Belt is sufficient to engage the input pulley to the output pulley, without torque converter/ clutch system. The objective is to make the CVT simple and cost effective.
At the time of belt engagement, input pulley driven by engine and output pulley driven by electric motor are rotating at same speed and direction. Since the input and output pulleys are rotating at same speed and direction, so less torque will be generated while engaging them. So Belt is sufficient to engage the input pulley to the output pulley.
Input pulley 1 is fixed pulley, it can be able to rotate on its own axis and can't move on axial direction when the engine drives it.
Input pulley 2 is movable pulley, it can be able to rotate and move on its own axis. The input pulley 2 is rotated by input pulley 1 or by belt; and the actuator controls its axial movement.
Output pulley 1 is movable pulley, it can be able to rotate and move on its own axis. The belt rotates the output pulley 1 and actuator controls its axial movement.
Output pulley 2 is fixed pulley, it can be able to rotate on its own axis and it transmits the power to the output shaft. It is connected with electric motor
Output pulley 2 shaft has 2 gears, which drives the forward and reverse gears in the output shaft.
Low speed: the electric motor drives the output pulley 2, which in turn drives the output shaft. The belt disengages the power flow from output pulley to input pulley as input pulley 2 is away from the engagement point. So the belt is not tight enough to transmit the torque to the input pulley.
Medium speed: the engine drives the input pulley 1, actuator pushes the input pulley 2 towards the input pulley 1. When it reaches the engagement point, belt start getting tighten after which input pulley transmit the torque to the output pulley 2.
High speed: both engine and electric motor drives together @ high-speed range.
Reverse speed: As like low speed range, the electric motor drives the output pulley 2, which in turn drives the output shaft (only difference is that synchromesh is engaged to the reverse gear).
Braking: we can be able to disconnect the power transmitting from input pulley to output pulley at the time of braking by moving the input pulley 2 to its belt disengagement position.
The belt is used like a clutch to engage and disengage the power from the engine to transmission and also is used to transmit the power from input pulley to output pulley.
The axially movable input pulley is used like a fork lever to push the belt to engage and disengage the power from the engine to transmission and is also used to variate the pulley diameter
Two different power sources can be fitted at input and output pulley side, since belt can able to connect/disconnect the power.