System for obtaining read/write head (26) positioning movement and control for a storage disc drive. The rotational energy source for the disc (10) is also utilized for the additional task of indexing the read/ write head assembly (26, 28). To provide a simple, low-cost and reliable means of controlling the position of head assembly (26, 28), a belt (18), driven by the disc drive, drives rollers (50, 52) in opposite directions, and solenoid actuating means (68, 70) are employed to engage one of rollers (50, 52) with a track position wheel (80) to cause said wheel (80) to rotate in one of two opposite directions. The rotational movement is converted (44, 46, 47, 49) into indexing movement of the read/write head assembly (26, 28).