Effect of a Pulse Damper on a Hydraulic System on Operator Ear Noise

The basic theory of an expansion chamber assumes an infinite straight outlet tube and no reflected waves; neither of these conditions exist in practice since a vehicle's hydraulic system contains a finite length of tubing with bends, constrictions, and valves. These complicating factors make the reduction of fluidborne noise a system design problem rather than only a component design problem. Despite these problems and packaging problems which prevented the optimization of the filter design, very significant operator ear noise reduction was achieved by addition of the expansion chamber in the hydraulic system of a certain prototype tractor with cab.