Main supporting leg mechanism of bridge girder erection machine

The invention disclose a main supporting leg mechanism of a bridge erecting machine. The mechanism comprises a main supporting leg transverse main beam, two heightening frames are fixed to the bottomface of the main supporting leg transverse main beam, the bottom faces of the heightening frames are fixed to the top face of the middle of an upper telescopic outer sleeve part, and a lower telescopic outer sleeve part is arranged under the upper telescopic outer sleeve part. Two main vertical supporting legs are inserted into the upper telescopic outer sleeve part and the lower telescopic outersleeve part in a sleeved mode, a supporting leg lifting oil cylinder is arranged in the middle between the middle of the upper telescopic outer sleeve part and the lower telescopic outer sleeve part,and a top oil cylinder base of the supporting leg lifting oil cylinder is hinged into the upper telescopic outer sleeve part through a hinge shaft. The end part of a push rod of the supporting leg lifting oil cylinder is hinged