Cone Pulleys

In machine tools operating by rotary motion of tool or work, to preserve a uniform speed of cutting at the periphery of circles of varying radius, there must be provision to vary the number of revolutions of the driving spindle of the tool. In belt-driven tools, this is done by having pulleys of different diameters on the driving shaft, with a complementary series or nest on the shaft of the tool. The same belt may be made to drive from a large pulley to a small one at one extreme, and from a small to a large one at the other extreme, with intermediate steps and velocities. For a cro ed belt between the two shafts, the tension of the belt on any pair of pulleys of the cone will be constant if the sum of the radii of the two pulleys in any pair is constant; for the open belt, the steps are computed from the half sum and half difference of the pulleys on each side of the one being calculated.