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All inertial continuous/infinite variable transmissions (CVT-IVT) need of a rectifier. This is due to the fact that this type of CVT-IVTs should transform, in some way, the ratcheting motion into a unique direction of rotation in order to be transmitted to the kinematic chain of the vehicle transmission system. The choice of the rectifying system and the characteristics of the components heavily depend on the motion to be rectified and on the oscillating mechanism generator. The current rectifier systems included in inertial CVT-IVTs use freewheels to transform the oscillating movement. The use of freewheels has serious limitations for tourism and industrial vehicle applications, regarding the upper bounds of conforming to two working situations: i) high torque at low speed, and ii) high speed at a relatively low torque.

Currently, continuously variable transmission (CVT) is a topic of special interest as it allows the vehicle to have the engine working at its optimum regime (either minimum or maximum power consumption as required) remaining unaltered despite the changes in speed and the torque required on the drive wheels during operation. There is a particular group of CVTs with special characteristics: dynamic type CVTs. In these, in addition to acting on a control element, as in the rest of the kinematic type transmissions, the gear ratio also depends on the external conditions to which the transmission is subjected, that is, the transmission ratio is also determined by other variables such as the angular velocity of the input shaft and the load torque exerted on the output shaft. This paper reviews the most representative dynamic CVTs and torque converters (TCs) stating the basics of their functioning.