Non-return block for snow chains having inserts to protect wheel

A non-return block (5) for locking a terminal tensioning portion (7) of snow chains (2), comprising a body (51) which defines a channel (12) within which the terminal portion (7) passes and a ratchet or pawl (13) pivoted to the body (51) to lock said terminal portion (7), characterised in that it comprises at least one insert (62, 63) of soft material on at least one side surface of the body (51) of the non-return block so as to protrude laterally therefrom to come into contact with the rim (8) of the wheel of the vehicle preventing deterioration thereof through rubbing, the insert of soft material (162, 163) being fixed to said body (51) of the non-return block by coupling with screw means (167), wherein the body (51) of said non-return block has a through hole (154) that puts two drawn seats (55) into communication and in that each of said inserts (162) comprises a through hole (165) communicating with a recessed seat (166), in which screw means pass through the holes (165) in the inserts (162), and the hole (154) for communication of the two drawn seats (55) being able to receive the shank of said screw means (167), and the recessed seats (166) of said inserts (162) being able to receive the head of the screw means and respective nuts (168) for locking of the screw means.