Unit for bead breaking in tyre changing machines

The unit (1) for beading tyres in tyre changing machines or the like comprises a bearing structure (2) associable with a tyre changing machine (A) or the like, a supporting element (3) associated with the bearing structure (2) and moving with respect to the rim (C) of a wheel (D) mounted on the tyre changing machine (A), first actuator means (6, 8) for moving the supporting element (3) on the bearing structure (2), a beading tool (4) associated with a free extremity of the supporting element (3), and second actuator means (12) and transformation means (13) for transforming the movement generated by the second actuator means (12) in the translation movement of the beading tool (4) along a substantially curvilinear trajectory between a first extreme position, in which the beading tool (4) is substantially retracted with respect to the rim (C), and a second extreme position, in which the beading tool (4) is substantially closer with respect to the rim (C).