Abstract
A study has been made of the fluidborne vibration (noise) generated by a closed circuit hydrostatic power transmission consisting of a swash plate type axial piston pump, a motor and a connecting pipe. First the mathematical models for flow ripples and source impedances of the test pump and motor have been derived on the basis of the results in the authors' previous studies, and their appropriateness and applicable limits have been examined by making a comparison with the measured pressure ripples carried out on the"high impedance pipe method". Next, the mathematical model for pressure ripple in a hydrostatic transmission has been developed on the basis of the above four characteristic values and the known wave propagation theory for the fluid (oil) column in a connecting pipe. Experimental values of pressure ripple almost agree, up to harmonic frequencies of some 2500Hz. with predicted values from the proposed mathematical model, regardless of the values of system parameters such as working pressure, pump speed, pipe length, etc.
