Stepless speed change gear

A stepless speed change gear comprising:

• an input member;
• an output member coaxial with the input member;
• a plurality of conical rollers, each roller having a conical surface, a substantially flat surface at the base of the conical surface, and a concave surface extending downwardly from the substantially flat surface;
• first means for changing speed of the output member, frictionally engaging the conical surface of the conical rollers, and being movable in a common axial direction of the input member and the output member;
• second means frictionally engaging the substantially flat surface of the conical rollers, one of the first means and the second means being rotationally fixed, the other of the first means and the second means being connected to the output member;
• third means frictionally engaging the concave surface of the conical rollers, connected with the input member, and operable to wedge the conical rollers between the first means and the second means;
• and
• means for generating contact pressures between the conical rollers and the first, second and third means, operable to generate a force transmitted through the third means.