The article is kindly prepared by Granada Material Handling, a leading manufacturer of gantry hoist and overhead crane equipment with facilities across the United Kingdom. The post focuses on metal elements of bridge cranes and depicts the mechanisms of their functioning as well as their purpose and functions.
A metal construction of bridge crane consists of the bearing parts, assembly units and components not related to the support structures. The core elements set is comprised of: longitudinal and transverse beams and the bridge as a whole, working platforms that accommodate the trolley, carriages, farm, rails, running wheels, runway, fasteners off-design elements. The load-bearing process doesn’t involve structures and elements for self-supporting areas, decks, stairs, railings, fences, siding booths and other elements.
Steel used for load-bearing steel elements, should have the same structure and chemical composition uniformity over the entire length of hire, offering the required mechanical strength and stability. The requirements for steel take into account the specific conditions of operation of an overhead crane, which is of particularly important in the context of their work at low temperatures.
Metalwork bridge crane with a main box girder has a main beam, formed by two vertical walls and two horizontal flanges, called zones. The upper zone of the main beams accommodates the rails. The vertical gravity load from the trolley and the load is transferred to the vertical walls and equally as rails laid symmetrically relative to the vertical axis of the main beam. Horizontal load at start-up and braking of the crane are directed to the upper and lower zones. The rigidity of the main beams is provided by large and small diaphragms. For the trolley current supply, installation of movement mechanism and electrical cabinet, the outer vertical walls of the main beams carry buckled or stamped brackets trolley and working platforms which are covered with flooring made of corrugated sheet and have a railing. The platform of the bridge is designed for central drive of the mechanism of movement is also a transition area. The crane with a separate drive work platforms is located only near the end beams.
If the main girder bridges have box-sections, the end of the beam must also be a box section. To ensure the rigidity of the connection with the main beams aperture is also set in end beams. A main beam with a terminal is connected by welding, bolts and rivets.
Truss bridge crane metal structure consists of a main farm, which is laid across the upper belt rail takes the load from the force of gravity with a cargo truck, and auxiliary farm positioned in parallel to it. The main and auxiliary farm is linked to the upper and lower horizontal trusses, perceiving horizontal loads acting on the bridge at start-up or braking of the crane. To ensure the stiffness of the bridge a transverse diaphragm is used, which is installed in the plane of the main and auxiliary struts farms. The upper and lower belts of the farm are made from T-section main profile, and the upper and lower bars farms – from the angle of the profile.