Komatsu 930E-2, Shop Manual

Page: 355 / 739

Cleaning and Inspection
If the brake wear indicator test indicates internal
brake components are worn to the maximum al-
lowable limit, it is recommended that all friction
discs, separator plates and dampers should be
replaced with new parts. Always replace seal as-
semblies and O-rings with new parts.
1. Clean all parts thoroughly prior to inspection.
2. Remove and discard toric rings from floating ring
oil seal assembly (6, Figure 5-1) in seal retainer
and back plate. Inspect seal ring polished (mat-
ing) surfaces for scratches or other damage. In-
spect the contact band of the mating faces to
determine amount of wear.
NOTE: A new seal will have a contact band (dimension
“A”, Figure 5-8) approximately 0.06 in. (1.6 mm) wide.
As wear occurs, the contact band will widen slightly
(dimension “B”) and migrate inward until the inside
diameter is reached and the entire seal assembly must
be replaced. Remaining seal life can be estimated by
the width of the contact band.
3. Inspect piston housing for nicks or scratches in
piston seal area. If nicks or scratches cannot be
removed by polishing, replace housing.
4. Inspect piston seal assembly grooves for damage.
5. Inspect piston retract springs (3, Figure 5-7).
Check springs for free height and test for height
under load. Replace if not within approximately
10% of specification.
Free Height:
. . . . . . . . . . . 4.00 in. (101.6 mm)
Height @ 225 lb. (1000N) working load:
. . . . . . . . . . . 3.351 in. (85.12 mm)
Height @ 600 lb. (2669N) working load:
. . . . . . . . . . . 2.750 in. (69.9 mm)
6. Inspect friction disks for warping, tooth wear, and
excessive friction material wear. Replace if wear
exceeds minimum groove depth.
Disc thickness including friction
material: . . . 0.30
±
0.01 in. (7.7
±
0.3 mm
)
Friction material thickness (new)
. . . . . . . . . . . . . 0.04 in. (1.1 mm)
Nominal friction material groove depth:
. . . . . . . . . . . 0.025 in. (0.63 mm)
Minimum allowable friction material groove
depth: . . . . . . . . 0.010 in. (0.25 mm)
Flatness over friction material (new)
. . . . . . . . . . . . 0.018 in. (0.45 mm)
7. Inspect separator plates for warping and tooth
wear.
Disc thickness (new)
. . . . . 0.146
±
0.004 in. (3.7
±
0.1 mm)
Flatness (new)
. . . . . . . . . . . . 0.020 in. (0.5 mm)
8. Inspect damper plate for warping, tooth wear and
excessive facing material wear
Disc thickness, including facing material
(new)
. . . . . 0.323
±
0.020 in. (8.2
±
0.5 mm)
Disc thickness, steel plate only (new)
. . . . . 0.146
±
0.004 in. (3.7
±
0.1 mm)
Flatness, steel plate (new)
. . . . . . . . . . . . 0.020 in. (0.5 mm)
9. Inspect ring gear for excessive tooth wear and
nicks and scratches in O-ring seal grooves.
10. Inspect inner gear for excessive tooth wear and
damage at capscrew holes.
FIGURE 5-8. SEAL WEAR PROGRESSION
J05018 03/01 Disc Brake Assembly J5-7