The following systematic solutions can be taken to address the defects in the support points of electric hoists (electric single beam cranes), including defect analysis, handling measures, and prevention strategies:

1、 Types and causes of support point defects

Main beam deformation (deflection exceeding the standard)

Cause:

Manufacturing process: deviation in cutting dimensions, welding process defects (such as incomplete penetration and porosity).

Usage link: Overloading lifting, frequent braking impact, and high-temperature environment operation leading to material performance degradation.

Maintenance deficiency: Failure to regularly check the stress of the main beam and repair cracks in a timely manner.

Impact: Excessive deflection of the main beam will increase the running resistance of the trolley, causing climbing and sliding phenomena, and even leading to structural fracture.

The track installation is not standardized

Cause:

The method of fixing the track is not scientific (such as insufficient tightening force of the pressure plate bolts and inconsistent size of the hook shaped screws).

The track levelness/straightness exceeds the tolerance (such as uneven concrete beam pad iron, welding deformation).

Impact: Deviation or displacement of the track can exacerbate wheel wear, causing the phenomenon of "rail gnawing", and in severe cases, leading to derailment accidents.

Fatigue damage of supporting structure

Cause:

Long term exposure to alternating loads (such as frequent lifting and vibration).

The design strength of the support point is insufficient (such as the weld seam not being pre stretched).

Impact: Cracks or fractures in the supporting structure directly threaten lifting safety.

2、 Targeted solutions

1. Main beam deformation repair and reinforcement

Repair method:

Pre stressing method: Paste carbon fiber board or apply prestressed steel cable on the lower flange of the main beam, and counteract the deflection deformation by reverse tension.

Flame correction method: Linear heating is applied to the locally deformed area, utilizing the thermal expansion and contraction characteristics of the material to restore the geometric shape (requiring professional operation).

Reinforcement measures:

Add transverse reinforcement bars or longitudinal partitions to enhance the bending stiffness of the main beam.

Perform non-destructive testing (such as ultrasonic testing) on welds, repair cracks, and perform annealing treatment to eliminate stress concentration.

2. Quality optimization of track installation

Improvement of track fixation:

High strength pressure plate bolts are used to ensure that the fastening force meets the design requirements (such as M24 bolts with a torque of 300-350N · m).

Eliminate hook screws that do not meet the standards, use standard parts and install anti loosening devices (such as spring washers or double nuts).

Levelness/straightness adjustment:

Use a laser collimator or wire drawing method to detect track deviation, and control the deviation within ≤ 3mm/10m by adjusting the thickness of the shim (such as adding diagonal shim).

For concrete beam tracks, non shrink cement mortar is used to fill the gap between the pad iron and the beam body, ensuring a contact area of ≥ 60%.

3. Fatigue damage treatment of supporting structures

Crack repair:

For cracks in non load bearing areas, repair welding is carried out after grinding (the welding rod material matches the base material, and magnetic particle testing is performed after welding).

For cracks in the bearing area, it is necessary to replace the entire supporting component or partially cut it, and perform pre tensioning treatment.

Strength Enhancement:

Add reinforcing plates or angle steel near the support points to expand the bearing area.

Install rubber shock absorbers or spring dampers in high-frequency vibration areas to reduce the impact of alternating loads.

3、 Preventive maintenance strategy

Regular testing:

Every six months, use a total station to detect the deflection of the main beam and establish a deformation curve file.

Check the fastening status of the track pressure plate bolts every month and double check with a torque wrench.

Operating standards:

Overloading is strictly prohibited, and emergency stop and start should be avoided when lifting heavy objects.

After working in a high-temperature environment, it is necessary to cool down to room temperature before shutting down to prevent deformation caused by thermal stress.

Environmental management:

For corrosive environments (such as chemical workshops), regularly spray anti rust paint or use stainless steel material supports.

Keep the track area clean, promptly remove oil stains and debris, and prevent wheel slippage.

4、 Case reference

Repair of brake wheel wear on a certain gantry crane:

By changing the fixing method of brake shoes from rivet connection to pressure plate fixation, friction between rivets and brake wheels is eliminated, reducing wear by 80%.

Reinforcement of the main beam of an electric single beam crane:

After reinforcement with prestressed steel cables, the deflection of the main beam was restored from 15mm to 5mm, and the running resistance of the trolley was reduced by 40%.

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment