EXTERNAL CONTRACTING BREAK
External contracting brakes are sometimes used for parking brakes on motor vehicles, for cranes, and for controlling the speed of auxiliary equipment drive shafts.
In operation, the brake band (or shoe) of an external contracting brake is tightened around the rotating drum by moving the brake lever. The brake band is made of comparatively thin, flexible steel, shaped to fit the drum,with a frictional lining riveted to the inner surface (fig.3-38). his flexible band cannot withstand the high pressure required to produce the friction needed to stop a heavily loaded or fast-moving vehicle, but it works well as a parking brake or hold brake.
Figure 1 shows an external contracting brake.The brake band is anchored opposite the point where the pressure is applied. In addition to supporting the band,the anchor allows adjustment of the brake lining clearance. Other adjusting screws and bolts are provided at the ends of the band.
