Emergency handling of the rotary jumping fault of DMQ540/30BI Elevated Gantry Crane

When a DMQ540/30BI overhead gantry crane of our company was installed and put into operation, the machine made abnormal noises while rotating and the whole machine vibrated greatly. After investigation, it was found that the cause of the fault was that the rotary table was out of round (the rotary table was not measured during ground assembly), and the radius between the rotary table and the A and B corners of the rotating platform was too small. The on-site measured data was -12mm. The traditional approach is as follows: Use a 50-ton crane to remove the chassis of the entire machine, lift it out, and place the turntable and the rotary platform on the ground together. First, find a radius of 3500mm from the center point to the processing center point of the pinion pin, correct the radius of the rotary platform circle within the range of 3500mm, ensure the roundness, and then tighten the fixing screws. Where the force is greater, an iron plate with δ=12 or δ=16 can be added to the inner side for positioning and fixation. Such a construction period usually takes about 7 days and costs around 80,000 yuan. Considering the construction period and economic benefits, we adopted the method of on-site processing: First, the outer positioning iron plates at corners A and B were cut off by air cutting. Then, the cycloidal gear and pin gear pin were used to rotate to this position. The rotary platform could push the rotary table outward by about 8mm. At this time, on the inner side of the rotary table, A δ=12 or δ=16 iron plate is welded to each end of the upper plane of the central suspension connection plate to support the rotary disc, preventing it from moving inward. This ensures that the contact between the cycloidal gear and the pinion pin reaches above 0, and at this point, the test run fault is eliminated. The author reminds all colleagues that in the future, when installing machines, all components must be thoroughly inspected on the ground before installation to avoid both time-consuming and uneconomical operations.