The hoisting mechanism of gantry crane, trolley operation mechanism and bridge frame are basically the same as the bridge crane.
Because of the large span, the crane operation mechanism mostly adopts the separate driving method to prevent the crane from causing the skew operation to increase the resistance and even the accident.
Gantry crane trolley is operated on the bridge, and some of the lifting trolley is a jib crane.
The legs on both sides of the bridge are usually rigid legs;
Spans more than 30 meters, is often a side for rigid leg, but on the other side through the ball joint and the bridge connecting the flexible leg, make the door frame statically determinate system, so that you can avoid outer load under the action of the additional stress due to the lateral thrust, also can compensate bridge longitudinal temperature deformation of the gantry crane windage area is large, in order to prevent the slide under the action of strong wind overturned or, with a sonde and interlock with running institutions of crane rail device.
The bridge can be without cantilever at both ends;
It can also be a cantilever at one end and a cantilever at both ends to expand the scope of work.
The half-gantry crane bridge has a leg at one end and no legs on the other, which runs directly on the high platform.