The gantry crane is a bridge type crane whose bridge is supported on the ground track through the support legs at both ends. It is mainly composed of gantry (main beam, end beam, outrigger, lower beam, trolley running track and cab installation), lifting trolley, crane running device and electrical control system. The crane trolley is equipped with a lifting mechanism and a trolley running mechanism, which runs horizontally along the trolley track on the main girder of the bridge; the main beam can extend the outrigger to one side or both sides to form a cantilever, but the cantilever length is generally less than or equal to 1 / 3 span, so as to increase the service range of the crane. The crane runs longitudinally along the foundation track of the open place to form a rectangular working site.
Gantry crane is widely used in machinery processing, metallurgy, chemical industry, nuclear power station, shipbuilding, port and wharf, etc.
According to the different pick-up devices, they can be used in different workplaces or specific work processes, including hook gantry crane, grab bucket gantry crane, electromagnetic gantry crane and electromagnetic hanging beam gantry crane.
Hook gantry crane is widely used in mechanical processing, warehouse, freight yard and other places with hook as retrieval device; grab bucket gantry crane is widely used for loading and unloading bulk goods in warehouse, stockyard and open-air freight yard; electromagnetic gantry crane is widely used with detachable electromagnetic sucker as picking device Assembly and handling of magnetic conductive black products and materials, such as ingot, section steel, pig iron block, scrap iron and scrap steel, etc. in the fixed span indoor or outdoor for metallurgical and mechanical processing.
In the crane, the mechanism used to lift or lower the goods is called the lifting mechanism, which generally adopts the winch type. The hoisting mechanism is the most important and basic mechanism in crane, and its working quality directly affects the working performance of the whole crane.
The hoisting mechanism is generally composed of driving device, wire rope winding system, picking device and safety protection device. The driving device consists of motor, reducer, brake, drum group and coupling. The wire rope winding system consists of wire rope, drum block, pulley block and hook group. There are many kinds of fetching devices, such as hook, ring, grab, electromagnetic sucker, spreader and hanging beam. Safety protection devices include overload limiter, lifting height limiter, overspeed protection switch and safety brake.
The working principle of the lifting mechanism: the motor rotates after being electrified, changes speed through the reducer, drives the drum through the coupling, and completes the lifting and lowering process of the hook through the wire rope winding system.
The hoisting mechanism adopts series resistance speed regulating system, which has stable starting and braking, small impact and accurate hook positioning, which not only improves the production efficiency, but also greatly extends the service life of various parts of the lifting mechanism.
The scheme of supporting braking and control braking is adopted for the braking of hoisting mechanism. Electric braking is adopted for control braking, while brake is set on the high-speed shaft of motor for braking, so as to make the braking of lifting mechanism stable, safe and reliable.
The components of the hoisting mechanism are arranged compactly, easy to maintain, and safe and reliable.
Trolley Running Mechanism
The running mechanism is the power device to drive the crane trolley. In order to improve the working efficiency of the crane, the speed is generally relatively fast. In order to ensure the synchronization of the driving wheel of the crane trolley and avoid the equipment failure and safety accident caused by the trolley gnawing the rail, the trolley running mechanism often adopts the low-speed shaft centralized drive.
The motor drives the wheel through the vertical reducer, coupling and transmission shaft fixed on the trolley frame. The driving wheel usually takes half of the total number of wheels, and the brake is placed on the extension shaft at the other end of the motor or integrated with the high-speed shaft coupling. This form has the advantages of compact structure, good interchangeability of parts and convenient installation and maintenance.
Portal Frame of Gantry Crane
The portal frame is the main stress component of the crane, which adopts the structure of double beam and double rail. The main stress components are main beam, end beam, outrigger and lower beam, supplemented by trolley rail, walking platform, railing, ladder and other auxiliary metal structures.
Crane Running Device
The crane is supported by four corner wheels or wheel groups. Two or more independent driving systems are used to drive the crane separately.
The transmission type of the crane driving system is: a motor drives a reducer through gear coupling and transmission shaft, and the low-speed shaft of the reducer is connected with the wheel shaft by the coupling, and the driving wheel ratio is 1:2. When starting, the driving wheel does not slip, and when braking, it is stable and reliable. This kind of structural arrangement is beneficial to the installation, maintenance and disassembly of various parts of the drive system.
The wheel diameter and material selection of the crane running mechanism is based on the maximum supporting force of the wheel under the most unfavorable working conditions, so as to ensure that some wheels will not be overloaded.