In the past if there was a noise specification to be met, the hydraulic circuit designer selected a pump, from a manufacturer's catalog, that showed a low decibel rating. However as the power unit was manufactured the noise level usually turned out to be higher than that shown in the pump catalog. The problem is that any slight noise generated by the pump is amplified throughout the hydraulic circuit. This pager deals with a new method of stopping the noise before it can be amplified.
