MERITOR-TP-9853
MERITOR WEDGE BRAKES
MAINTENANCE MANUAL NO. 4R
FEBRUARY 1995
MERITOR-TP-9853 - Page 10 of 32
Section 1
Introduction
6
Automatic Adjustment
(RSA, RDA)
Correct lining to drum clearance is maintained
by the built-in automatic adjustment mechanism.
The mechanism includes the adjusting bolt, actuator,
adjusting plunger and the pawl assembly.
The mechanism is assembled as follows: The
adjusting bolt is threaded into the actuator.
The actuator slides freely inside the plunger.
The plunger slides freely inside the housing.
The pawl assembly is threaded into the side of
the housing, and the pawl fits through a slot in the
plunger. The pawl teeth engage the actuator teeth.
Figure 1.8
. Note that the teeth are shaped to slide
past each other only when the actuator is moving
outward.
Figure 1.9.
Each time the brake is applied, the adjusting
plunger, actuator and adjusting bolt move
outward. This movement of the actuator forces the
pawl against its spring, and the teeth begin to
disengage.
Figure 1.10.
As long as the lining to
drum clearance is within specification, the
actuator will not move far enough to completely
disengage the teeth. When the brake is released,
the teeth re-engage again.
Eventually, the lining wears enough that applying
the brake moves the actuator so far that the teeth
disengage and move past each other. After
they pass, the pawl spring forces the teeth to
re-engage.
Figure 1.11.
Figure 1.8
Figure 1.9
WEDGE
ASSEMBLY
ANCHOR
PLUNGER
PLUNGER
GUIDE
PAWL
ASSEMBLY
ACTUATOR
ADJUSTING
BOLT
ADJUSTING
PLUNGER
OUTWARD
MOVEMENT
ADJUSTING
PAWL
ASSEMBLY
Figure 1.10
Figure 1.11
TEETH
ENGAGED
TEETH
DISENGAGED
TEETH
RE-ENGAGED
Exaggerated for
illustrative purposes.
Back to Top
