Uncoupling device, particularly for universal joint transmissions

An uncoupling device (1), particularly for universal joint transmissions, comprising: - a cylindrical casing (3), which is integral with a fork (30) of a universal joint, comprising a plurality of radial slots (32) provided on the inner circumferential surface (34) of the casing (3); - a pawl supporting cage (5), which is integral with a rotation shaft (50), comprising a plurality of radial seats (7), and is accommodated rotatably within said casing (3); - a plurality of pawls (9) adapted to be accommodated in the radial seats (7) of the cage (5); the pawls (9) are adapted to pass from a coupling configuration to an uncoupling configuration. The device further comprises an annular element (13), which can move axially between a retracted position and an advanced position, the annular element (13) comprising a plurality of tongues (130).