The inability to operate a chain crane may involve multiple factors such as mechanical failures, electrical system abnormalities, operational errors, maintenance deficiencies, or environmental factors, and requires systematic investigation. The following analysis will be conducted from four aspects: core fault types, specific manifestations, diagnostic logic, and solutions:

1、 Mechanical system malfunction

Chain and transmission mechanism issues

Chain jamming/breakage: Chain pitch exceeding tolerance (elongation>3%), chain link deformation, foreign object jamming (such as metal debris, dust), lubrication failure (thermal expansion jamming caused by dry friction).

Diagnosis: Manually rotate the chain and check for smoothness; Measure the pitch of the chain link and compare it with the factory standard; Check if the chain guide groove is worn or deformed.

Solution: Clean the chain and guide groove, apply special lubricating grease; Replace the out of tolerance chain; Adjust the tension of the chain.

Gear/pulley/bearing failure

Gear wear/poor meshing: gear tooth surface pitting, broken teeth, excessive tooth flank clearance; Damage to pulley bearings (abnormal noise, heating); The gearbox oil seal leaks oil, resulting in insufficient lubrication.

Diagnosis: Disassemble the gearbox and check the condition of the gear teeth; Measure the gear runout with a dial gauge; Check the bearing clearance and temperature rise.

Solution: Replace worn gears; Adjust the gear clearance; Replace bearings and replenish lubricating oil.

Brake failure

Brake stuck/unable to release: excessive wear of brake pads, failure of brake springs, oil leakage in hydraulic brake system; Improper adjustment of the brake (too tight to rotate, too loose to slide).

Diagnosis: Check the thickness of the brake pads (usually<2mm and need to be replaced); Test whether the brake release button is sensitive; Check whether the hydraulic pipeline leaks oil.

Solution: Adjust the tension of the brake spring; Replace the brake pads; Repair the hydraulic system.

2、 Electrical system abnormality

Motor/control circuit malfunction

Motor cannot start: power phase loss (three-phase motor), low voltage (<85% of rated voltage), short circuit/open circuit of motor winding, capacitor fault (single-phase motor); Control button/remote control damaged; Loose or burnt wiring terminals.

Diagnosis: Use a multimeter to check the power supply voltage and phase sequence; Measure the resistance of the motor winding; Check the continuity of the control circuit.

Solution: Repair the power supply circuit; Replace damaged motors or capacitors; Re tighten the wiring terminals.

Limit/safety protection device triggered

Limit switch malfunction: The upper/lower limit switches are triggered incorrectly or damaged, causing the equipment to be unable to continue moving; Overload protection devices (such as thermal relays, electronic scales) trip due to overload or malfunction; The emergency stop button was pressed but not reset.

Diagnosis: Manually trigger the limit switch and check if the action is reliable; Check the setting value and status of the overload protection device.

Solution: Adjust or replace the limit switch; Reset overload protection device; Check if the load exceeds the standard.

3、 Operation and maintenance related issues

operational error

Overload operation: exceeding the rated load, triggering overload protection or causing motor stalling; Wrong direction of operation handle (such as confusion between lifting and lowering directions); The safety lock has not been unlocked (such as the anti fall device not being released).

Diagnosis: Check the load identification and actual load; Observe the indication of the operating handle; Check the status of the safety lock.

Solution: Reduce the load to within the rated range; Correctly operate the handle; Unlock the security device.

Maintain deficiencies

Insufficient lubrication: The lack of lubrication in chains, gears, and bearings leads to dry friction and sticking; Lubricating grease ages and deteriorates, losing its lubricating effect.

Diagnosis: Check if lubricating grease is applied to the lubrication points; Use an oil gun to check if the lubrication channel is unobstructed.

Solution: Regularly replenish or replace specialized lubricating grease; Clean the old grease and re lubricate.

4、 Environment and external factors

Adverse environmental impact

High temperature/low temperature: High temperature causes motor overheating protection to start; Low temperature causes an increase in the viscosity of lubricating oil, making it difficult to start.

Dust/corrosion: Dust enters the gearbox, accelerating wear and tear; Corrosive environments cause metal components to rust (such as chains and hooks).

Solution: Install heat dissipation or heating devices; Regularly clean up dust; Apply anti-corrosion coating.

External object obstruction

Foreign objects get stuck: foreign objects get stuck in the chain guide groove or gearbox; Ground obstacles hinder the movement of equipment (such as foreign objects on the track).

Diagnosis: Check for obstacles around the device and its movement path.

Solution: Clear obstacles; Adjust the device position.

5、 Suggestions for troubleshooting process

Preliminary inspection: Observe the appearance of the equipment for any obvious damage (such as chain breakage, oil leakage); Check if the power supply and control buttons are functioning properly.

Manual testing: Rotate the chain or gear manually to check for any jamming or abnormal noise.

Electrical testing: Use a multimeter to test the power supply voltage, motor winding resistance, and control circuit continuity.

Mechanical disassembly: If internal faults are suspected, disassemble the gearbox or brake and check the status of internal components.

Professional maintenance: If unable to solve the problem on your own, contact the equipment manufacturer or professional maintenance team for in-depth inspection.

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