Patent ID: 7467831

Claim:
A track-tightening device for crawlers, comprising an undercarriage or bogie consisting of a structure ( 20 ) which includes elements ( 21 ) for carrying a plurality of fixed lower supporting rollers ( 2 ), as well as idler back-pull wheels ( 11 ) and optionally a crawler wheel, said structure ( 20 ) also housing a guide system ( 25 ) for controlled axial sliding of the track-tightening device ( 5 ) carried by a second movable structure ( 8 ), said second movable structure ( 8 ) being equipped with fittings ( 26 ) which interconnect with the guide system ( 25 ), said second movable structure ( 8 ) having an idler wheel ( 3 ) as well as at least one movable supporting roller ( 22 ) capable of following the longitudinal movement of the idler wheel ( 3 ), the structure ( 20 ) and the second movable structure interact by way of a guide ( 25 ) and fittings ( 26 ) to modify the wheel base between the idler wheel ( 3 ) and the back pull wheel ( 11 ) of the bogie by axial sliding, wherein the structure ( 20 ) is box shaped and where at least one of said movable lower supporting rollers ( 22 ) is in constant contact with the idler wheel ( 3 ) so that their reciprocal distance does not vary during the operating life of the vehicle, under any operating condition and with any range of the track-tightening device, said movable lower supporting roller ( 22 ) being attached to said second movable structure ( 8 ) so that the length of a section of track situated between the axis of the idler wheel ( 3 ) and the axis of said movable lower supporting roller ( 22 ), is constant and at a minimum value during the functioning of the crawler under all conditions.