F04B 49/123

Control {, e.g. of pump delivery, or pump pressure} of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups [CPC: F04B1/00] - [CPC: F04B47/00] by varying the length of stroke of the working members {by changing the eccentricity of one element relative to another element}