As an indispensable lifting equipment in industrial production, electric hoists play a crucial role in ensuring production efficiency and safety. Their stable operation is essential for maintaining the efficiency of work processes and preventing workplace accidents. However, various problems may occur during daily use, affecting their performance and even endangering the safety of operators. This article summarizes the common faults of electric hoists and their corresponding solutions to help users quickly diagnose and resolve issues to ensure safe and efficient operation.
6 Common Faults and Solutions for Electric Hoists
1. Abnormal noise during operation
The abnormal noise from an electric hoist usually indicates the onset of mechanical faults. For example, issues with the motor or gearbox can also cause abnormal sounds. Paying regular attention to operating noise helps detect issues at an early stage.
Motor Noise
When the noise originates from the motor, stop the hoist immediately. Check if the bearings are damaged, the rotor is scraping, there is single-phase operation, or misalignment. Just like human diseases, mechanical faults usually show external symptoms:
Gearbox Noise
Gearbox noise is usually caused by wear of one or more components:
Check if the lubricant has been replaced regularly. If not, replace the oil first. Inspect whether the gears are damaged or the bearings are deformed, and replace parts as needed.
2. No response from the electric hoist when the switch is pressed
This is one of the most common problems, mainly caused by three reasons:
Be sure to confirm that the power supply is connected. This is the most common oversight.
Overheating caused by long-term use or mechanical impact may lead to damage to internal wires or loose connections. Check if the wires are burned or disconnected.
If the power supply voltage to the motor is more than 10% lower than the rated voltage, the hoist will not be able to lift the load. Use a voltmeter to measure the voltage, and restart the hoist only after ensuring the voltage is within the acceptable range.
3. Hoist fails to stop after operation
If the electric hoist continues to run (either lifting or lowering to the limit) after the stop button is pressed, it is usually due to welded contacts of the contactor. The stop contacts cannot disconnect, so the motor continues to operate. In this case, cut off the main power supply immediately, and inspect or replace the contactor.
4. Hoist slips after stopping
Over time, electric hoists may experience slipping due to issues with the braking system:
Adjust the brake nuts in accordance with the instructions in the electric hoist manual. If necessary, replace the worn brake linings or springs. Dust and oil stains can also affect the brake; especially oil stains, which can cause excessive slipping. In some cases, if the motor coupling is stuck or moves improperly, the brake disc may not make proper contact with the end cover, resulting in unstable braking. Inspect and repair or replace the coupling accordingly.
5. Oil leakage from the gearbox
Oil leakage from the gearbox is usually caused by:
6. Motor faults
Long-term continuous operation may cause the motor to overheat due to overload or poor lubrication. Other problems include contactor faults, fuse failures, or wiring errors.
Common Motor Faults and Solutions
1). Overheating
2). Fuse blown or circuit breaker tripped
Check the rated current and replace the fuse or reset the circuit breaker as needed.
3). Phase wiring error or phase loss
Correct this by reversing two phases.
4). Broken power/control wires or poor connections
Repair or replace the faulty wires.
5). Blown control circuit fuse
Replace with a fuse of the correct type.
6). Low power supply voltage
Use a voltmeter to check if the voltage is more than 10% lower than the rated value.
7). Motor buzzes but does not rotate
Check the motor phase sequence and insulation, then make repairs.
8). Contactor faults
9). Emergency stop activated
Investigate and release the emergency stop button.
10). Contactor coil fault
Replace the coil or the entire contactor.
11). Rotor-stator rubbing (“rotor scraping”)
Usually caused by excessive wear of the support ring or rotor misalignment. Stop the hoist, replace the support ring, readjust the rotor-stator gap, or send the motor to a professional maintenance institution.
Summary
The safe and efficient operation of electric hoists depends on proper use and regular maintenance. Timely detection and resolution of problems can extend the service life of the equipment, maintain smooth production, and ensure workplace safety. For complex or unsolvable problems, it is strongly recommended to consult professional technicians for inspection and maintenance. A well-maintained electric hoist not only ensures operational safety but also plays a key role in improving overall productivity.
