chapter  31
Noise Reduction
Pages 18

The noise in fluid power machinery-both hydraulic and pneumatic-can be substantially reduced by application of known design principles.

In hydraulic equipment (a harvesting machine is an example to be covered), the noise originates primarily in the pulsations of reciprocating power elements, such as pistons, which rapidly pressurize and exhaust the hydraulic fluid. Secondary sources of noise include throttling, turbulence, cavitation, and chattering in pumps, motors, and valves . Bubbles of entrained air and even vaporized water create noise when they colLapse violently.