What factors influence the operational efficiency of double-girder cranes?

In bridge construction projects, road and bridge cranes are a common industrial equipment used for lifting and hoisting operations. The efficiency of this equipment directly determines the progress of the entire project. What aspects impact the system's operational efficiency?

The crane's startup speed significantly impacts overall operational efficiency. Equally important are stability and smooth performance characteristics. A combination of rapid startup speed and stable operation can substantially enhance efficiency.

While the startup speed of gantry cranes influences efficiency, it cannot be increased indefinitely. Increasing speed must be balanced with maintaining equipment stability. Excessively high speeds can amplify vibration and sway during operation.

Such occurrences not only fail to boost efficiency but also pose severe risks to operational safety. Therefore, the adopted speed must remain within scientifically reasonable limits to achieve optimal results and complete tasks promptly.

What causes the load-bearing beam of a double-girder crane to sag?

1. The metal components of a double-girder crane experience stresses of varying directions and magnitudes at different locations. Some of these stresses originate from load application, while others result from manufacturing processes such as welding seams and uneven contraction of surrounding metal. During crane operation, these stresses tend to equalize or dissipate, leading to structural plastic deformation.

2. Impacts from transportation, storage, and lifting operations. Improper transportation, storage, hoisting, and installation can all cause deformation of the crane structure.

3. Application-related hazards: Double-girder cranes are customized for specific operating conditions. Overloading, excessive wheel loads, and other improper applications can also cause cable tray deformation. For instance, a 75-ton double-girder jib crane in a factory experienced a 40mm downward displacement of its load-bearing beam within three years due to frequent high-intensity operation.

4. Maintenance Method Impacts: Oxy-fuel cutting or welding on the bridge without deformation prevention measures, or uneven heating, will cause cable tray deformation. Rigid cranes feature both ground and aerial operation modes. Ground operation includes wired handle control and controller handle control; aerial operation refers to cab operation. Cockpits come in open or enclosed configurations, installable on either left or right sides based on site conditions. Entry points include side or end access to accommodate diverse customer requirements.

5. Effects of High Temperatures

Double-girder flat-arm cranes in heat treatment workshops exhibit more frequent and severe girder deflection than those in cold-drawing workshops. The primary cause is that heat radiation from the smelting process causes the temperature of the lower cover plate of the load-bearing beam to exceed that of the upper cover plate. This results in a higher expansion rate for the lower plate than the upper plate. Under load, this leads to a natural reduction in the beam's deflection.