Electric overhead travelling (eot) crane mainly includes three major operating mechanisms: a lifting operating mechanism, a trolley operating mechanism, and a trolley operating mechanism. The hoisting mechanism is mainly composed of electric hoist, wire rope, pulley, hook or spreader. The metal structure of the electric single-girder bridge crane is mainly composed of a main beam and an end beam. The main beam structure is mostly a combined section of I-beam and steel plate, which is composed of a cover plate, a web and an I-beam, and there are longitudinal and short reinforcing ribs in the box. Its safety and reliability directly affect the operating quality and working ability of the crane.