The Basic Theory of Hydraulic Dynamometers and Retarders

This paper presents an analysis of the theory of the hydraulic dynamometer, the specific objective being to derive an expression for the capacity constant K in the well-known equation T = KN²D⁵ in terms of the relevant parameters. The major conclusion is that K is fundamentally a function of only five factors, all of which are discussed fully. The interrelation among the various factors is explained in detail. Based on certain simplifications, an experimental technique is suggested, from which a rational design of dynamometers becomes possible.