This paper proposes a scaling law for estimating the speed limitations for a family of axial-piston swash-plate type hydrostatic machines. The speed limitations for this machine are considered from three mechanical perspectives: (1) cylinder-block tipping, (2) cylinder-block filling, and (3) slipper-tipping. As shown in the results of this research, each speed limitation is scaled by the inverse of the cube root of the volumetric displacement for the new machine. In other words, small machines are shown to have a higher speed capacity than larger machines. By scaling a baseline machine using the scale laws that are presented here, a new machine may be produced that obeys a simple rule related only to the volumetric displacement of the new machine. Serendipitously, and perhaps most usefully, all three speed limitations obey the same rule! The speed limitations that are derived in this research are compared to existing industry data of currently scaled products and it is shown that the proposed scale laws correspond well with this data.

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