Overhead Crane Abnormal Noise: 5 Common Causes and Effective Repair Solutions 

Overhead crane abnormal noise is a common issue in bridge crane operations. This article analyzes the causes of abnormal noise in overhead crane operations, listing five potential factors: crane traveling mechanism, crane rails, crane runway girders, foundation settlement, and electrical systems. It also provides some solutions for the listed noise issues, hoping to be of assistance to you.

Analysis of Overhead Crane Abnormal Noise Causes

The abnormal noise described in this article refers to overhead cranes in their original state, where no components such as wheels, drive mechanisms, or motors have been replaced. Abnormal noise caused by the replacement of crane equipment is not within the scope of this article.

1. Causes of the Overhead Crane Traveling Mechanism

(1) Crane Wheel Causes

Overhead crane abnormal noise caused by crane wheels is common in practical applications, and the primary reasons include:

• Excessive horizontal or vertical misalignment of the wheels, leading to constant friction and collision between the wheels and rails during crane operation.
• Poor wheel bearing lubrication, which increases running resistance, and bearing damage, which causes sticking and abnormal noise.
• Excessive wear of the wheel flange and the crane runway rail.

(2) Guide Wheel Causes

The guide wheels of a crane are wheels with a vertical axis that help the crane or trolley stay on track in the correct direction. Improper installation or adjustment of the guide wheels can cause friction or collision between the guide wheels and the crane rails, leading to abnormal noise. As shown in Figure 1, the wear on the guide wheels can be quite severe.

(3) Drive Mechanism Causes

The crane’s drive mechanism discussed in this article uses the “three-in-one” drive mechanism as an example, though separately arranged systems can be referred to as well. The main causes of abnormal noise in the drive mechanism include:

• Abnormal noise from the “three-in-one” reducer, gear wear, or broken teeth.
• Two or more brakes not synchronized, damaged, or missing (as shown in Figure 2).
• Worn buffer pads (as shown in Figure 3).

(4) Crane Main Girder Causes

The main reasons for abnormal noise in the crane’s traveling mechanism caused by the crane main girder include:

• Excessive horizontal bending of the crane main girder, leading to diagonal misalignment.
• Significant changes in the camber of the main girder, causing variations in the wheelbase of the crane.

2. Crane Rail Causes

After prolonged crane operation, especially under full load, the stress on the rails increases, which can lead to abnormal noise during crane operation. If maintenance is insufficient, the issues can become more pronounced. The primary rail-related causes of abnormal noise include:

• Insufficient tightening or loosening of the rail clamp nuts (see Figure 4), causing deformation of the rail at the loose areas and resulting in abnormal noise during crane movement.
• Excessive gaps between the rail and the crane girder, missing or improperly placed shim plates.
• Vertical misalignment of the rail joints connected by fishplates exceeding the allowable tolerance, which has not been ground or adjusted, causing abnormal noise when the crane passes over it.
• Horizontal misalignment of the rail joints connected by fishplates, leading to abnormal noise; fishplate connections with excessive gaps (see Figure 5).
• Inadequate smoothness of welded rail joint seams, leading to cracks or joint detachment.
• Missing rail clamps, causing abnormal noise.
• Excessive deviation in the horizontal or vertical alignment of the rail along its length.
• Rail span exceeding the allowable deviation.
• Excessive height difference between the tops of two parallel rails.
• Incorrect or insufficient longitudinal offset of rail joint positions between the two parallel rails.
• Severe wear on the rail sides.

3. Crane Runway Girder Causes

• Excessive downward deflection of the steel runway girder, or lateral bending of the girder.
• Loose joints in the runway girder.
• Loose or missing bolts connecting the runway girder.
• Excessive height difference between adjacent girders (see Figure 6).
• Cracking or breakage of the concrete grout layer or leveling layer between the concrete crane girder and the rails.

4. Foundation Settlement Causes

Foundation settlement refers to the compression of soil layers under additional stress, leading to surface subsidence. Excessive settlement, especially uneven settlement, can cause buildings to tilt, crack, and become unusable. Foundation settlement is a general issue related to the entire factory structure. It can range from a few meters of small-scale local settlement to tens of meters of large-scale overall settlement.

Local settlement can cause parts of the runway girder to sink, resulting in gaps between the sunken girder and the crane rail (see Figure 7). This gap leads to abnormal noise during crane operation due to the increased stress on the rail. If not properly repaired and improved over time, it may cause permanent deformation or damage to the crane rail in the affected areas.

Overall settlement is a more severe form of foundation settlement, causing large-scale sinking of the runway girder. The unevenness of the settlement leads to height variations or horizontal deformation in the runway girder, which in turn causes corresponding vertical or horizontal deformation in the crane rails. During crane operation, the abnormal noise becomes more pronounced, making high-speed operation difficult or even impossible.

5. Electrical Causes

While most cases of overhead crane abnormal noise during crane operation are caused by mechanical issues, there are some electrical factors that can also contribute. These include loose or poor connections in the motor or brake wiring, as well as damage or wear to the brake pads.

Solutions for Overhead Crane Abnormal Noise

Each cause of abnormal noise in overhead crane operation is addressed with corresponding solutions.

1. Crane Traveling Mechanism Solutions

(1) Crane Wheel Solutions

• For issues with excessive horizontal or vertical misalignment of the crane wheels, the adjustment amount should first be measured. Refer to GB/T 14405-2011, and make adjustments based on the measured values. When adjusting horizontal misalignment, place shims in the vertical plane of the wheelset, and for vertical misalignment, place shims in the horizontal plane. After adjustment, perform a test run and check the gap between the crane wheels and the rail.
• For issues where poor wheel bearing lubrication increases running resistance, lubricating grease should be added promptly. Afterward, perform a test to check the flexibility of the bearings. If bearing damage causes sticking or abnormal noise, the bearings should be replaced immediately to prevent further issues.
• For excessive wear of the crane wheel flange and the rail, first investigate the cause of the wear, such as excessive wheel misalignment or improper rail installation. Normal wear on the wheel flange can be left untreated, but if the wear exceeds 40% of the flange’s design thickness, the wheel should be replaced.

(2) Guide Wheel Solutions

For abnormal noise caused by improper installation or adjustment of the guide wheels, adjust the gap between the guide wheel and the rail to ensure that there is either a gap during crane operation or minimal friction or collision. Check whether the positioning block is suitable, and if not, readjust it. Refer to GB/T 10183.1-2018 to check the axial parallelism tolerance of the horizontal guide wheels in both the direction perpendicular to and along the crane rails, as well as the height tolerance. Adjust any areas where the actual values exceed the tolerance.

(3) Drive Mechanism Solutions

• For abnormal noise from the “three-in-one” reducer, inspect the location where the noise occurs. If the gears are worn or have broken teeth, the gears should be replaced.
• For situations where two or more brakes are not synchronized, check whether the brakes are functioning properly. Use a feeler gauge to measure the brake gaps and ensure they meet the required specifications; if not, adjust the gaps accordingly.
• If the brakes or buffer pads are damaged, they should be replaced, and regular inspections should be performed.

(4) Crane Main Girder Solutions

Crane main girders typically do not deform easily. If deformation occurs, it is necessary to verify whether the design is appropriate, whether the manufacturing meets design requirements, whether the manufacturing process follows construction standards, and whether the crane installation is up to standard. For issues such as excessive horizontal bending of the main girder or significant changes in camber, repair methods like reinforcing the welds or using flame heating are generally used. Repairs usually require the involvement of the manufacturer or professional teams. The inspection of the main girder can be conducted in reference to GB/T 14405-2011.

2. Crane Rail Solutions

The handling of crane rails should focus on regular maintenance and upkeep to address issues at an early stage, preventing damage to the equipment.

• For issues with insufficiently tightened or loose rail clamp nuts, a combination of regular inspections and scheduled maintenance should be used to ensure the nuts are properly tightened.
• For excessive gaps between the rail and the runway girder, or if the length of the gap is too long, adjust the steel runway girder to bring the bottom of the rail closer to the top of the girder. If the gap exceeds 200 mm, use shim plates with a length of at least 100 mm and a width 10-20 mm wider than the rail base. No more than three shim plates should be used per set, and they should be securely welded to the steel girder. For concrete beams, use a similar method to that of the steel beams. Elastic shim plates are not recommended due to frequent wear over time.
• For excessive vertical or horizontal misalignment at fishplate rail joints, check for wear on the fishplates. If excessive wear is found, replace the fishplates. Then, adjust the rail joints and rails to ensure the vertical and horizontal misalignment does not exceed 1 mm, and the gap at the rail joints does not exceed 2 mm. In regions with temperature differences of 20°C or more, or during winter installations, consider a joint gap of 4-6 mm. Use a steel ruler and feeler gauge for measurement.
• For inadequate smoothness at welded rail joints, use a grinding wheel to smooth the top and sides of the joint to meet the required rail joint standards. For issues where welded rail joints crack or come loose, specialized welding personnel with specific materials and processes should handle the repair. Due to the complexity of crane rail systems, there is still a risk of cracking or loosening after welding. Therefore, fishplate connections are recommended over welding for bridge crane rail joints.
• For abnormal noise caused by missing rail clamps, check for missing components and secure them to ensure normal crane operation.
• For excessive horizontal or vertical curvature deviation along the length of the rail, adjust the rail so that the horizontal deviation over a 2-meter length does not exceed 1 mm, and the vertical deviation does not exceed 2 mm. The measurement can be performed using a steel wire method.
• For crane rail span deviations that exceed the allowable tolerance, adjust the rails to ensure that the maximum allowable span deviation ΔS is as follows:
  • When S≤16 m, △S =±5 mm
  • When S＞16 m, △S =±[5+0.25(S-16)]mm
  • ΔS: crane rail span deviation
  • S: the crane rail span
  • The maximum deviation must not exceed ±15 mm. For specific implementation, refer to GB/T 10183.1-2018, The crane rail span can be measured using a steel tape and spring scale.
• For excessive height differences between the tops of two parallel crane rails, adjust the runway girder and rail to ensure the height difference does not exceed 10 mm. Use a level to take multiple measurements.
• For parallel rail joints that are not longitudinally staggered or have incorrect stagger distances, adjust the rails to ensure the distance is no less than 600 mm and does not match the wheelbase of the crane’s front and rear wheels.
• If the wear on the rail sides exceeds 15% of the original rail width, the rails must be replaced.

3. Runway Girder Solutions

The quality of the runway girder is the foundation for ensuring the quality of rail installation. Before installing the rails, it is essential to ensure that the installation deviation of the runway girder meets the required standards. A detailed inspection of the runway girder must be carried out before rail installation, and the baseline of the runway girder should be marked during the inspection. This can be measured using a theodolite, while the level can be measured with a leveling instrument.

The acceptance of steel runway girders must follow the GB 50205-2017, while the acceptance of reinforced concrete runway girders must follow the GB 50204-2015. Currently, there is no specific standard for hybrid steel-concrete runway girders.

• For issues such as excessive downward deflection or lateral bending of the steel runway girder, it is necessary to verify whether the design meets the required standards and whether the installation is qualified. For repairs, heating methods may be used to correct the girder.
• For loose joints or loose and missing bolts in the runway girder, weld repairs and bolt tightening should be performed. If there is excessive height variation between adjacent girders, adjust the height of the neighboring runway girders to reduce the height deviation.
• If the concrete grout layer or leveling layer between the concrete crane girder and the rail is damaged, check the thickness of the secondary cast layer. If the thickness is insufficient, it is recommended to use other methods. If the thickness is adequate, new molds should be set up to pour cement, and after the cement has properly cured, the crane can resume operation.

4. Foundation Settlement Solutions

Early-stage foundation settlement is a relatively common occurrence. As foundation technology continues to advance, large-scale settlement problems have become less frequent, though localized settlement still happens occasionally. Localized settlement tends to occur on a small scale but still requires prevention and treatment.

(1) Prevention: Settlement can be monitored by setting up settlement monitoring points. Precision leveling methods are usually used to measure the amount of settlement.

(2) Treatment: For localized runway girder settlement caused by foundation settlement, professional repairs should be performed to eliminate the sinking and, in turn, resolve abnormal noise issues during crane operation. If the localized settlement is small, shim plates can be used between the runway girder and the rails, but the shim plates must be securely fixed to prevent them from becoming detached during crane operation.

5. Electrical Fault Solutions

For overhead crane abnormal noise caused by loose or faulty connections in the crane motor or brake wiring, the connection terminals should be tightened immediately, and regular inspections should be scheduled. If the brake pads are damaged, they should be replaced. If the brake pads are worn, first check the wiring to ensure it is functioning correctly, then observe the brake pads. If intermittent failure occurs, replace the brake pads, and if sufficient spare parts are available, proceed with replacement to prevent future issues.

Conclusion

Addressing overhead crane abnormal noise is crucial for ensuring smooth crane operations and preventing further mechanical issues. By understanding the common causes and implementing the appropriate solutions, operators can significantly reduce downtime and costly repairs.

Reference: Analysis and Solutions for Abnormal Noise in Overhead Crane Operations

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