fitted to the carriage king posts to be easily visible from the operator's platform. T h e hoisting speed is 60 ft. per minute.
The crane including treek weighs 2 tons 12 cwt. Both the lattice-type jib and the carriage are of welded con struction. Th:-; hoisting machinery is enclosed in the carriage. A p. motor drives the hoist through a directly coupled, totally enclosed, fan-cooled worm-reduction gearbox.
Hoisting and lowering are controlled by a reversing drumtype controller with three steps in each direction.
A 320 amp.-hour battery provides power for both the hoist motor and the truck motor. The battery is in two sections, fitted into sliding carriages.
The crane can readily be removed from the truck. which can then be used separately.. The • hoist motor is connected to the control cubicle hrough a special withdrawable plug, so that no permanent connections have to be undone,