The failure of a lever chain crane to operate may involve multiple system failures such as electrical, mechanical, hydraulic, etc., which need to be gradually investigated according to the logic of "from simple to complex, from common to rare". The following are specific solutions and corresponding methods:

1、 Basic Inspection: Power Supply and Circuit System

Power issue

Check whether the main power switch is turned on and whether the cable is damaged (such as measuring the current at the cable joint with an ammeter, locating the break point, and repairing it).

Confirm voltage stability (if the supply voltage is lower than 85% of the rated voltage and the electromagnetic attraction force is insufficient, it is necessary to troubleshoot the power grid or generator).

Control circuit malfunction

Check whether the controller contacts have poor contact (such as using a megohmmeter to detect the grounding part, repairing the open circuit, or replacing damaged contacts).

Check the setting value of the overcurrent relay (which should be adjusted to 2.25-2.5 times the rated current of the motor) to avoid false triggering caused by low setting values.

2、 Troubleshooting of mechanical components

Transmission system

Chain/gear: Check if the chain is broken, stuck or if the gear is worn (if the gear teeth are broken or the tooth thickness wear exceeds 15%, it needs to be replaced); Whether the lubricating oil has deteriorated (it is necessary to replace the gear oil and ensure that the oil level meets the standard).

Coupling: Check whether the coupling is worn or the keyway is damaged (if the gear teeth wear more than 30%, they need to be replaced in pairs, and if the keyway is crushed, it needs to be repaired or replaced).

braking system

Brake failure: Check whether the lever hinge is stuck, whether the brake wheel/friction plate is stained with oil or worn (need to clean the oil, replace the friction plate or adjust the main spring force).

Brake overheating: Confirm whether the gap between the brake shoe and the brake wheel is uniform (too small a gap can cause friction heating, and the gap needs to be adjusted to the standard value).

Rotating and lifting mechanism

Check if the arm extension and elevation adjustment mechanisms are stuck (such as hydraulic cylinder oil leakage or piston rod bending requiring maintenance); Check if the groove of the pulley system is unevenly worn (if the radial wear reaches 1/4 of the rope diameter, the pulley needs to be replaced).

3、 Hydraulic and safety devices

hydraulic system

Check whether the hydraulic pump/cylinder is abnormal (such as abnormal noise from the pump body, decreased oil pressure, disassembly and inspection of bearings or seals; insufficient output force of the hydraulic cylinder, inspection of sealing and replacement of seals).

Confirm whether the hydraulic oil is contaminated or insufficient (replace the hydraulic oil that meets the ambient temperature and replenish the oil).

safety device

Check if the limit switch and torque limiter are sensitive (if the main contactor does not release after the end limit switch is activated, it is necessary to repair the circuit breaker or adjust the wiring).

Verify whether the overload protection device is effective (such as when the load exceeds the rated value, the controller should block the output and sound an alarm).

4、 Special fault handling

Slipping hook/sliding down: Check if the brake main spring is loose and if the locking nut is tightened; If the brake wheel wear exceeds 1-2mm or the rim thickness wear exceeds 40%, the brake wheel needs to be replaced.

Motor abnormality: If the motor heats up and the three-phase current is unbalanced, it may be due to soft breakdown of the thyristor (the damaged thyristor needs to be replaced and the triggering circuit checked).

Noise/vibration: Check if the running wheels are deformed and if the bearings are lacking oil (replace the running wheels or bearings and replenish lubricating grease).

5、 Comprehensive testing and recording

After completing the repair, it is necessary to conduct no-load and load tests (such as lifting, rotating, and braking tests) to confirm that all mechanisms are operating normally and without abnormal noise.

Record the fault phenomenon, troubleshooting process, and repair measures, form maintenance files, and provide reference for subsequent fault analysis.

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