Relay control systems are widely used in engineering. Simple construction, reliability and low cost are the main advantages of such systems. Relay control systems are used in industrial control systems and also in moving objects control systems. Real values of control system plant parameters almost always differ from design (nominal) values. /t also applies to relay self-oscillating control systems. Deviations of relay self-oscillating control system plant parameters may lead to perceptible reduction of input signals tracking accuracy, and in special case - to instability of periodic motions in the system. /t makes the system unusable. So it's very important to control parametrical sensitivity of system characteristics at the stage of relay self-oscillating system synthesis. With the participation of the authors of this article effective methods of research of nonlinear tracking relay self-oscillating systems parametrical sensitivity were developed. These methods allow to research parametrical sensitivity of the system periodic motions and the system tracking mode. /n this article the synthesis of the relay self-oscillating power volume hydraulic drive by setting limits on the sensitivity of its characteristics to changes of the pump drive motor rotation speed is considered using designed methods. Such hydraulic drives are often used in control systems of moving technical objects. The main drawbacks of volume hydraulic drives, which limits their application in tracking control systems, are difficulty of variable pump controlling and also significant dependence of drive characteristics on the rotation speed of the drive motor of the hydraulic pump. /ts instability adversely affects on accuracy characteristics and efficiency of the drive. As a result, the synthesis could provide high accuracy and efficiency of hydraulic drive.