Precision clutches utilize a full complement of sprags which are placed between concentric inner and outer races. A light spring ensures that the sprags are always in contact with the races. Torque is transmitted from one race to the other by wedging action of the sprags between the races. The sprags hae greater dimension (B) across one set of diametrically opposite corners than across the other (A) as shown in Figure 1, Precision clutches provide instantaneous engagement or disengagement without backlash.

FIGURE 1Shows the sprags in a position to allow the inner race to overrun counter-clockwise or the outer race to Overrun in a clockwise direction.

FIGURE 2 The inner race has rotated clockwise and has forced the sprags to ratate counter clockwise partially loading the cluth.

FIGURE 3 The sprags are fully loaded and loads can be transmitted through the sprags from a clockwise rotation of the outer race.