Gantry crane is a kind of overhead bridge crane in which the bridge frame is supported on the ground track through the legs at both ends. It is mainly composed of gantry frame (main beam, end beam, leg, lower cross beam, trolley running track and cab), hoist trolley, crane running mechanism, and electrical control system.
Gantry Steel Structure
The gantry metal structure is the main force-bearing component of the crane. The main beam, end beam, leg and lower crossbeam are the main force-bearing components, supplemented by trolley tracks, walking platforms, railings, ladders and other auxiliary metal structures.
- Main beam
The material of the main beam is Q235-B, and the minimum plate thickness is not less than 6mm.
The main beam can extend out of the legs to one or both sides to form a cantilever, thus increasing the operation range of the crane. The length of the cantilever is generally less than or equal to 1/3 of the span length.
- End beam
The end beam is a box-shaped structure, and the connection between the end beam and the main beam is a rigid connection.
In order to facilitate transportation, the main beam and end beam are connected by high-strength bolts, and each connecting plate is positioned by reamed bolts.
- Support leg
The leg adopts a trapezoidal cross-section structure with a large upper and a small lower section.
The upper flange of the leg and the main beam flange support are connected by high-strength bolts, and the lower flange of the leg and the upper connecting flange of the lower cross beam are connected by high-strength bolts.
- Lower cross beam
The lower cross beam is a structural member that carries the weight of the crane and the load.
The lower crossbeam is a box-shaped composite beam formed by welding and splicing steel plates, which has a stable structure and strong bearing capacity.
- Trolley track
The trolley track adopts the whole track with joints welded together to ensure that the trolley runs well.
- Walkway and railing
The tread of the bridge platform is made of non-slip patterned steel plate with a thickness of 3mm. Railings with a height of 1050mm are installed on the passages of the bridge.
The design of the cabin takes various functional requirements, sturdiness, durability, safety and reliability into consideration. It also ensures that the operator has a wide view.
An alarm is also set up in the driver’s cabin to ensure the safe operation of the crane.
Gantry Crane Hoist Trolley
The hoist trolley is equipped with a lifting mechanism and a trolley running mechanism that runs laterally along the trolley track on the main girder of the crane.
The lifting mechanism is used to lift and lower the load, which is the most important and basic mechanism in the crane.
Components of the lifting mechanism: driving device, steel wire rope winding system, lifting device and safety protection device.
Driving device – motor, reducer, brake, drum set and coupling.
Steel wire rope winding system – steel wire rope, drum group, pulley group and hook group.
Lifting device – it can be hooks, grabs, electromagnetic chucks, hanging beams, spreaders, etc.
Safety protection device – overload limiter, lifting height limiter, overspeed protection switch and safety brake.
Features of the lifting mechanism: the hoisting mechanism adopts a series resistance speed control system with stable braking, small impact and accurate hook positioning, which not only improves the production efficiency, but also greatly extends the service life of the parts of the hoisting mechanism.
Working principle of the lifting mechanism: the electric motor rotates after being energized, through the reducer to change speed, and then drives the drum through the coupling, and finally completes the lifting and lowering operation of the hook through the wire rope winding system.
The trolley running mechanism is the power device that drives the hoist trolley. In order to improve the working efficiency, the speed of the running mechanism is generally faster.
In order to ensure the synchronization of the driving wheels of the hoist trolley and avoid equipment failure, the trolley running mechanism often adopts concentrated drive with low-speed shaft.
Crane Running Mechanism
The crane running mechanism uses two or more independent drive systems to drive the crane separately.
The diameter and material of the gantry crane wheels are selected according to the maximum supporting force of the wheels under the most unfavorable conditions to ensure that some wheels will not be overloaded.
Electrical Control System
- Power supply
The standard power supply of our gantry cranes is three-phase AC, the rated voltage is 380V, and the rated frequency is 50Hz. It can also be designed according to user requirements.
- Power supply mode
Trolley feed: cable trolley. The slides used for the feed of flexible cables and cable trolleys can be steel rope slides, I-steel slides, and special-shaped steel slides.
Crane feed: safety slide wire, cable reel.
- Electrical protection system
Loss of voltage protection
Emergency power-off switch
Travel limit switch
Zero position and interlock protection
Phase failure, overvoltage, and undervoltage protection
- Operation methods
Wireless remote control
To learn more about gantry crane structure and components, please feel free to contact us!