This part of ISO 4392 specifies two test methods for determining the startability of rotary hydraulic motors. It describes two comparable methods of measurement, namely the constant torque method (see clause 6) and the constant pressure method (see clause 7). Since the results obtained by these two methods are equivalent, no preference is given to either. Additional physical quantities and their symbols are given in annex A. The accuracy of measurement is divided into three classes, A, B and C, which are explained in annex B.