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External Contracting Break

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.

 

Fig. 1 External Contracting Break

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.

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