【Feima Crane】 Maintenance and upkeep of the gourd bridge type universal overhead crane

The correct use and maintenance of cranes are closely related to safety production and the service life of cranes. Therefore, it is necessary to regularly inspect and test cranes. The inspection or testing must comply with the requirements of GB6067-85 "Safety Regulations for Cranes" and other relevant documents.

【Maintenance and upkeep of mechanical equipment】

1. Lubrication: The quality and lifespan of the various mechanisms of a crane largely depend on regular and correct lubrication. Generally, the lubrication condition of each lubrication part should be checked every three months, and oil should be added or replaced.

The various mechanisms of this series of cranes adopt a dispersed lubrication method, so it is necessary to check the unobstructed oil cup at all times. The use of lubricating oil (grease) is related to the working characteristics and temperature of the mechanism. In places with high temperatures, oils or greases with higher viscosity can be selected.

The bearings in the large and small wheels can be lubricated with a mixture of No. 3 calcium based grease and heated oil, with a ratio of 4:1.

The gear of the reducer adopts oil pool splash lubrication. Gear oil (SYB1103-625) is used in winter and HL-20 is used in summer. The amount of lubricating oil injected into the box is measured with an oil needle, and the oil level should reach between the upper and lower markings of the oil needle.

The steel wire rope must be lubricated on time and correctly. The old oil should be cleaned with a cloth soaked in kerosene. It is absolutely forbidden to use metal brushes or other sharp tools to clean the dirt on the steel wire rope; The use of acidic or other highly corrosive lubricants is also absolutely prohibited.

2. Lifting equipment group: Lifting equipment is one of the important components in cranes and must be inspected regularly. If any of the following situations are found, the hook or its attached parts should be immediately scrapped and replaced with new hooks or parts (the hook is strictly prohibited from being welded before use).

• Any cracks appear on the surface.
• Plastic deformation occurs at the dangerous section or hook neck.
• Hook torsion deformation exceeds 10 °
• The wear of the dangerous section of the hook has reached 10% of the original section height.
• The opening degree of the hook has increased by 15% compared to the original size
• Fatigue cracks appear near the retraction groove or transition fillet of the hook tail.
• Any cracks or deformations in nuts, hooks, and crossbeams

3.When any of the following situations occur in the pulley system, it should be scrapped.

• crackle.
• The uneven wear of the wheel groove reaches 3mm.
• The wear of the pulley wall thickness reaches 20% of the original wall thickness.
• Due to wear and tear, the diameter of the bottom of the wheel groove has decreased by 50% of the diameter of the steel wire rope.
• Other defects that damage the steel wire rope.

4. Reducer: Regularly check the lubrication of the gears, the meshing of the gear pairs, and the temperature of the bearings. If any abnormal conditions are found, immediately stop the vehicle for maintenance.

(1) During the initial use of the reducer (within six months), the lubricating oil should be replaced every three months. Afterwards, based on the decomposition, oxidation, and cleanliness of the oil, the lubricating oil should be replaced every six months. When changing the oil, kerosene should be used to flush the inner wall of the gearbox.

(2) The gearbox should be thoroughly inspected every six months by opening the box cover to check for defects such as pitting, scratches, bonding, and cracks in the gears; Check whether the bearings and sealing parts are worn, and replace or repair them according to different requirements.

(3) When the reducer leaves the factory, it is sealed with a static surface. When opening the box for inspection and maintenance, the residual sealant on the joint surface should be removed, and new liquid sealant should be evenly applied. After the sealant has slightly polymerized, the box should be closed and the bolts tightened.

(4) The rapid forward and reverse movement greatly reduces the service life of the reducer and affects its safe use. The above situation should be avoided.

5. Wheel assembly should be regularly inspected, and if any of the following situations occur, it should be scrapped:

• crackle.
• The wear of the wheel rim thickness has reached 50% of the original thickness
• The bending deformation of the wheel rim thickness reaches 20% of the original thickness
• The wear and tear on the tread surface has reached 15% of the original thickness
• When the operating speed is below 50m/min, the ellipticity reaches 1mm, and when the operating speed is above 50m/min, the ellipticity reaches 0.5mm.
• The deviation between the working diameters of two active wheels caused by uneven wear shall not exceed 1/600 of their nominal diameter. If this value is exceeded, the vehicle should be re polished, and the wheels after heavy loading should meet the requirements of Article 4.

​​​​​​​【Maintenance and upkeep of metal structures】

• The bridge frame is the most important load-bearing component in the metal structure of a crane, and the quality of maintenance work directly affects the safety and performance of the crane. Therefore. Attention should be paid when using:
• It is necessary to avoid sudden starting, braking, and collision with another crane, as such sudden movements can cause significant additional impact dynamic loads on the bridge.
• Regularly measure the deflection of the main beam to verify whether it has exceeded the specified deformation.
• Inspect the main beam, end beam welds, and other major welds. If cracks are found in the welds, they should be immediately stopped from use, and then the cracked welds should be removed and re welded with high-quality welding rods (E4303). Attention should be paid to the process during re welding to ensure welding quality and prevent welding deformation. And check whether the connecting bolts between the main beam and the end beam are loose.
• When residual deformation (or web instability) is found in the main beam. It should be stopped immediately and a customized repair method should be developed after research.
• After the repair or reinforcement of the bridge frame, a test run should be carried out using the same method as described above. Only after passing the test can it be applied.
• For the track, the main observation is whether it is straight, whether the pressure plate is firm, and whether there is any looseness. If it is found that the track is stuck when the car is walking, efforts should be made to correct the track or adjust the wheels.

【​​​​​​​Maintenance and upkeep of electrical equipment】

In order to ensure the reliable and safe operation of the crane, it is necessary to establish an electrical equipment maintenance system that complies with GB6067-85 regulations, and be familiar with the causes of various equipment failures and methods to eliminate them. The maintenance of the main electrical equipment is now described below:

• To extend the service life of electrical equipment in cranes, it is necessary to regularly maintain the cleanliness of electrical equipment such as contactors in control boxes to prevent the occurrence of leakage, breakdown, short circuits, and other phenomena.
• Check whether the contacts of the linkage console and contactor are sintered or not. If these conditions are found, they should be replaced in a timely manner or smoothed with sandpaper before use.
• When using hanging cables for conductivity, the rust and dirt on the guide rail of the trolley should be cleaned at all times to keep the traction pulley running normally.
• When using an overload limiter, it is important to regularly monitor the reliability of the control system and adjust the zero position as needed.