This paper presents a new speed control method for a two-mass system coupled by a flexible shaft. Two control loops are proposed; the outer angular speed control loop calculates the reference signal for the inner loop, where the torsion of the shaft is handled as a variable under control. In this paper, the observer-based discrete-time sliding-mode (ODSM) control implementation and experimental verification of direct torsion control is presented. The experimental system consists of a conventional DC servo gear motor with encoder feedback and inertia load coupled by a flexible shaft. The controller was implemented using a transputer as the computation engine.