adjuster pushes the secondary shoe by the larger force than that offered by operation
of the operating cylinder. The secondary shoe upper end is forced strongly against the
anchor pin, providing large braking force. On the other hand, the braking operation in
the truck's reverse travel is performed in reverse order, but the braking force is the
same as that in the case of the truck's forward travel.
8.4 Clearance Self-adjuster
This section states mainly the clearance self-adjuster in the 2 ton truck's brake.
And the clearance self-adjusters in the remainder truck's brakes are the same as that in
the 2 ton truck's brake in operation principles.
The clearance self-adjuster keeps clearance between the friction piece and drum
within 0.4-0.45mm (0.25-0.4mm for the 3-3.8 ton trucks) by itself. This adjuster,
however, actuates only when the truck in reverse travel is braked. When the brake
pedal is pressed in the truck's reverse travel, the brake shoe are spread. As a result of
this, the secondary and primary shoes come into contact with the brake drum and
rotate together until the upper end of the primary shoe comes into contact with the
anchor pin.
As the secondary shoe leaves the anchor pin, the section (A) of the adjusting
lever (Refer to Fig.8-2) is relatively pulled. Therefore, the adjusting lever turns around
the section (B) so that the section (C) of the adjuster lever lowers, causing the section
(D) of the adjuster to turn left and the adjusting achieved. As the brake pedal is further
Brake drum's
rotation direction
Anchor pin
Force
Primary
shoe
Secendary
shoe
Force
Primary
shoe
Secendary
shoe
Fig.8-4 Braking operation in
the truck's forward travel
Fig.8-5 Braking operation in
the truck's backward travel
-57-
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