Abstract: The present invention relates to a speed reduction apparatus for globoid worm gears. The speed reduction ratio of the engaged worm globoid worm gear and worm wheel is defined as the ratio of the rate of rotation of the globoid worm gear about its axis to the rate of rotation of the worm wheel about its axis. The structure of the present invention speed reduction apparatus is defined by the distance between the axes of rotation of the worm wheel and globoid worm gear and the spacial and speed relationships between the globoid worm gear and the surfaces of the cutting tool employed to generate the worm gear.

Abstract: A method of modified gear cutting of a globoid worm gear. A worm wheel gear cutting tool employs a conical cutting surface which is substantially the same as the conical surfaces of the teeth of a cooperating globoid worm wheel. The worm wheel is the reciprocal image of the conical cutting surface of the tool. A worm gear is cut by imparting to the cutting tool a motion defined both by the distance between the axis of the worm gear to be cut and the axis of rotation of the cutting tool as well as the speed reduction ratio which constitutes the ratio of the speed of rotation of the cutting tool to the speed of rotation of the worm gear.

Abstract: An improvement of a globoid worm gear generating method based on the "basic member gear theory" and the "secondary action theory" both proposed by the same inventors is disclosed. In one form, the surface of a globoid worm generating tool is defined as the tooth surface of an intermediate gear by a conical surface whose semivertical angle .UPSILON., 0.degree..ltoreq..UPSILON..ltoreq.90.degree.. In another form, the surfaces of a globoid worm gear generating tool are defined by two conical surfaces whose semivertical angles are equal and satisfy the above condition and whose major axes as well as bottoms are coincident with each other so that both tooth surfaces of a worm may be simultaneously generated.