Patent GB-536996-A (GB)
Title: Speed change device
IPC: F16H9/06
Filed: 1940-03-06
Abstract: 536,996. Change-speed gearing. FALTERMAYER F. W. March 6, 1940, No. 4226. [Class 80 (ii)] Change-speed gearing, particularly for machine tools, comprises an endless belt cooperating with stepped pulleys on the driving and driver. shafts, means for moving the pulleys relatively to slacken the belt, and means for holding the slackened belt clear of the pulleys, the holding-means being shiftable laterally to bring the belt into position for engaging the selected pair of pulley-steps. In the mechanism shown in Figs. 2 and 4, a shaft 11, mounted in bearings 18, 19 on a base 20, is provided with stepped pulleys 14 which are connected by a flat or V belt 15 to stepped pulleys 13 on the shaft 10 of a motor 12. A carriage 21 supporting the motor is mounted on rods 22, 23 which can be moved towards or away from the shaft 11, to slacken or tighten the belt, by means of a crank 31 on a shaft 29 geared to a pinion which engages a rack 26 on the carriage. A dog 32 for holding the carriage in normal position is secured to a spring-urged sleeve 33 which is provided with a finger-piece 37 for releasing the dog. A belt shitter or holder 39 comprises semi-circular endpieces 40, 41 connected by telescopic channelpieces 42, 43. Pairs of rods 49 secured to the end-pieces are connected to slides 52 and pass through slots 50, 51 in arms 46, 47 which are secured to brackets on the base 20 and carriage 21 respectively. The arms are parallel to the slope of the pulleys. The belt-shifter is moved laterally by means of a slide 60 which is mounted on a rod 58 and is operated by a handlever 61. The slide is provided with channelpieces 64 which engage the belt-shifter and have lugs 65 for engaging the belt. On release of the catch 32 and movement of the crank 31, the carriage 21 is moved towards the shaft 11 the parts 42, 43 telescope, and the belt slackens and bulges into engagement with the channel-pieces of the belt shifter. The hand lever 61 is then rocked to move the slide 60 and consequently the belt-shifter to the front or rear to bring the belt into register with the selected steps of the pulleys. The slots 50, 51 cause the belt-shifter to move in a path parallel to the slope of the pulleys, the arrangement enabling a shorter belt to be employed than would be required if the belt-shifters moved in the direction of the pulley axes. After the belt has been registered with the selected steps, the crank 31 is moved to return the carriage 21, and the belt tightens and engages the steps. The hand-lever 61 is provided with a catch for engaging notches in a plate 72, and is set with reference to a scale 76. To prevent operation of the hand-lever before the carriage 21 has been moved towards the shaft 11, the carriage is provided with a rod 77 which passes through holes 81 in a plate 80 on the slide 60 and is formed with a neck 79 arranged, when in register with slots between the holes, to permit movement of the slide. To permit removal of the belt, a stop 84 is detached, and the beltshifter is moved by means of the hand-lever 61 into the extreme forward position. When a multiple belt is employed, the inner members 43 of the belt-shifter may be provided with guideprojections for strands of the belt, or the strands may be unitary, or united by a backing. Instead of arranging the shaft 10 to move laterally, the shaft 11, or both shafts may be so arranged.