Many designers have long accepted leaks as inherent to hydraulic systems, even though advances in technology should have eliminated hydraulic leakage a long time ago. Hydraulics suffers a similar identity crisis when it comes to noise. Noise certainly cannot be eliminated, but a number of products and techniques exist to at least bring noise down to an acceptable level.
Sources of noise
A hydraulic system’s greatest contributor to noise is the power unit, Figure 1. Noise not only emanates directly from the electric motor and pump, but also is caused by pressure fluctuations in the hydraulic fluid and by components. This results from these pressure fluctuations or from physical vibration.
Electric motor noise comes from bearings, the rotor and stator assembly (the characteristic hum), and, especially, the fan. A standard electric motor contains a fan with blades designed to provide cooling whether the motor shaft rotates clockwise or counter-clockwise.
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Read more: Noise control in hydraulic systems