Automatic Brake Adjuster - Yale A7S1 Service Manual

8000 YRM 2199
adjuster to generate a larger force used to operate the
wheel cylinder to push the secondary Brake shoes,
and to force the upper end of secondary Brake shoes
to bear down on the support pin, thus to get a
relatively large brake force. In another connection, the
reversing brake action is performed in reverse
direction, but the brake force is the same as that
during forward movement.
1. BRAKE DIRECTION
2. POSITIONING PIN
3. FORCE
4. DRIVING BRAKE SHOE
Figure 27. Brake Actions during Forward Running
Process
1. POSITIONING PIN
2. BRAKE DIRECTION
3. FORCE
4. DRIVING BRAKE SHOE
Figure 28. Brake Actions during Reversing

AUTOMATIC BRAKE ADJUSTER

The automatic brake adjuster is able to automatically
maintain the clearance between brake shoes and
brake drum between 0.4-0.45 mm (0.016-0.018 in.) for
2-2.5 ton or 0.25-0.4 mm (0.01-0.016 in.) for 3-3.5 ton.
However this adjuster only acts during reversing
brake. During reverse movement, the brake shoes will
disengage once the brake pedal is activated, thereby,
the secondary and the primarily Brake shoes will begin
to get into contact with brake drum for rotation
together, until the upper end of primarily Brake shoes
begins to get into contact with support pin.
When the secondary brake shoes is released from the
support pin, the A part of adjusting level Figure 25).
When the brake pedal is released, point B of the rod is
lowered. As the clearance between the friction plate
and the brake drum is increased, the distance of point
B increases also. When the distance is more than
0.4mm, point B will contact the adjuster bolt (item 38,
Figure 25) and the clearance will decrease.
Brake System
Process
31