Common Local Faults and Troubleshooting Methods of Bridge Cranes

Crane refers to a multi-action lifting machinery that lifts vertically and carries heavy objects horizontally within a certain range. Bridge crane is a kind of lifting machinery widely used in industrial and mining enterprises. Whether it can work normally directly affects the completion of locomotive maintenance tasks and the safety of people and equipment.

Hook

The hook is the most used by the bridge crane taking device, it bears the whole load of lifting, in the process of use, once the hook is damaged and broken, it is easy to cause a major accident. The reason for the damage and fracture of the hook is the crack, deformation, damage and fracture of the hook due to friction and overload. In order to prevent the failure of the hook, it is necessary to strictly prohibit overload lifting during use, pay attention to the opening degree of the hook and the wear of the dangerous section during the inspection process, and regularly anneal the hook. Once the crack is found, the hook should be scrapped in accordance with the relevant regulations, and resolutely do not weld the hook. Special equipment management personnel to check the hook in accordance with the requirements of the rules to determine whether the hook can be used.

Wire rope

1. Fault analysis

During the operation of the steel wire rope, the stress of each steel wire rope is very complicated, because of the different positions of the steel wire in the rope, some in the outer layer and some in the inner layer. Even by the simplest tensile force, the force distribution between each steel wire rope is different, in addition, when the steel wire bypassing the coil and pulley, bending stress, extrusion pressure between the steel wire and the steel wire, so it is difficult to accurately calculate its force, generally using the static calculation method.

The main reason of wire rope breakage is overload, but also related to the number of times in the pulley and drum, every time the wire rope is worn around the process of straight bending and then straight bending, the more the number of times it is easy to damage and break; Secondly, the breaking of the wire rope is related to the diameter of the bypass pulley, the drum, the working environment, the type of work, and the maintenance.

2. Preventive measures

(1) The lifting capacity of the crane during operation should not exceed the rated lifting capacity.

(2) The wire rope of the crane should be selected according to the type of work and environment.

(3) The wire rope must be lubricated regularly (the lubrication cycle shall be determined according to the working environment).

(4) Do not subject the wire rope to sudden impact when the crane is operating.

(5) Steel wire ropes in environments with high temperatures and corrosive media must have isolation devices.

Reducer gear

1. Fault analysis

Reducer is an important transmission part of the bridge crane, through the gear mesh to transfer torque, the motor high-speed operation to the required speed, in the process of transferring torque gear will appear tooth break, tooth pitting, tooth surface glue, tooth surface wear and other mechanical failures, resulting in gear failure reasons are as follows:

(1) Short time overload or impact load, repeated bending caused by fatigue break;

(2) The tooth surface is not smooth, there are raised points to produce stress concentration, or the lubricant is not clean;

(3) Lubrication failure due to high temperature;

(4) Wear is caused by hard particles entering the friction surface.

2. Preventive measures

(1) The crane cannot be used for lifting, starting and braking must be slow and smooth, and sudden reverse movement is prohibited unless under specific circumstances.

(2) The lubricant must be replaced in time, the casing must be clean, and the appropriate type of lubricant must be selected;

(3) Always check whether the lubricating oil is clean; if it is found that the lubricating oil is not clean, replace it in time.

Drum and wire rope pressure plate

The drum is an important stress-bearing component of the crane. During use, drum wall thinning, holes and fractures may occur. The cause of these failures is that the drum and wire rope are in contact with each other and rub against each other. When the drum is thinned to a certain extent, it will break because it cannot withstand the pressure exerted by the wire rope. In order to prevent the occurrence of mechanical accidents such as drums, according to national standards, the drum wall should be replaced in time when the wear reaches 20% of the original value or cracks appear. At the same time, pay attention to the operating environment and lubrication of the drum and wire rope.

Brake

1. Fault analysis

The brake is an important safety component of the bridge crane, which can prevent the suspension from falling and realize the parking function. Only the intact brake can ensure the accuracy and safety of the crane operation. In the crane operation, the brake will have insufficient braking force, sudden brake failure, high temperature of the brake wheel and smoke of the brake gasket, and the brake arm will not open. The causes of these mechanical failures are analyzed as follows:

(1) Excessive wear of brake belt or brake wheel; Brake with a small piece of local shedding; The main spring is too loose; There is oil dirt between brake belt and brake wheel; There are stuck places outside the movable hinge or parts with excessive wear; The lock nut is loose and the tie rod is loose. Hydraulic push rod release brake impeller rotation is not flexible;

(2) Brake gaskets are seriously or large pieces off, or long-stroke electromagnets are stuck, the main spring fails, or the main components of the brake are damaged;

(3) The gap between the brake and the gasket is adjusted too large or too small;

(4) The hinge is stuck or the braking torque is adjusted too much, or the hydraulic push rod release brake cylinder is short of oil and mixed with air, or the oil used by the hydraulic push rod release brake does not meet the requirements, or there is dirt between the brake disc and the brake wheel.

2. Preventive measures

The brakes should be inspected and maintained regularly. The brakes of the hoisting mechanism must be once per shift, and the brakes of the operating mechanism must be inspected once a day. Mainly check the following:

(1) Is there any jamming and wear at the hinges, and is there any looseness in the fastening parts;

(2) Whether the movement of each moving part is normal;

(3) Whether the hydraulic system is normal;

(4) Check whether the wear between the brake wheel and the brake belt is normal and clean.

Determine whether the brake is normal based on the inspection, and resolutely prevent diseased operation. At the same time, the brake must be lubricated and maintained regularly. In order to ensure the safe operation of the crane, the brakes must be adjusted frequently to ensure the working requirements of the corresponding mechanism.

Wheels and Tracks

During the operation of the crane, common faults of the wheels and tracks are the gnawing of the wheels and the unequal height and slipping of the trolley. There are many reasons for gnawing, and the forms of gnawing are diverse. In mild cases, tunnel gnawing affects the life of the crane, and in severe cases, it can cause serious casualties. Therefore, special equipment managers must pay sufficient attention to tunnel gnawing.

The main causes of the gnawing are the non-conforming error and uneven friction during installation, and the excessive wear of the parts in the transmission system of the truck, and the excessive clearance of the key connection resulting in the braking asynchronism. Therefore, the special equipment competent department of each unit must find qualified units for installation and maintenance of the crane, so as to ensure the safety and operating life of the equipment; At the same time, special equipment management personnel should strengthen the usual inspection management, avoid the mechanical failure of the crane gnawing, in the inspection process to carefully and carefully find out the cause of gnawing, and take corresponding measures.

The unequal height of the car wheel is a very unsafe factor in the operation of the crane, and the unequal height of the car makes the car suspended in the operation of a wheel or the wheel pressure is too small may cause the vibration of the car body. The factors that cause the unequal height of the car wheel are caused by many reasons, but the main reason is that the installation error does not meet the requirements and the weight of the car design itself is not uniform, so the fault of the unequal height of the car should be comprehensively analyzed, and the problem of the unequal height of the car should be solved.

Crane in the process of operation due to the track is not clean, start too fast, the car track uneven, the wheel oval, the wheel pressure between the driving wheel unequal causes the car to produce a slip ring image, which requires special equipment management personnel must be careful in the inspection process, found that the problem should be solved in time to avoid the phenomenon of the car slipping.