GB652116A - Improvements in or relating to variable speed transmissions - Google Patents

Abstract

652,116. Variable-speed gearing. STEVENS, A. H. (Cincinnati Milling Machine Co.). May 4, 1948, No. 12219. [Class 80(ii)] In a milling or other machine wherein a spindle 11 is mounted in a quill member 12 axially adjustable by means of a rack 21 and worm wheel 22 controlled by a spindle 26, the other end of the spindle 11 is slidably carried in a rotatably m o u n ted sleeve 33 and is normally driven by the latter through a dog clutch 45 irrespective of the axial adjustment of the spindle. A stepped pulley 65, splined on sleeve 33, is driven by a belt 73 from a stepped pulley 59 on the shaft of a motor 47, the pulley 65 being moveable axially by fork on a rod 76 moved through rack and pinion gearing 79 by a lever 80 having a pin to engage in any one of three holes 83, 84, 85, so as to increase the number of speeds at which the spindle 11 may be driven through the clutch 45. The motor 47 is carried by a frame 49 pivoted on a shaft 50 and carrying a pivoted nut member 52 engaged by a screw 55 operated by a hand wheel 57, whereby the motor can be raised or lowered to adjust the tension in the belt during speed changes. Gears 42 and 103, integral with the sleeve 33 and spindle 11 respectively, co-operate with a back gearpair 100, 102 slidable under the control of a lever 89, the lower arm of which controls the clutch 45 and which is operated by a bell-crank lever 93. In the normal position shown in Fig. 1, a pin carried by the lever 93 engages a hole 97, the clutch 45 being engaged and the back gear disengaged. By turning the lever 93 so that the pin engages a hole 98, the clutch 45 is disengaged and the gears 100, 102 mesh with the gears 42, 103, the gear 102 being wide enough to mesh with the gear 103 irrespective of the axial adjustment of the spindle. The number of available speeds is thus doubled.