An infinitely variable or stepless mechanical speed changing mechanism for transforming a rotary output shaft speed of lower or higher speed than the input speed and respectively higher or lower output torque than the driving input torque. Interleaved stacks of relatively thin flexible laminates are keyed to the respective shafts with some freedom of interleaving accomodation and developing the required tangential tractive effort in the planes of the laminations by means of substantially dry non-viscous Coulomb friction forces due to the loading forces applied normal to the planes of the laminations on the stack ends in a direction to pinch together the interleaved laminations, and with said normal loading forces applied to the outer laminations in either input or output stacks, or in both, by means of loading ball-bearing like wheels whose convex outer surfaces roll with substantially no slip on said outer laminations.