Caliper Check - Caliper Running Clearance; Caliper Check - Caliper Movement Along Guide Pins - PREVOST H3-41 Maintenance Manual

21. Check the brake disc.
22. Check caliper running clearance (see
18.2.7 & 18.2.8).
23. Fit the brake pads.
24. Fit the brake actuator.
25. Recheck the adjuster (see 18.2.6).
If the air gap is still smaller than 0.6 mm between
both tappets, the brake caliper must be replaced.
18.2.7 Caliper check
Clearance
The Knorr Bremse air disc brake is designed to
move freely, with minimal force.
1. Before starting work, ensure that the
wheels are chocked and the vehicle can-
not roll away.
2. Ensure that service brake and parking
brake are in the released condition.
3. By pushing and pulling the caliper in an
axial direction by hand (see arrows in Fig-
ure 38), a movement of 0.6 - 1.1 mm must
be possible.
If, even using a high level of hand pressure (no
tools), the caliper is not moveable, the caliper
guide pin seals must be further examined.
Figure 39: running clearance
18.2.8 Caliper check - Caliper Movement Along
Guide Pins
1. With the open bearing variant (6b), clean
the protruding area of the guide pin (4b)
from outside of the caliper and if neces-
sary remove any light corrosion using an
emery cloth.
- Caliper Running
PA1621 Maintenance Manual All Series | Revised June 2020
SECTION 12: BRAKE AND AIR SYSTEM
2. Lightly apply grease to the protruding area
of the guide pin (4b).
3. Remove brake pads.
4. Fully wind back the tappets (13) using a
ring spanner and shear adapter (61) (see
Figure 40).
FIGURE 40: REWIND TAPPETS COMPLETELY AND
PUSH CALIPER IN DIRECTION OF MIDDLE OF VIEW
5. Push caliper inboard towards vehicle's
center (see Figure 41).
FIGURE 41: FREE GUIDE PIN OF DIRT
6. With both open bearing variants (6a and
6b), clean guide pin (4a or 4b) from the
inner area of the caliper, removing any dirt
or corrosion.
7. Lightly apply grease to guide pin (4a or
4b).
8. Caliper (1) must slide freely along the
whole length of the guide pin arrange-
ment; movement should be greater than
0.984 in / 25 mm. (see Figure 42).
If the caliper does not move at least 0.984 in / 25
mm, the caliper guide pin seals must be
examined (see 18.2.10 & 18.2.11).
37