CAM TO EXPAND BRAKE SHOES
Figure 2-22.--Internal expanding brake.
Brake shoe and lining
5. Pin spring
9. Anchor pin lock
10. Front brake shoe return spring
Front brake shoe anchor plate assembly
Front brake shoe link pin lock
7. Pin lock
11. Front brake shoe wheel cylinder
8. Anchor pin
12. Front brake shoe link
Front brake shoe link pin
Figure 2-23.--Wheel brake assembled and exploded view.
Tw o s h o e s a r e u s u a l l y a r r a n g e d s o t h a t
the wheel is revolving in the opposite direction, the
self-energizing action is produced on the opposite
self-energizing action is effective on both, regardless
of the direction of drum rotation. This is accomplished
by pivoting the shoes to each other and leaving the
With the arrangement shown in figure 2-25, both
pivot free of the brake shield. The only physical effort
shoes are positioned to develop self-energizing action
required is for operating the first, or primary, shoe.
with forward movement of the vehicle. For this reason,
Both shoes then apply additional pressure to the
the arrangement is used mostly on the front wheels
braking surfaces with no increase in the pressure on the
where maximum braking effort is required during
operating linkage. The anchor pins are fitted into slots
n o r m a l f o r wa r d m ove m e n t . I n r eve r s e , t h i s
arrangement would not have any servo action.
in the free ends of the brake shoes.