What causes abnormal noises inside hydraulic cylinders?
First, it may be due to air mixing into the hydraulic oil. Air forms bubbles in the oil, and when the cylinder operates, the bubbles burst, producing a "crackling" sound, much like ripples forming when a stone is thrown into calm water.
Second, part wear is one of the common causes. For example, excessive wear between the piston and cylinder barrel or between the piston rod and guide sleeve can lead to increased clearance, resulting in harsh friction noises, similar to the "creaking" sound of an old wooden door opening and closing.
Third, loose fasteners inside the cylinder can also cause abnormal noises. When fasteners fail to securely hold the components in place, collisions and vibrations between parts can produce unusual sounds, akin to loose parts rattling inside a shaking box.
Fourth, inappropriate hydraulic oil viscosity may also be the "culprit." If the oil viscosity is too high or too low, it can affect its flow properties, causing the cylinder to emit abnormal sounds during operation.

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