FIELD: hydraulics. SUBSTANCE: in mode of braked hydraulic motor, valves 19, 20 and 21 are closed. When signal is fed from control unit, pressure in lines 6 and 7 is changed. Signals from pressure pickups 13 and 14 are furnished to pressure differential computing unit 15 and difference of these signals is fed to input of graph plotter 18 through selector switch 17 placed in "P" position. As a result, power characteristic of electrohydraulic amplifier is recorded. Simultaneously, signals from pickups 13 and 14 are furnished to input of discriminator 16 at whose output pulse of short duration and small amplitude is shaped at zero drop; this pulse is imposed on main signal and characteristic is clamped to position of hydraulic neutral of amplifier. To measure speed characteristic, valves 19, 20 and 21 are opened and tachogenerator 11 feeds signal corresponding to flow rate to graph plotter 18. Selector switch 17 is in "O" position. Gears 23, 24, 25 and 26 maintain constantly kinematic linkage of hydraulic motor with flow meter 11 in field of low flow rates. EFFECT: enhanced efficiency. 2 cl, 3 dwg
