Supporting leg structure of road bridge girder erection machine

The utility model relates to the technical field of bridge girder erection machines, in particular to a road bridge girder erection machine supporting leg structure which comprises a top plate and an expansion supporting plate, the two sides of the bottom end of the top plate are each provided with a first hydraulic push rod, the outer side of a supporting column is sleeved with a sliding plate, and the bottom end of the sliding plate is provided with a first hinge key; a supporting connecting rod is hinged to the interior of the first hinge key, a second hinge key is installed at the top end of the extension supporting plate, and the bottom end of the supporting connecting rod is hinged to the second hinge key. The sliding plate can slide back and forth on the outer side of the supporting column through the extension of the output end of the first hydraulic push rod, and when the sliding plate moves downwards through the extension of the output end of the first hydraulic push rod; the four expansion supporti