Improvements in or relating to Variable Velocity Power Transmission Devices

2160. Louis, E. S. Jan. 26. [Cognate Application, 4408/12.] Variable - speed bell gearing, suitable for lathes, comprises expanding pulleys having separable flanges 1, 2, Fig. 2, which coact with cam grooves or surfaces 5, 6 so as to be pressed into gripping engagement with a belt &c. with a force automatically proportioned to the effective tension in the belt for all diameters. The grooves 5, 6, which may be cut in a sleeve 3 secured to a shaft 4, are inclined in opposite directions, and are engaged by pins &c. 7, 8 projecting from the flanges 1, 2. As the diameter of pulley increases, the turning-movement for a given belt-tension increases, and therefore a less inclination of the grooves 5, 6 is necessary to keep the squeezing action of the pulley flanges constant. The grooves 5, 6 are therefore curved, being more nearly parallel to the axis of the shaft 4 at their outer than at their inner ends. The grooves 5, 6 may slope in the opposite way on the other side of the sleeve 3 to allow the pulley to drive also in the opposite direction. Gearing comprising a pair of these pulleys, controlled through rollers 27, 28 from a hand-wheel 31 is shown in Fig. 12.