Speed reducing and torque transmitting mechanism

A speed reduction mechanism for transmitting torque less than a predetermined torque comprising:

• a first shaft;
• means for mounting the first shaft for rotation about a first axis;
• a first bearing surface having as a generatrix at least a portion of a radially extending straight line intersecting the first axis at a point and rotating about the point through 360.degree. at a constant angle with respect to the first axis;
• a cone having a surface in direct, unlubricated engagement with the first bearing surface along a line of contact which is coincident with the radially extending straight line which forms a genetraix of the first bearing surface, the cone having an apex which is substantially coincident with the point on the first axis about which the generatrix rotates;
• cone mounting means for mounting the cone to rotate about a second axis oblique with respect to the first axis and coincident with the axis of the cone, the second axis intersecting the point on the first axis about which the generatrix rotates;
• means for connecting the cone mounting means to the first shaft to rotate the cone mounting means about the first axis in a first direction, wherein the conical surface revolves in the opposite direction around the point of intersection to the first direction as the conical surface rotates about the second axis so that the conical surface rolls over the first bearing surface in progressive line contact therewith without slipping with respect thereto until a torque is applied thereto which is greater than the predetermined torque;
• a constant velocity joint connected to the cone at the apex thereof and aligned with the first axis;
• a second shaft connected to the constant velocity joint and extending in alignment with the first axis, whereby the second shaft rotates at a speed less than the first shaft upon rotating the first shaft but with higher torque than that applied to the first shaft, and
• means for adjusting the force with which the conical surface is urged against the first bearing surface to adjust the predetermined torque, wherein torque in excess of the predetermined torque will not be passed through the mechanism from the first shaft to the second shaft due to slippage between the conical surface and the first bearing surface.