GB564781A - Improvements relating to milling machines, lathes and other electro-motor driven machine tools - Google Patents

Abstract

564,781. Variable - - speed gearing. CASH, J. June 8, 1943, No. 9182. [Class 80 (ii)] [Also in Group XXII] In a lathe, milling-machine or other machine tool having stepped pulleys on a headstock and countershaft which is driven by an electric motor, the motor and countershaft are carried by a plate which is slidable to facilitate belt changing for varying the machine spindle speed. As applied to a milling-machine, the stepped headstock pulleys 6 are belt driven from the countershaft pulleys 7 which, together with gearing 11 and motor 9, are carried by a plate 13a slidable in guides on the machine pillar 4. Vertical movement of the plate is effected by a disc 18a rotatable on a pivot 4c on the pillar by a handle 18b and having an eccentric groove 18 acting on a roller 13c carried by the plate 13a, the weight of the plate &c. being partly balanced by springs 14 to assist in raising it. In operation, after stopping the motor, the plate is raised to allow the operator to insert his hand in the pillar to move the belt onto the required pulleys, after which the plate is lowered until the desired belt tension has been obtained and is then locked by a hand-operated nut 17c acting on a bevelled jib on one of the guides for the plate. The countershaft is supported by a bearing 12 on a bracket 13 projecting from the plate 13a through an aperture 4a in the pillar, and an oil pump 19 driven from a pulley 20 on the countershaft may be mounted on the bracket. The hand aperture in the pillar 4 for giving access to the belt may be provided with a hinged cover which is locked in the closed position unless the motor starter is switched off.