Suggestions on Management Measures in The Middle and Mater Stages of The Life of Port Lifting Equipment

With the vigorous development of the industrial Internet, digitalization, intelligence, and unmanned operation have become the development trends of port lifting equipment. The following problems are common in the middle and late stages of the equipment’s life cycle (use time 10 years and above):

1. Equipment operation damage problem. The safety hazards of lifting equipment itself mainly come from a series of problems such as wear, corrosion or looseness of equipment parts after long-term heavy-load use.

2. The problem of equipment failure not being discovered in time. In the equipment management of automated and semi-automated terminals, due to the poor on-site working environment and the danger of high-altitude operations, port companies have gradually reduced personnel on-site operations and switched to remote control, automatic control and other methods. However, in remote control and automated operating environments, equipment operators cannot sense sudden vibrations, abnormal noises, etc. of the equipment, and cannot deal with emergencies immediately.

3. Equipment management system issues.

The equipment management system has not been effectively implemented, and some staff lack relevant equipment operation and maintenance experience or lack of enthusiasm and initiative, which is also detrimental to the safe operation of the equipment.

The importance of management and maintenance of port lifting equipment

1. Improve equipment operation efficiency and quality

Lifting equipment plays a vital role in ports, and lifting equipment management is one of the core tasks of modern ports. This work not only affects the port’s work efficiency, but is also directly related to the port’s economic benefits. A reasonable equipment management and maintenance system can provide good support for equipment to operate at full speed, and a good spare parts system can provide a sufficient buffer period for vulnerable equipment.

2. Optimize equipment operation monitoring and extend life

In order to enable the equipment to operate stably for a long time and ensure operation quality and efficiency, real-time monitoring of various equipment must be achieved. Managing and maintaining equipment based on detection data can not only optimize equipment operating performance and reduce the probability of failure, but also reduce the wear rate in long-term high-load operations, helping to extend the service life of equipment.

Common problems of port lifting equipment

1. Problems with the cart mechanism and track system

The cart mechanism bears the load of the entire equipment. During long-term heavy-load operation, when the wheel tread is in poor contact with the track, rail chewing is likely to occur, aggravating wheel wear. The bearings of the wheels of the cart mechanism are prone to failure under low-speed and heavy-load operating conditions.

Different solutions need to be developed for different reasons of the break of the wagon mechanism and the track. To solve the problem of geological structure settlement, the rolling method can be adopted, that is, the stable open-rock is used in the construction process to backfill the track foundation, and the foundation part is used to blow fill. On the basis of controlling the depth of backfill reasonably, the overall performance of the structure is strengthened. In the construction process, according to the construction requirements of railway foundation, the construction area is rolled by layers with vibration equipment to ensure that the compaction degree meets the quality standard, and effectively avoid the problem of track fracture caused by uneven settlement; In view of the problems arising in the welding process, the construction process requirements of track welding should be strictly implemented, mainly including: improving the welding rod baking process; Heat preservation and heat treatment after welding; Regular inspection of welding locations, etc.

2. Trolley mechanism and track issues

The trolley mechanism is one of the core components of yard bridges and quay cranes. During operation, the trolley mechanism will move on the main beam of the crane at high load and speed. There are the following common problems:

2.1 Car mechanism deviation

The problem of trolley mechanism deviation is that the trolley mechanism deviates from the predetermined track or path in the process of moving, resulting in severe friction between the horizontal wheel of the running part and the edge of the track.

The main causes of the trolley structure deviation problem are as follows: first, the uneven load of the lifting mechanism leads to the uneven load of the trolley mechanism; Second, the uneven lubrication on the track leads to different friction on both sides of the track; Third, the slope of the track increases due to the uneven settlement of the foundation, resulting in the lateral deflection of the trolley wheel. According to the above reasons, the solution is put forward: First, the manufacturing and installation accuracy of the track should be guaranteed, and the levelness of the trolley track should be checked during the on-site installation; Secondly, the wheels need to be lubricated regularly during use to reduce wear between the wheels and the track. When it is found that there is a deviation of the car mechanism, it must stop working immediately, and reposition the wheel to the specified position, and then restart the car after adjustment.

2.2 The horizontal wheel of the trolley mechanism falls off

During the operation of the horizontal wheel of the trolley mechanism, if the inside of the wheel severely squeezes the side of the track, it will not only cause damage to the wheel bearings, but also increase the resistance of the trolley operation, leading to an increase in motor energy consumption. When the track is severely squeezed, it may even cause the horizontal wheel to fall off, causing serious safety accidents.

In response to the problem of the horizontal wheel of the trolley mechanism falling off, the following solutions are proposed:

Check track quality. The manufacturing parameters of the trolley track have strict standards. The side flatness, spacing, and cross-section height difference of the track will significantly affect the operation of the trolley mechanism. For example, if the rails are unevenly spaced, the horizontal wheels of the crane trolley mechanism will pinch against the sides of the rails. Therefore, regular maintenance of the track should be carried out to check the condition and integrity of the track to ensure that the track surface is smooth and free of cracks, dents or other damage.

Check the braking mechanism. Failure of the braking system of the trolley mechanism will result in uneven braking force on both sides. Excessive or insufficient braking force on one side will intensify the squeeze on the side of the track. In order to ensure the working efficiency and quality of the main trolley brake, the brake must be adjusted, including the clearance and other parameters, which must meet the design requirements.

2.3 Pulley failure

The pulley is one of the important components of the equipment transmission system. The wear of the pulley bearings and pulley grooves will cause the pulleys to make abnormal noise or fall off, which may cause safety accidents in severe cases. Common causes of pulley failure are as follows:

Wear failure

Wear is one of the main causes of pulley failure. During the lifting process, the relative sliding or rolling between the crane pulley and the wire rope causes friction, resulting in damage to the wheel groove. The effect of horizontal wind load will also cause the steel wire rope to often shake horizontally, and the steel wire rope and the pulley will experience horizontal strain, resulting in the deterioration of the stress condition of the pulley. In order to minimize the impact of wear on the pulleys, grease should be added to the wheel grooves regularly and the lubrication effect should be checked.

Corrosion failure

Since port lifting equipment has been exposed to high salt and high humidity environments for a long time, chemical corrosion gradually damages pulleys and bearings. In order to reduce the impact of corrosion on the pulley, the integrity of the paint on the pulley surface must be regularly checked. If the paint is found to be peeling off, it should be repainted in time to prevent further deterioration of corrosion.

Failure due to overload.

When the lifting equipment is overloaded, huge instantaneous forces will be generated during the lifting process. If the endurance limit of the crane pulley is exceeded, the possibility of damage to the pulley increases dramatically. In order to avoid this problem, the working system should be strictly followed to prevent overloading during the operation of the equipment.

3. Lifting mechanism problem

Wire rope wear

The load conditions that steel wire ropes bear are characterized by multiple heavy loads, large impacts, and long cycles, which can easily cause problems such as wire rope wear and wire breakage.

The wear of the wire rope can be divided into external wear and internal wear.

External wear refers to the friction between the steel wire rope and the rope groove of the pulley or drum under pressure, causing surface wear of the steel wire on the outer strands of the steel wire rope. During the process of hoisting acceleration or deceleration, the friction between the wire rope and the side will increase, which will also lead to accelerated external wear. For external wear, the single-circle wear of the wire rope should be changed to uniform wear throughout the entire circumference, and the wear should be as uniform as possible over the entire length.

Internal wear refers to the wire rope through the reel or pulley to bear all the load pressure on the inside of the wire rope, at the same time due to the bending of the wire rope, the steel wire inside the wire rope will produce mutual force and slip, at this time the contact stress between the strands increases, the steel wire between the adjacent strands produce local indent deep concave. For internal wear, the point contact wire rope should be avoided as far as possible, the surface contact wire rope is preferred, followed by the line contact wire rope, and the appropriate drum or pulley should be used. Internal wear can also be reduced by allowing the wire rope to run empty for a period of time to achieve full running-in.

Container spreader reliability issues. The twist lock mechanism is the core device for connecting the spreader to the container. Damage to the twist lock will cause the container to fall off during movement. Therefore, the safety of the twist lock mechanism needs to be strictly checked, and it must be replaced immediately when cracks are found.

4. Transmission system problems

The transmission system of lifting equipment is responsible for transmitting the power generated by the electric motor or other power source to various mechanical components and controlling the direction and speed of the mechanism’s movement. Common faults in the transmission system mainly occur in two places: bearings and gears.

Bearing failure

The main phenomena of bearing failure are abnormal noise and overheating. When abnormal noise occurs, harsh metal friction sounds and regular or irregular impact sounds can be heard at the equipment site. Abnormal noise will occur when there are impurities (metal powder) in the bearing lubricant or the bearing is damaged. Once abnormal noise is found during maintenance, corresponding measures should be taken according to the cause of the fault, such as adjusting the bearing installation position or replacing grease. If the bearing is damaged beyond repair, work should be stopped and the bearing should be replaced. Overheating occurs when the operating temperature of the bearing exceeds the allowable temperature. The cause of overheating may be improper assembly of the bearing, misalignment of the bearing holes at both ends, or abnormal contact between the balls and the inner and outer rings. Reasons such as the fit between the inner ring of the bearing and the journal is too loose or too tight, the fit between the outer ring of the bearing and the bearing hole of the end cover is too loose or too tight, the inner ring of the bearing cover is eccentric, etc. will also increase the friction area of the bearing, leading to overheating failure.

Gear failure

The gear is the key transmission part of the reduction box, and its function is to realize power transfer and speed regulation through the gear transmission mechanism. However, under low-speed, heavy-load working conditions, gear components will be subjected to huge alternating stress and friction, which is very detrimental to maintaining the integrity of the gear surface. After long-term operation, slight wear on the gear surface will induce pit defects on the tooth surface. At the same time, the metal powder produced by wear will reduce the lubrication effect, causing cracks or fractures in the gear, causing the reduction gearbox to malfunction and shut down. Therefore, in order to ensure the reliability and stability of the reduction gearbox, the lubricating oil and gears must be checked regularly, and worn gears must be replaced in time.