Patent ID: 7614465

Claim:
A working machine having a main frame structure which includes a pair of endless tracks with each track entrained about track supporting devices mounted by a track sub-frame, the sub-frame including inner and outer members interconnected by cross members with the inner and outer members arranged side by side, at least one upper track support device mounted between the inner and outer members at or adjacent upper edges thereof, at least one lower track supporting device mounted between the inner and outer members at or adjacent lower edges thereof, and wherein the inner and outer members and cross members of at least one of the track sub-frames being provided by a monolithic casting, and wherein at least one of the inner and outer track sub-frame members provides a mounting for a track tensioning mechanism for maintaining a desired tension in the track entrained about the track supporting devices the main frame structure including a main frame part which lies between the pair of track sub-frames, the main frame part including a central portion for supporting a part of a slewing mechanism, the machine including an upper frame structure which is rotatable about a generally upright axis relative to the main frame structure, by the slewing mechanism, the central portion of the main frame part being attached to the inner member of each of the track sub-frames by connecting arms, which are provided by elements fabricated in a material which is weldable to the track sub-frames and wherein the inner of the track sub-frame members of the track sub-frame monolithic casting includes for each connecting arm, one or more integral formations which extend inwardly of the machine towards the central portion, the connecting arms being welded to the integral formations.