A shaft-hub connection system with angular play for the bidirectional transmission of driving torque, comprising a shaft extended along a main axis, a hub provided with a hole inside which said shaft is at least partially accommodated and means for connection with predefined angular play which are interposed between said hub and said shaft for the bidirectional transmission of the driving torque about said main axis and are adapted to alternately assume at least one configuration for free relative rotation between the shaft and the hub about the main axis, a first active configuration for transmission of the torque between the shaft and the hub in a first direction about the main axis and a second active configuration for transmission of the torque between the shaft and the hub in a second direction, which is opposite with respect to the first one, about said axis, these configurations being angularly mutually offset about the main axis, characterized in that said connection means comprise at least one functional assembly which comprises a slot associated with the outer side wall of said shaft in which a corresponding coupling element is accommodated so that it can move and is adapted to assume alternately a first position, in which it is retracted within said slot, a second position, in which it protrudes partially with respect to it along a first orientation, and a third position, in which it protrudes partially with respect to it along a second orientation, elastic compression means interposed between said slot and said coupling element for the movement of said element from the first position to the second or third position, a first seat and a second seat (11, 12) for the abutment of said coupling element, respectively in the second and third positions which are associated inside the hole of said hub and are angularly offset about said main axis, in the first position the coupling element being completely accommodated within the slot in order to maintain the configuration for free relative rotation and in the second or third position the coupling element protruding partially from said slot in order to engage respectively the first seat in the first active configuration or in the second seat in the second active configuration. a shaft extended along a main axis, a hub provided with a hole inside which said shaft is at least partially accommodated and means for connection with predefined angular play which are interposed between said hub and said shaft for the bidirectional transmission of the driving torque about said main axis and are adapted to alternately assume at least one configuration for free relative rotation between the shaft and the hub about the main axis, a first active configuration for transmission of the torque between the shaft and the hub in a first direction about the main axis and a second active configuration for transmission of the torque between the shaft and the hub in a second direction, which is opposite with respect to the first one, about said axis, these configurations being angularly mutually offset about the main axis, characterized in that said connection means comprise at least one functional assembly which comprises a slot associated with the outer side wall of said shaft in which a corresponding coupling element is accommodated so that it can move and is adapted to assume alternately a first position, in which it is retracted within said slot, a second position, in which it protrudes partially with respect to it along a first orientation, and a third position, in which it protrudes partially with respect to it along a second orientation, elastic compression means interposed between said slot and said coupling element for the movement of said element from the first position to the second or third position, a first seat and a second seat (11, 12) for the abutment of said coupling element, respectively in the second and third positions which are associated inside the hole of said hub and are angularly offset about said main axis, in the first position the coupling element being completely accommodated within the slot in order to maintain the configuration for free relative rotation and in the second or third position the coupling element protruding partially from said slot in order to engage respectively the first seat in the first active configuration or in the second seat in the second active configuration.