What are the causes of abnormal noise during the lifting and lowering of hydraulic cylinders?

Causes of Abnormal Noise During Operation of Hydraulic Lifting Platforms

When using a hydraulic lifting platform, abnormal noise may occur due to various reasons. Abnormal sounds and increased noise in hydraulic lifts can generally be attributed to three main causes:

I. Noise Caused by Hydraulic System Malfunctions

1. When noise originates from the cylinder:
   Possible cause: During manufacturing, the rod was processed with the upper tolerance limit while the cylinder tube was processed with the lower tolerance limit, resulting in a dimensional mismatch between the rod and cylinder sleeve.
   Solution: Disassemble the cylinder, remove the rod, and re-lathe the rod to the correct dimensions.
2. When noise originates from the power unit:
   You need to check if any outlet ports are blocked, causing poor oil flow.
   Solution: Run the electric motor until the oil temperature rises, then clean out any impurities blocking the ports. Refill the system with high-quality hydraulic oil.

II. Noise Generated by the Lifting Mechanism Structure

1. Noise from lack of lubrication in pivot points:
   Increased noise during lifting/lowering may be caused by insufficient lubrication in the bushings or shafts connecting the support arms or rods.
   Solution: Apply lubricating oil to the affected joints.
2. Noise from worn or deformed rollers:
   Rollers on the upper or lower platforms may be severely worn, deformed, or have poor surface smoothness, causing loud noise when moving in the guide groove.
   Solution: Replace with qualified rollers. If the guide groove surface is rough, also treat the guide groove surface.

III. Noise Caused by Electrical Equipment or Component Failures

1. Chattering AC contactor in the distribution box during startup:
   Cause: Voltage mismatch or undersized cables leading to insufficient current, failing to meet design requirements. This causes the moving contacts to chatter against the stationary contacts.
   Solution: Ensure voltage and current match the equipment requirements per the user manual.
2. Motor humming noise:
   Causes:
   (1) Low voltage/current or phase mismatch causing motor reversal.
   Solution: Increase current and ensure correct voltage.
   (2) Overloading exceeding the rated capacity, causing an underpowered motor straining (“small horse pulling a big cart”).
   Solution: Reduce the load to below the rated capacity specified in the user manual.
   (3) Damaged motor bearings causing stator-rotor rubbing (commonly called “sweeping”).
   Solution: Repair or replace the motor.