Patent ID: 8376018

Claim:
A tyre-changing machine comprising a chuck ( 5 ) having a self-centring group ( 51 ) for blocking a rim ( 100 ) of a wheel, which self-centring group ( 51 ) comprises a plurality of blocking jaws ( 7 ) of the rim ( 100 ) arranged angularly equidistanced along a circumference centred on a rotation axis (A) of the chuck ( 5 ), and means for moving ( 52 , 57 ) for radially distancing and nearing the blocking jaws ( 7 ) with respect to the rotation axis (A) of the chuck ( 5 ) such as to vary a diameter of the circumference on which the blocking jaws ( 7 ) are arranged while maintaining an inclination of each blocking jaw ( 7 ) constant with respect to the rotation axis (A) of the chuck ( 5 ), wherein each blocking jaw ( 7 ) comprises a first portion ( 70 ) which is connected to the means for moving ( 52 , 57 ), and a second portion ( 71 ) which is movably coupled to the first portion ( 70 ) such as to be able to change an overall development of the blocking jaw ( 7 ) in a radial direction with respect to the rotation axis (A) of the chuck ( 5 ), and wherein the second portion ( 71 ) is coupled to the first portion ( 70 ) by means of a joint ( 72 ) for defining a reciprocal rotation axis (B).