Bendix Commercial Vehicle Systems ADB22X-V Air Disc Brakes - Manual (Page 15)

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in Figure 27. Press the caliper in the direction of
the carrier (2) and set the dial-gauge to zero.
4.5.3 Place a suitable tool (e.g. a large flat-blade
screwdriver) between carrier (2) and caliper (1) and
use light hand force to move the caliper away from
the carrier, until the movement stops. Read the
maximum value on the dial-gauge. See Figure 27.
If the value is greater than 0.039 in. (1.0 mm), replace
the guide pin bushings (See Section 5.6) OR replace the
caliper/carrier assembly (See Section 5.3).
Inspect the guide pin inner boots:
4.5.4 See Figures 28 and 29. With the pads removed,
slide the carrier by hand to the inboard position (See
Figure 28). By looking through the opening where
the pads are installed — and also from below —
inspect the inner boot (9) for each of the guide pins.
INSPECT FOR DAMAGE, CUTS AND CRACKS.
Replace damaged boots immediately to prevent
dirt and/or moisture affecting the movement of the
guide pins (See Section 5.4). Damaged or corroded
guide pins will impair the operation of the brake.
In addition, during installation, the boots are
compressed to minimize the amount of air trapped
within them. Observe as you move the carrier back
towards the outboard position; the boots should only
expand outwards a small amount due to trapped
air. The boots should normally (due to their ribbed
construction) contract back into place as the caliper
moves on the guide pins. The boots are not air-
tight and so some trapped air is normal; excess air
trapped will dissipate.
Inspect
Boot
FIGURE 28 - GUIDE PIN BOOT INSPECTION (THIS IMAGE DOES
NOT SHOW THE CARRIER)
4.5.5 Inspect the original pads (See Section 4.3) and they
may be reused if they are in good condition with
suffi cient pad thickness.
4.6 TAPPET AND BOOT ASSEMBLY
INSPECTION
4.6.1 In order to inspect the tappet and boot assembly,
remove the pads (12) (See Sections 4.3 or 5.2) and
advance the shear adapter (61) clockwise.
CAUTION: NEVER EXTEND THE TAPPET MORE THAN
1.75 in. (44.5 mm). See Figure 29. Over-extending the
tappet will result in the tappet losing engagement with
the synchronizing mechanism. Since the mechanism
can only be set at the manufacturing plant, the caliper/
carrier assembly must be replaced
if this happens.
4.6.2 INSPECT THE TAPPET AND BOOT ASSEMBLIES
(13) FOR EVIDENCE OF DAMAGE, CUTS,
C R A C K S , T E A R S A N D E V I D E N C E O F
CORROSION, ETC. Damaged boots lead to the
penetration of dirt and moisture, and can lead to
corrosion and impair the operation of the brake.
Replace as necessary (See Section 5.5).
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Extend LESS THAN
1.75 in. (44.5 mm.)
FIGURE 29 - PERMITTED TAPPET EXTENSION
Where the tappets and boots pass the inspection, retract
the tappets using the shear adapter.
When installed, the boots are compressed to minimize the
amount of air trapped within them. Observe as you move
the tappet back using the shear adapter; the boots should
only expand outwards a small amount due to trapped air.
The boots should normally (due to their ribbed construction)
contract back into place as the tappets move. Note: If the
bellows have excess air trapped, then with the tappets
retracted, remove and re-install the actuator to vent the
excess trapped air (See Section 5.4).
Follow the reinstallation steps for the brake pads (See
Section 5.2).