What are common bridge crane problems and how to solve your bridge crane problems?

bridge crane basic questions and solutions to ensure your bridge crane work more efficiently, safely and durably. 15 common problems on bridge crane control, hoisting system, crane braking, installation and braking, etc., and suggested solutions are presented for you.

Question 1: Why does Dongqi Crane use PLC on bridge crane?

Answer: PLC is the abbreviation of programmable logic controller. Its basic structure are composed of power, CPU, memory, input/output interface circuit, function module and communication module. PLC can change the form of relay-contacts control, and can make it adjustable for electric motors' speed of every file, acceleration time and braking time according to practical conditions. PLC functions include calculating, controlling, programming, communicating, diagnosing, processing.

Because PLC has various advantages and can make heavy duty bridge overhead cranes more safety and convenient, Dongqi Enterprise apply PLC in bridge crane system. Its advantages are following.

• Convenient use, simple program
• Strong function, highly cost-effective
• Complete hardware, convenient use for customers, strong adaptability
• High reliability, strong anti-interference capability
• Little work for system's design, installation and test
•  Little work for maintenance and convenient maintenance.

Question 2: What's the system of hoist bridge crane?

Answer: Electric hoist bridge crane mainly includes lifting mechanism, travelling mechanism (trolley travelling mechanism and bridge crane travelling mechanism) and rotating mechanism.

• First is lifting mechanism, it refers to electric hoist. It is composed of driving device (electric motor), braking device (brake), transmission device (reducer) and fetching rotating device (hook, grab, magnetic disc, and wire rope, chain, trolley, drum, sprocket and rope-guiding device).
• Second is horizontal travelling mechanism, it is trolley travelling mechanism. Travelling trolley is composed of electric motor, braking device (brake), transmission device (reducer) and trolley wheel device.
• Third is vertical travelling mechanism, it is bridge crane travelling mechanism. This mechanism includes driving mechanism (electric motor), braking device (brake), and transmission device (reducer) and bridge crane wheel device. The advantage of electric hoist bridge crane is that it adopts three-in-one driving device. It combines driving device (electric motor), braking device (brake) and transmission device (reducer) together. It is a compact and light driving device without shaft.

Question 3 : How do bridge cranes supply power ?

Answer: First is through flexible cable. The power of the lifting bridge crane is supplied by AC power system. Because the work of the bridge cranes is movable, the bridge crane and the power can't be connected in fixed way. In general, the flexible cable is used to supply the power. When the bridge crane system and the trolley move on the tack, flexible cable can stretch and roll along the track. Second is through slide wire and electric brush. Three phase AC power is transported into cabin's protection box through three main slide wires and electric brush, then transported to bridge crane system's motor, electromagnet and AC control station through wire way. Third is through auxiliary slide wire and electric brush. This refers to the power supply of magnetic brake, trolley's hoisting mechanism and trolley's motor.

Double grider bridge crane main girder

Question 4 : What to do when the bridge crane trolley line is out of power ?

Answer: The reason is that electric brush climbs in the conductor, the brush wears seriously, conductor joint is not smooth, single connector is used, rail joint becomes loose. The correct way is to check whether the brush wears seriously, change electric brush, adjust the connecting joint, and adopt double-brush connector.

Question 5: What to do when the guiding rail is deformation, the collector doesn't work?

Answer: The main reason is the temperature is too high, the distance between lifting racks is too long or loose. It is useful to adopt anti-heat plate partially, add sun shield outdoors, increase the number of trolley line lifting racks, correct the conductor and screw down the screws.

Question 6 : What to do when the bridge crane trolley line shakes seriously?

Answer: The reason is that fork can't absorb the transmission error, guiding-rail has poor straightness, and lifting rack is loose. The right way is to modify tractor, adjust the straightness of guiding-rail, and tighten the screw mounts.

Single girder bridge crane installation

Question7: What are the factors which influences bridge crane working speed?

Answer: bridge crane working speed includes lifting speed, trolley travelling speed, bridge crane travelling speed. Working speed is influenced by many factors.

• First, it is related to the weight. The bridge crane with small and medium lifting can adopt high speed to improve efficiency, the bridge crane with heavy lifting is suitable to choose low speed to reduce driving-power and improve travelling stability and safety.
• Working speed is also related to working class and working requirement. The bridge crane with high class, frequent use and high efficiency can adopt fast speed, working mechanism with low class and adjusting purpose can adopt low speed. The bridge crane only used for equipment installation and maintenance can choose low speed.
• According to practical needs, it can also adopt double speed (high and low speed), dead speed or adjustable speed. What's more, working speed is also related to working room. The bridge crane with long travelling distance, high lifting height is suitable for high speed. The bridge crane with short travelling distance is not suitable for high speed. With development of industry, the bridge crane with much transporting work mostly adopts high speed.
• The bridge crane used for installation and maintenance adopts adjustable speed. For some bridge cranes with special functions, such as the bridge crane for quench, should has fast-down device, for bridge crane with high lifting height, it should improve lifting speed, adopt low speed for heavy material, high speed for no-load, or high down-speed to increase efficiency. 

Question 8: What to do when the brake can't stop the braking-wheel?

Answer: The reasons are as following: the leverage hinge is stuck, braking-wheel and friction plate have oil pollution, electromagnetic core doesn't have enough travelling distance, braking-wheel and friction wheel are wearied seriously, main spring is loose and damaged, locking-nut and tie rod are loose. Make lubrication and exclude stuck fault, clean the oil pollution, adjust the brake, change the friction plate, change the main spring and locking-nut, tight the locking-nut, check the impeller driving mechanism.

Question9: What to do when the brake is too hot, the friction plate wears fast.

Answer: The braking-shoe is loose, it doesn't break off the braking-wheel totally, and causes friction. The gap between two braking-shoe and braking-wheel is not even, or the gap is too narrow. The assistant-spring of short distance brake damages or bends, the braking-wheel surface is very tough. What to do is to adjust the gap, change or maintain the assistant-spring, processes the braking-wheel surface. The reducer has uneven tapping and the machine cover vibrates when the reducer and gears mesh. Just change the gears.

Trolley travelling bridge crane

Question10: Why bridge crane system need buffers?

Answer: Three kinds of buffers are used widely, spring buffer, rubber buffer and hydraulic buffer. Spring buffer is reliable and convenient to maintain. Rubber buffer has simple structure. Hydraulic buffer can absorb large hitting energy and has no rebound effect. When limiting stopper of travelling extreme position or brake is in trouble, due to the inertia, the bridge crane system moving in the end or the trolley on the main girder, will hit against the stopper set in the position. But bridge crane buffer can absorb the travelling energy of bridge crane system or trolley and reduce impulsion. Buffers should be set between the bridge cranes travelling on the same track, or between the double trolleys on the same girder.

Question11: What is the anti-collision device on bridge cranes?

Answer: It mainly includes laser type, ultrasonic type, infrared type, electromagnetic type, all use the principle that light or radio wave travels, reflects and the distance can be measured. When two bridge cranes travels to pointed position, the bridge crane mechanism rings alarm bell and gives the stop command at the same time.

Question12: How does anti-deflection device protect bridge cranes?

It includes wire-rope type, cam type, chain wheel type and skew indicator and other automatic adjustable devices. When the bridge frame deflects to some degree, it can give signal to the operator and adjust itself automatically. When the bridge crane frame deflects seriously, it can cut the power automatically, stop the travelling mechanism and protect the safety.

Question13: What is the function of safety hook of bridge crane?

Answer: Safe hook is an important part of bridge crane. What are functions and types of safe hook?

Safety hook is mainly used for single girder bridge crane. Lifting material at one side of main girder, the material has a tilting torque against trolley, anti-tilting torque from vertical gauge wheel or horizontal gauge wheel can keep the trolley balance. But this kind of way can't ensure the safety under the condition of cyclone, outside impact, wheel broken, maintenance and repair. Thus this bridge crane should be installed with safe hook. According to trolley and wheel, safe hook has different structures.

10 ton bridge crane for sale

Question14: How to inspect the safe hook of bridge crane?

Answer: The inspection of the bridge crane safe hook is necessary. When the trolley travels along the main girder, there is no stuck between safe hook and rail or main girder web. Web has no weariness. The gap between safe hook and rail should meet the design requirement. Bolt is tight and on the right location, weld is seal, safe hook has no damage, such as abnormal deformed. Function check is the basic method, just through visual inspection and test operation.

Question15: how to lubricate the large and heavy bridge crane?

Answer: Lubrication is necessary for large bridge crane. Reasons to lubricate your bridge crane It can control friction, reduce weariness, down bridge crane temperature, avoid rust and form seal. These functions rely on each other and influence each other. If the friction can't be controlled, the weariness can/t be reduced, this will lead much friction heat and items high temperature, thus to damage the friction surface lubrication and lubricating material.

How to lubricate your bridge crane?

Some bridge crane parts should be lubricated regularly, such as shafts, holes and friction surface with relative move. Due to different working condition, the lubricating points are different. For various kinds of bridge cranes and different lubricating parts, every lubrication should meet the standards and requirement of instructions. It is good for bridge crane to make regular lubrication and check. Lubricating with qualified oil can ensure the bridge crane work normally and avoid early weariness. Bad oil can lead mechanical accident, even damages equipment, influences safe producing. Lubrication plays an important role in bridge crane's maintenance. The lubricating oil can influence the effect directly.

If you want to know more the bridge crane or overhead crane, or other Types of cranes, please feel free to contact us.