US Patent 7811187 Continuously variable transmission

A continuously variable transmission has a primary pulley having a primary movable sheave that is capable of moving to change a groove width of the primary pulley, and a secondary pulley having a secondary movable sheave that is capable of moving to change a groove width of the secondary pulley. Endless flexible members are engaged with the primary pulley and the secondary pulley to transmit torque therebetween. At least one of the pulleys has a thrust applying mechanism that is capable of applying spring force and first fluid pressure force to the movable sheave of the pulley so as to narrow the groove width thereof and generating second fluid pressure force opposite to the spring force and the first fluid pressure force.