Double acting secondary sheave servo for a continuously variable transmission

A continuously variable transmission system to provide transmission of torque from a torque input means to a torque output means, comprising:

• rotatable input and output shafts;
• drive means for drivingly coupling said input shaft with said output shaft, said drive means including a first variable pulley rotatable with said input shaft, a second variable pulley rotatable with said output shaft, and a belt means coupling said first and second variable pulleys, each of said first and second variable pulleys having a fixed sheave and a movable sheave;
• first biasing means for continuously biasing together said fixed and movable sheaves of said first variable pulley, second biasing means for continuously biasing together said fixed and movable sheaves of said second variable pulley;
• and
• said second biasing means including a plurality of fluid chambers having fluid access to a source of pressurized hydraulic fluid, said plurality of fluid chambers including first, second and third fluid chambers, said first chamber being in fluid communication with said hydraulic fluid source, addition and exhaustion of fluid from said fluid chambers being effective to cause relative movement of said movable sheaves,
• said movable sheave of said second variable pulley being operatively positioned for movement from a first position to said second position corresponding to movement from a position proximate to a position distal from said fixed sheave of said second variable pulley,
• said movable sheave of said second variable pulley including a first fluid conduit, positioning of said movable sheave in said first position being effective to permit communication of fluid between said first fluid chamber and said third fluid chamber through said first fluid conduit.