Electric Hoist Troubleshooting Guide

To ensure the safe and efficient operation of the electric hoist, it is crucial to detect and address faults promptly. The following are diagnostic methods and solutions for six common problems, presented in simple language for quick reference.

1. Abnormal Noise During Operation

Abnormal noise is an early sign of mechanical failure and should be diagnosed based on the source and characteristics of the sound.

• Motor Noise

  • Characteristics and Handling:

    • Humming/Buzzing: Often indicates single-phasing (loss of a phase). Stop the hoist immediately and check the power supply and wiring.

    • Clunking/Scraping Sounds: Likely due to bearing damage or rotor scraping. Stop the hoist to replace bearings or realign the rotor.

    • Sharp Screeching/Squealing: Commonly caused by motor misalignment. Realign the motor installation.

  • Action Recommendation: If abnormal noise is detected, cut power immediately and have a professional technician inspect it.

• Gearbox Noise

  • Primary Causes: Gear wear, bearing deformation, or inadequate lubrication.

  • Troubleshooting Steps:

    1. Check if the lubricant is sufficient or contaminated; replace or top up promptly.

    2. Open the gearbox housing to inspect gears and bearings; replace any that are damaged or deformed.

       
       

2. No Response When Pressing the Switch

• Troubleshooting Steps (in order):

  1. Check Main Power Supply: Ensure power is on, circuit breakers are not tripped, and fuses are intact.

  2. Test Control Pendant: Check for loose connections, burnt, or broken wires in the control circuit.

  3. Measure Voltage: Use a multimeter to confirm the motor input voltage is not more than 10% below the rated voltage. Adjust the power supply if too low.

  4. Check Limit Switches: The hoist might be at the travel endpoint. Try operating it in the reverse direction.

     
     

3. Hoist Does Not Stop After Releasing Control

• Primary Cause: Welded contacts on the contactor, preventing the circuit from breaking.

• Emergency Action:

  1. Immediately cut off the main power supply to force shutdown.

  2. Replace the faulty contactor and check the control circuit for shorts or overloads.

     
     

4. Load Slipping / Brake Slippage

• Common Causes:

  • Worn brake linings, weakened springs, or loose adjustment nuts.

  • Oil contamination on the brake disc, reducing friction.

  • Stuck or faulty motor coupling preventing proper brake disc contact.

• Handling Methods:

  • Adjust the brake nuts or replace springs/linings according to the manual.

  • Clean brake surfaces of oil and dirt; keep them dry.

  • Check the coupling for smooth operation; repair or replace if necessary.

    
    

5. Gearbox Oil Leak

• Leak Points and Handling:

  • Worn/Damaged Seals: Replace oil-resistant seals.

  • Loose Housing Bolts: Tighten bolts evenly after the hoist is stopped.

  • Cracked Housing: Repair by welding or replace the housing.

    
    

6. Motor Faults

Motor faults vary; refer to the following list for troubleshooting.

1. Symptom: Motor Overheating

   • Possible Causes: Overloading, bearing damage, excessively small brake gap.

   • Solutions: Reduce load, replace bearings, adjust brake gap according to manual.

2. Symptom: Fuse Blows or Circuit Breaker Trips

   • Possible Causes: Short circuit or severe overload in the circuit.

   • Solutions: Locate and rectify the short circuit, then replace the fuse with one of the correct rating.

3. Symptom: Motor Buzzes but Does Not Rotate

   • Possible Causes: Loss of phase, seized rotor.

   • Solutions: Check power supply for missing phase; manually check if the rotor turns freely.

4. Symptom: Contactor Does Not Engage

   • Possible Causes: Faulty contactor coil, broken control wiring, low voltage.

   • Solutions: Check coil continuity, inspect and repair control circuit, ensure voltage is normal.

     
     

Summary of Maintenance Recommendations

• Daily Attention: Perform no-load test runs before operation; listen for unusual sounds; check braking effectiveness.

• Regular Maintenance: Lubricate moving parts, clean brakes, tighten bolts according to the manual.

• Safety First: If a fault cannot be identified or resolved, stop operation immediately, tag the hoist "Out of Service," and contact qualified technical personnel.

Standardized operation and regular maintenance significantly reduce failure rates, extend equipment service life, and ensure workplace safety.