Variable speed drive for a continuously variable transmission

摘要

A friction ring variable speed drive with a continuously variable transmission ratio. A concavely curved first transmission element is rotatable around a first axis of rotation and a convexly curved second transmission element is rotatable around a second axis of rotation. The first and second transmission elements receive between them a segment of the circumference of a transmission ring. An adjusting device presses the transmission surfaces against the circumferential surfaces of the transmission ring for frictional transmission of torque between the transmission elements. The position of the transmission ring relative to the axes of rotation is variable by means of the adjusting device. A contact pressure device is provided for imposing a contact pressure between the transmission surfaces and the transmission ring, and the contact pressure increases as the transmitted torque increases.