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Assembly
The work area must be clean! Handle all parts
carefully to avoid damage to polished sealing sur-
faces.
1. Check piston housing (5, Figure 5-7) bore for
nicks, scratches or dirt particles. Position housing
on work surface with bore facing up.
2. Lubricate square section O-ring portion of piston
seal assemblies (6 & 7) with type C-4 hydraulic
oil and install in piston (4) grooves. Be certain
O-ring is not twisted.
3. Lubricate piston groove and outer piston seal
rings. Install in grooves over O-rings, using fin-
gers or a smooth rounded object to push seal into
groove.
4. Install two equally spaced 1/2 UNC x 5.0 in. guide
studs in the housing at the piston retract spring
mount tapped holes.
5. Lubricate housing bore. Install lift eyes and attach
an overhead hoist to piston. Position piston over
housing with retract spring cavity holes aligned
with studs installed in previous step. Place a
spring guide over each stud to aid alignment.
Carefully lower straight into bore until seated
against housing. If necessary, seat piston by
tapping with a soft mallet.
6. Assemble twelve capscrews (1), spring guides (2)
and retract springs (3). Apply Loctite
screw threads and install assembled parts
through piston into tapped holes in housing.
Tighten capscrews to 90 ft. lbs. (122 N.m) torque.
Piston Pressure Test:
7. Test piston/housing assembly as follows:
a. Install a plug in one brake apply pressure port
(2, Figure 5-8).
b. Install a fitting into remaining port and attach a
hydraulic pressure test device.
c. Slowly apply pressure and loosen the apply
port plug to bleed air from piston cavity.
d. Cycle piston to full stroke ten times by applying
300 psi (2070 kPa) hydraulic pressure. Ob-
serve piston for leakage.
NOTE: Minor oil seepage (non-measurable) is permis-
sible. If leakage is greater, disassemble piston assem-
bly and determine cause.
J5-8
8. After completion of piston leakage test, release
pressure, remove hydraulic source and drain oil
from piston apply cavity. Plug ports to prevent
contamination.
9. Install O-ring (4, Figure 5-6) in groove of ring gear
(5).
10. Attach lifting eyes to piston/housing assembly and
lower into position over ring gear. Install cap-
screws (2) and hardened washers (3). Alternately
tighten capscrews to 575 ft. lbs. (780 N.m) torque.
11. Insert inner gear (5, Figure 5-9) into assembly.
Orient gear as shown.
12. Place shipping (retainer) bars over piston housing
as shown in Figure 5-9. Attach bars using 1/2 UNC
x 1.75 in. capscrews and lockwashers (7) at outer
ends of bars (4). Insert spacers (9) and 1/2 UNC
x 8.0 in. capscrews and lockwashers (8) as shown
to retain inner gear in position.
13. Attach lift eyes to assembly, lift and rotate to place
piston housing on the bottom.
14. Install discs as follows:
a. Insert a damper disc (1, Figure 5-10) into the
ring gear and inner gear with the friction mate-
rial (down) facing the piston (5).
b. Insert a friction disc (2) on top of the damper.
c. Install a separator plate (3).
d. Continue installing the remaining friction discs
and separator discs, alternating each type as
installed.
®
to cap-
NOTE: The disc pack contains a total of ten (10) friction
discs, nine (9) separator plates, and two (2) damper
discs.
e. Install the remaining damper on top of the last
friction disc with its facing material on top.
(Unfaced side toward top friction disc.)
15. Using a new O-ring (6, Figure 5-5), install back
plate (3) over ring gear. Be certain back plate is
oriented properly according to the match marks
made during disassembly.
NOTE: A seal carrier socket head capscrew hole on
the back plate should be aligned with the drain plug on
the piston housing.
16. Install capscrews (4) and hardened washers (5).
Alternately tighten capscrews to 575 ft. lbs. (780
N.m) torque.
Disc Brake Assembly
J05018 03/01
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