The following is an analysis and improvement suggestions on common faults of lever hoists (taking electric hoists as an example), covering the fault phenomena, causes, and treatment measures of key components such as electric motors, brakes, and operating mechanisms:

1、 Motor malfunction

1. The motor cannot start when unloaded

Reason for malfunction:

The power supply is not connected or the voltage is too low.

Button malfunction, poor contact, or failure of components (such as fuses and contactors) inside the electromagnetic switch box.

The limiter is not reset or the button wiring is broken.

Improvement suggestions:

Check the power supply to ensure that the voltage is stable and meets the rated value (such as using a multimeter to measure the input voltage).

Repair or replace damaged electrical components (such as buttons, contactors).

Adjust the position of the limiter or reconnect the button wire.

2. Rotate when unloaded, do not rotate when loaded

Reason for malfunction:

The broken rotor bars or uneven thickness of cast aluminum bars result in the motor being unable to output sufficient torque.

Single phase operation of the motor (such as loose or open wiring).

Improvement suggestions:

Replace the motor to solve the problem of rotor bar breakage.

Check and rewire to ensure that the three-phase power supply is functioning properly.

3. Difficulty starting the electric motor, high noise or abnormal sound

Reason for malfunction:

Overloading or low power supply voltage can result in insufficient starting torque.

The brake is not completely disengaged, increasing frictional resistance.

Wiring or electromagnetic coil breakage, or low insulation level (such as external damage to enameled wire, poor insulation between ties).

Improvement suggestions:

Lift according to the specified load to avoid overloading.

Adjust the power supply voltage to the rated value and check the brake clearance to ensure complete disengagement.

Repair broken wiring or electromagnetic coils, strengthen insulation measures (such as replacing enameled wires, reinforcing insulation between ties).

2、 Brake malfunction

1. When heavy objects slide or run, it is obvious that the vehicle cannot be stopped

Reason for malfunction:

The brake clearance is too large, resulting in insufficient braking force.

The brake ring is severely worn and has reached the scrap standard but has not been replaced.

Improvement suggestions:

Adjust the brake clearance to the specified range.

Replace worn brake rings to ensure reliable braking performance.

2. Scream when braking

Reason for malfunction:

Poor contact between the brake wheel and brake ring, resulting in relative friction.

The inclined lifting operation causes uneven force on the brake.

Improvement suggestions:

Adjust the brake again to ensure that the taper of the brake wheel matches that of the brake ring (for tapered brakes).

Strictly follow the operating procedures for lifting and avoid inclined lifting.

3、 Operating mechanism malfunction

1. Active wheel slip during startup

Reason for malfunction:

There are impurities such as oil and water on the track surface or wheel tread, which reduce the friction coefficient.

Poor wheel assembly accuracy (such as the "three legged" phenomenon), or too little active wheel pressure or suspension.

Improvement suggestions:

Remove dirt from the track surface and wheel tread, and if necessary, sprinkle sand on the top surface of the track to increase friction.

Improve the quality of wheel assembly or eliminate the "three legged" phenomenon by flame straightening the bridge frame.

2. Non synchronization, twisting or lateral sliding during starting and braking

Reason for malfunction:

The significant difference in the diameter of the wheel tread leads to asynchronous walking.

The brake clearance of the separately driven brake motors varies greatly, which affects coordination.

Improvement suggestions:

Replace wheels with inconsistent diameters to ensure synchronized walking.

Adjust the brake clearance of the two side drive motors by the same personnel to ensure consistency.

3. During operation, there may be tilting, deviation, gnawing or wear on the track

Reason for malfunction:

Poor quality of track installation (such as excessive span and elevation differences).

The geometric accuracy of the crane bridge is poor (such as large span and diagonal differences).

Improper fit between the width of the wheel groove and the width of the rail top surface, or significant difference in wheel diameter size.

Improvement suggestions:

Check and adjust parameters such as track span and elevation difference to ensure compliance with standards.

Check the span, span difference, and diagonal difference of the crane, and perform bridge correction if necessary.

Adjust the clearance between the wheels and the track, or replace wheels with different diameters.

4、 Other common faults and improvement suggestions

1. Steel wire rope malfunction

Reason for malfunction:

The malfunction of the lifting limiter resulted in the wire rope being pulled apart.

Overloaded excessively or the steel wire rope has reached the scrap standard and continues to be used.

The inclined suspension caused disorderly ropes, and the steel wire rope entered the gap at the end of the drum and was squeezed and deformed.

Improvement suggestions:

Repair or replace the limiter to ensure its sensitivity and reliability.

Lift according to the specified load and replace scrapped steel wire ropes in a timely manner.

Install a rope guide to avoid inclined lifting operations and prevent rope disorder.

2. Flashlight door (button switch) malfunction

Reason for malfunction:

The button spring is fatigued and damaged, resulting in the inability to reset when pressed.

Excessive dust and dirt can affect the contact performance of the button.

The hanging cable or wiring is loose, or the power phase sequence is connected incorrectly.

Improvement suggestions:

Replace the fatigued button spring to ensure that the button reset function is functioning properly.

Regularly clean the flashlight door to keep its surface clean and free of dirt.

Check and tighten the suspension cable, correct the problem of incorrect power phase sequence connection.

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment