Summary of Loose Bridge Crane Trolley Rail Issues

During maintenance work, the issue of loose bridge crane trolley tracks frequently arises. Let's analyze the causes of this phenomenon from the following perspectives:

1. Uneven Wheel Alignment

1 The braking of the large wheels on both sides occurs sequentially.

     The sequence of braking causes a discrepancy in the stopping times of the wheels on both sides, leading to torsional oscillations of the bridge structure. In severe cases, this can even result in rail biting—a phenomenon where the wheels dig into the rails. As a result, the trolley wheels generate frictional forces along the main beam direction, perpendicular to the trolley tracks, which in turn loosens the trolley rails over time.

2 One side has braking, while the other has none—or the braking is barely noticeable.

      In this scenario, you’ll notice the bridge girder visibly twisting and swaying as the trolley starts or stops. On the side where braking is less effective, the end beams will swing back and forth, causing the trolley wheel flanges to come into contact with the sides of the rail. This generates horizontal lateral thrust, leading to increased friction between the wheel flanges and the rails—and ultimately resulting in rail loosening over time. Meanwhile, on the side where braking is more effective, the girder acts as a "support" during the twisting motion, creating friction along the rail gauge direction as well. If these issues aren’t addressed promptly, the rails will gradually become unstable and loose.

2. Uneven Cable Tray

      Uneven bridge girders can easily cause the four wheels of the trolley to lose alignment, leading to phenomena like "three-legged" operation during movement. As a result, the trolley may experience noticeable "bouncing," and in severe cases, it could even derail, generating friction forces along the wheelbase direction—ultimately causing the tracks and pressure plates to loosen.

3. The Wheel Issue

 1 1. Wheel horizontal deviation occurs due to deformation of the bridge girder, which causes the end beams to bend horizontally, resulting in either excessive wheel alignment deviation or already existing excessive deviation during wheel installation.

 2 1. Wheel vertical deflection occurs due to deformation of the bridge girder, resulting in excessive vertical deviation of the wheels. During installation, ensure that wheels within the same set are slightly tilted outward, which helps minimize wheel vertical deflection once the bridge girder is under load.

 3 • The diameters of the two drive wheels are unequal. As the crane operates, the speeds on the left and right sides differ.

 4 The front and rear wheels are not running in the same straight line. Excessive deviations in span or diagonal measurements, caused by deformation of the bridge structure, prevent the front and rear wheels from aligning properly on a single line.