Gantry cranes represent the constructions with the horizontal bridge based on two pillars, moving on land rail tracks. Both bearings have a tight junction with the bridge, while one of the pillars of the bridge can be held by hinges.
Those cranes whose superstructure rests on one side of the support leg and the other one mounted directly on the truck running, are called semi-cranes. Rail tracks in this case are located at different levels, one on land and the other one on a special trestle or columns of the building.
There are two basic schemes used for bridge design – beam and girder. Single-girder bridges with triangular and quadrangular cross section with sled monorail are the most widespread. This construction has proved its cost-efficiency, and the large industry players, like Granada Material Handling, focusing on gantry hoist and overhead crane manufacturing, concentrate plenty of their effort on single-girder bridges.
The span girder and double-girder bridges in their design are usually similar to the beam overhead cranes. Rigid and flexible support of gantry cranes is carried out through individual racks which design depends on the type of support. Flexible support pillar has a single element or a farm, rotate in a direction perpendicular to the bridge.
Spatial rack of rigid supports have a trihedral or tetrahedral design, and belts for their ruggedness are associated with diaphragms or bars. Racks of support mate with spans on the flange is connected tions or hinges. Applications must be last on the crane, installation of which is produced by the contraction of racks. Pivot axis in this case is parallel to the longitudinal axis of the bridge. At the bottom of the rack supportive communicate ties, studs or to the undercarriage or the lower parts of the struts.
Gantry cranes can be manufactured with one or two consoles or without them. The length of the console is selected in accordance with the purpose of the crane. Gantry cranes, general purpose, as well as bridge cranes of general purpose, feature a mechanism to lift the load, and ensure the trolley and crane movement. The drive mechanisms and lifting the trolley can be mounted directly on the trolley (motorised vehicles) or stationary on the bridge (truck cable steering). As a trolley in the capacity of the crane up to 5 ton and average mode commonly used standard electric hoists (hoists), moving in riding the monorail beam. The heavy-duty cranes utilise monorail cable and motorised vehicles or double rail. Last executed as suspension and support. Support carts move on rails laid on the upper zone of the bridge beams. The gantry cranes with support trucks typically utilise standard trolleys and overhead cranes.
The mechanisms of movement of gantry cranes of general purpose are carried out with separate drive supports. Structurally, these mechanisms are performed in a rack fastened to the base with the supports bolted flanges one or two-wheeled carts. For small spans of the cranes are equipped with fixed control cabin being located on a rigid support. At larger spans, when monitoring the lifting body from one place is difficult, cockpit perform moving together with the trolley.