Automatic Transmission CVT - Mechanism & Function: Pulley&Chain

• The system consists of a primary pulley, secondary pulley, and chain.
• It presses the chain to the pulleys by the pressure generated from the hydraulic pressure chambers of the pulleys and thus generates friction force between the pulley banks and the chain to transmit the power.

Fig 1: Identifying Primary And Secondary Pulley With Status Before And After Stroking

Courtesy of SUBARU OF AMERICA, INC.

• It achieves continuously variable speed change by controlling the hydraulic pressures of the primary and secondary pulleys and thus changing the pulley widths. In addition, the larger transmission ratio intervals support both the drivability and the fuel economy.
• A guide rail is provided to both the tension side and the releasing side, which reduce the string vibration of the chain and resultant noises.

Fig 2: Identifying Pulley & Chain Related Components And Dimensions

Courtesy of SUBARU OF AMERICA, INC.