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Overhead cranes are essential in industrial production, and the reliability of their hoisting mechanisms is key to safety and efficiency. Understanding overhead crane hoisting mechanisms failures and repair methods helps extend equipment life and improve productivity. This article explores common failures in hoisting mechanism components, analyzes their causes, and provides practical repair solutions.
Failures | Causes | Tamirat |
---|---|---|
Failure to lock the brake wheel (load fall down) | The hinge of the lever is jammed | Eliminate the jamming fault and apply lubrication |
Oil on the brake wheel and friction shim | Clean off the oil dirt | |
Lack of travel distance of magnet iron core | Adjust brake | |
The brake wheel and friction shim have heavy abrasive wear | Replace friction shim | |
Main spring loose or damage | Replace the main spring and nut | |
Lock nut and lever loose | Fasten lock nut | |
The hydraulic thruster impeller does not work | Check the electrical part of the thruster | |
The brake fails to release | Magnetic wire burns down | Replace |
Disconnection of wire to magnetic conductor | Connect the wire | |
Shoe block on braking wheel | Clean with kerosene | |
Gemel stuck | Eliminate the lock and lubricate it | |
The main spring force is too large or configuration is too heavy | Adjust the main spring | |
Push bar inflected, can not move the magnetic iron (hydraulic push bar break) | Straighten the mandril or change the mandril | |
Improper oil application | Change oil according to working condition | |
Impeller is locked | Adjust the push rod and check electrical part | |
85% lower than the rated load, magnetic force is not enough | Find out the reason for voltage reduction to eliminate the trouble | |
The brake is overheating, the friction pads emit a burnt smell, and they are wearing out quickly | The shoe can’t fully disengage the braking wheel when breaks loose, so causes friction | Adjust clearance |
Asymmetrical distance from shoes to braking wheel | Adjust clearance for two brake | |
Supporting spring damage or bending | Replace or repair the spring | |
The rough surface of the brake wheel | Turning the surface of the brake according to the requirements | |
The brake is easy to deviate from the adjusted position, and the breaking torque is not steady | The fastening nut is loose. Screw thread damage. | Fasten nut. Replace it. |
Magnetic overheat or abnormal noise | Main spring is over pressed | Adjust to proper extent |
Push bar is blocked | Eliminate the block and make lubrication | |
Wrong position of iron core and mandrel | Leveling fitting surfaces |
Failures | Causes | Tamirat |
---|---|---|
Periodic gear chatter phenomenon, particularly noticeable in the driven gear | Section distance error, gear side clearance beyond tolerance | Repair, re-install |
Severe metal friction sound, reducer shake, shell tinkers. | Gear backlash that is too small, gear axes are not parallel, gear has sharp edges | Adjust, re-install |
During gear meshing, there is an uneven knocking sound, and the housing vibrates | Teeth surface is not flat, teeth with flaws, gear contact surface is not completely clenched, but contact on one angle | Replace gear |
Shell heating especially the place where the bearing installation | Bearing damage | Replace bearing |
Bearing neck is stunk | Replace bearing | |
Gear teeth wear | Replace gear | |
Lack of lubrication oil | Replace lubrication oil | |
Oil leakage of subdivision surfaces | Seal failure | Replace sealing parts |
Shell deformation | Check subdivision surfaces, and replace them when heavily damaged | |
The subdivision surfaces are not flat | Subdivision surface levelled | |
Connection bolt loose | Clear the return chute and tighten the nuts | |
Reducer shake on base | The anchor bolt is loose | Adjust anchor bolt |
Shaft centerlines do not align | Adjust the diagonal alignment | |
Base rigidity is not enough | Reinforce base and increase rigidity | |
Heating of reducer | Too much oil | Adjust oil level |
Failures | Causes | Tamirat |
---|---|---|
The wire rope wears out quickly or frequently gets damaged | The diameter of the pulley and drum is too small | Replace the wire rope with one of better flexibility, and increase the diameter of the pulley and drum |
The wire rope dimensions do not match the groove of the drum; it is too small. | Replace the wire rope with one of equal lifting capacity but smaller diameter, or replace the pulley and drum | |
Dirty and lacking oil | Clean and lubricate | |
Incorrect installation of the lifting baffle, causing frequent rope abrasion | Adjust | |
The pulley groove and wheel edge are not smooth and have defects | Grind the defective areas manually | |
Some pulleys cannotrotate | Bearing lacks oil, dirt and corrosion in bearing | Lubricate, clean |
Failures | Causes and Result | Tamirat |
---|---|---|
Fatigue cracks on the hook surface | Overload, prolonged use, or material defects | Replace it if any cracks are found |
Wear of the opening and dangerous sections | Lessen the rigidity, or it is easy to cause hook break and accident | Replace hook when the abrasion over 5% of the dangerous section |
Permanent deformation occurs at the open areas and bend points | Caused by long time overload and fatigue | Replace immediately |
Failures | Causes and Result | Tamirat |
---|---|---|
Distortion of hook | Long time overload, and it is easy to cause hook break | Replace |
Surface has fatigue crack | Overtime, overload and hook damage | Replace |
The abrasion of pin shaft is more than 3%-5% of nominal diameter | Hook fall off | Replace |
Eye has crack or burr | Eye breakage | Replace |
The abrasion of eye’s lining reaches 5% of original thickness | Bad forced condition | Replace |
Failures | Causes and Result | Tamirat |
---|---|---|
Breakage, knotting, abrasion | Cause of breakage of rope | Stop using it when wire rope break and knot, replace according to standard when thread break, and replace the wire rope according to standard when it has abrasion |
Uneven wear of pulley rope grooves | Material asymmetry, bad installation and bad connection of rope and wheel | Replace it when abrasion of groove’s wall reaches 1/5 of previous thickness, and gauge ware reaches 1/2 of wire rope diameter |
Pulley can not rotate | Shaft damage or bearing damage | Replace the shaft and bearing and then lubricate and maintain them |
Pulley incline or loose | Keeper of shaft loose or wire rope hop out of groove | Fasten the keeper and repair the wire rope’s hopping |
Crack of pulley or break of wheel flange | Pulley damage | Replace |
Failures | Causes and Result | Tamirat |
---|---|---|
Drum has fatigue crack | Break of drum | Replace drum |
Abrasion of drum’s shaft and key | Break of shaft and cause the load fall off | Stop using and inspect the shaft key immediately |
Groove abrasion and rope hopping. The abrasion reaches 15%-20% of the original thickness | The rigidity of drum becomes weaker and easy to break. And wire rope is twisted | Replace the drum |
Failures | Causes and Result | Tamirat |
---|---|---|
Gear teeth break | Abnormal noise during operation, if continued to use, will damage the transmission mechanism | Replace the new gear |
Abrasion of gear reaches 15%-20% of the original teeth thickness | Impact and vibration occured during working and then damage the transmission mechanism | Replace the new gear |
Gear crack, gear key groove damaged by rolling of key | Vibration and noise caused by overtime use and improper installation, which make load fall off | For lifting mechanism, replace them, for traveling mechanism, repair or renew the key |
The spalling area of the tooth surface reaches 30% of the total working surface, and the spalling depth reaches 10% of the tooth thickness, carburized layer abrasion reaches 80% of the tooth thickness | Overtime use | Replacement: For reducers with a circumferential speed > 8 m/s, the high-speed gears should be replaced in pairs when worn |
Failures | Causes and Result | Tamirat |
---|---|---|
Crack | Poor material quality and improper heat treatment lead to shaft damage | Replace |
The shaft bend exceeds 0.5mm/m | Cause damage to shaft neck and influence the transmission and cause vibration | Change or rectify |
Damage of key groove | Unable to transmit torsion | For the lifting mechanism, replace them, for the traveling mechanism, repair them |
Failures | Causes and Result | Tamirat |
---|---|---|
Wheel tread and wheel flange have fatigue crack | Damage of wheel | Replace |
Uneven abrasion of drive wheel tread | Leads to rail gnawing and tilt of crane | Replace in pairs |
Abrasion of tread reaches 15% of wheel flange thickness | Vibration when traveling, damage to wheel | Replace |
Wheel flange abrasion reaches 50% of the original thickness | Caused by the crane tilt and rail gnawing, increases the risk of derailment | Replace |
Failures | Causes and Result | Tamirat |
---|---|---|
Fatigue crack on lever | Brake fails to work | Replace |
Fatigue crack on spring | Brake fails to work | Replace |
The abrasion of minor shaft and mandrel reaches 3%-5% of the nominal diameter | Fails to brake | Replace |
The abrasion of brake wheel reaches 40%~50% of the original wheel flange thickness | Load fall off or crane slide | Replace |
Brake shoe friction shim wear 2mm, or to 50% of original thickness | Bad break | Replace friction shim |
Failures | Causes and Result | Tamirat |
---|---|---|
Crack on coupling | Damage of coupling | Replace |
Loose in connection bolts | Impact and vibration during braking/starting will cause bolt reakage and falling of load | Tightened |
The gear teeth of the gear coupling are worn or broken | Lack of lubrication, heavy workload, start oppositely will lead to damage to the coupling | For the lifting mechanism, when the abrasion of gear teeth reaches 15% of the original thickness, replace it, and for the traveling mechanism, when the abrasion of gear teeth reaches 30% of the original thickness, replace it |
Press or deformation of the key groove | Cannot transmit the moment of torsion key falls off | For lifting mechanism, replace them, for other mechanisms, repair them |
Abrasion in shaft, pin and rubber ring etc | Strong impact and vibration occur during starting and braking | Replace worn parts |
Failures | Causes and Result | Tamirat |
---|---|---|
Temperature is too high | Lubricating oil dirt | Clean dirt, replace bearing |
Completely lack of oil | Add lubrication oil as required | |
Abnormal noise | Too much oil | Check the quantity of labricantion |
Dirty bearing | Clean dirty | |
Metal grinding noise | Lack of oil | Add oil |
Topping or impact sound | Damage of coupling support, rolling body | Replace bearing |
Failures | Causes and Result | Tamirat |
---|---|---|
Overheating | Incline of bearing and press to tight | Eliminate misalignment and ensure proper fastening |
Improper clearance | Adjust clearance | |
Lack of lubrication | Add lubrication | |
The lubricant quality is substandard | Replace with a qualified lubricant |