I. The core components of a bridge crane
1. Metal structure
The metal structure is the skeleton of the crane, including the main beam, end beam and walkway. The main beam is usually designed in a box or truss type, with a span range of 10~35 meters (according to GB/T 14405-2011 standard) and a load capacity of 5~500 tons. The end beam connects the main beam and supports the running mechanism, while the walkway is used to install electrical equipment and maintenance channels.
2. Lifting mechanism
Responsible for vertical lifting of goods, it consists of an electric motor, brake, reducer, drum and wire rope. For example, a crane with a rated lifting capacity of 20 tons usually has a wire rope diameter of 18~22 mm (refer to ISO 4308 standard), and uses a dual-speed motor for precise control.
3. Running mechanism
It is divided into trolley operation (lateral movement) and trolley operation (longitudinal movement). The trolley running mechanism drives the entire crane along the track, while the trolley running mechanism drives the lifting mechanism to move on the main beam. Modern cranes mostly use variable frequency speed regulation technology, and the operating speed can reach 20~60 meters/minute.
4. Electrical system
Including control cabinet, operating device (such as remote control or cab), sensor and power supply slide wire. Key components must comply with IEC 60204-32 safety standards, with a protection level of IP54 or above to ensure dust and water resistance.
5. Safety devices
Essential devices include overload limiter, limit switch, buffer and sound and light alarm. For example, the error of overload limiter must be controlled within ±3% (according to GB 6067.1-2010) to prevent overload accidents.
2. Extended knowledge: Selection and maintenance points
1. Selection recommendations
- Select the model according to the span of the plant, lifting weight and working level (such as A5 for medium frequency of use).
- H-class insulation motors should be used in high temperature environments, and stainless steel structures are recommended for corrosive environments.
2. Maintenance focus
- Check the wire rope for wear every month (if the number of broken wires exceeds 10%, it must be replaced).
- Lubricate the operating mechanism bearings regularly and perform a load test once a year.
From the above analysis, it can be seen that the design of the bridge crane takes into account both functionality and safety. Reasonable selection and standardized maintenance can significantly extend the life of the equipment.
