Clutch device between a shaft and a pulley and motor bloc suitable for a car with this clutch device

The device has autonomous controllable driving units for driving a shaft (14) by a pulley to prohibit driving of the shaft by the pulley when the pulley is turned at rotation speed lower than given rotation speed, and to allow driving of the shaft by the pulley when the pulley is turned at the rotation speed higher than the given rotation speed. The autonomous controllable driving units include connection units (50-53) between inertial masses (40-43) for allowing one of the inertial masses to drive the other inertial masses during radial spacing of the masses from an axis. An independent claim is also included for an engine block for a motor vehicle, comprising a thermal engine.