TM-9-2520-234-35
POWER TRAIN ASSEMBLY; ALLISON MODEL XTG411-2A
TECHNICAL MANUAL; FIELD AND DEPOT MAINTENANCE MANUAL
JULY 1962
TM-9-2520-234-35 - Page 46 of 323
CHAP 2, SEC II
DESCRIPTION AND OPERATION OF
PAR 17-18
MAIN TRANSMISSION ASSEMBLY
17. RIGHT AND LEFT BRAKES AND
APPLY CAMS
a. Components (figs. 377 and 378,
—
fold-outs 6 and 7)
(1) Right and left brakes an d
apply components are identical except
that certain items must be made to right
or left configuration. This is true of com-
ponents such as cam rings. Operation of
brake components is identical for both
right and left sides.
Because of the close
similarity of one side to the other, only
the left side components are described.
(2) The brake and apply compo-
nents include cam stationary ring 28 (fig.
378, fold-out 7), twelve steel balls 27, cam
rotating ring 19, hub 15, anchor ring 74
(fig. 377, fold-out 6), nine pins 78, nine
springs 77, ten plates 17 (fig. 378, fold-out
7) and ten disks 18. Cam stationary ring
29 is mounted on the transmission rear
housing by dowels and bolts 30, Cam ro-
tating ring 19 is installed on stationary
ring 28 after balls 27 are positioned in
inclined pockets of the stationary cam.
Matching inclined pockets in the rotating
cam also index with the balls. The cavity
between the cams is sealed by ring seals
26 and 32.
(3) Hub 15 is supported at one
end by ball bearing 16 and splined, at the
opposite end, to the steer planetary car-
rier 2. Brake disks 18 have internal splines
which engage external splines on the hub.
Brake plates 17 have external splines
which engage internal splines in anchor
ring 74 (fig. 377,
fold-out 6) which is
stationary.
Pins 78 and springs 77 are
installed in holes in anchor ring 74 and
retained by retaining rings 73. Reaction
plate assembly 66 serves the brake and
geared steer clutch jointly.
b . Operation (figs. 377 and 378,
fold-outs 6 and 7)
(1) The brakes are used for two
purposes. When applied simultaneously by
the mechanical linkage, they serve as ve-
hicle service and parking brakes. When
the vehicle is steered in first, second and
reverse 1 gears, the brakes apply indepen-
dently and hydraulically.
(2) When applied mechanically,
the brake linkage rotates cam ring 19 (fig.
378, fold-out 7) on cam stationary ring
28. The inclined ball pockets in the cams
roll on balls 27, causing the rotating cam
to move away from the stationary cam
and toward brake plates 17 and disks 18.
After running clearance is taken up, the
plates are compressed against reaction
plate assembly 66 (fig. 377, fold-out 6).
This locks hub 15 (fig. 378, fold-out 7) to
anchor ring 74 (fig. 377, fold-out 6) and
slows or stops the rotation of the geared
steer planetary carrier 2 (fig. 378, fold-
out 7). Thus the transmission output is
slowed or stopped.
(3) During steer (in first, second
and reverse 1), hydraulic pressure is di-
rected to the cavity between cam rings 19
and 28. This pressure applies the brake.
Note that, during steer, cam ring 19 moves
away from cam ring 28 without rotation.
18. BRAKE LINKAGE AND AIR VALVES
a. Components (fig. 379, fold-out 8)
—
(1) The linkage components by
which the service and parking bakes are
applied include spindle assembly 77, cage
assembly 72, right-brake apply shaft 97,
left-brake apply shaft 84, right-brake
apply cam assembly 83, left-brake apply
cam assembly 75, shafts 2 and 65, cam
followers 6 and 62, cam follower links 3
and 60, link assemblies 10 and 69, adjust-
ing nuts 20 (fig. 378, fold-out 7) and 14
(fig. 380, fold-out 9), ratchets 21 (fig.
378, fold-out 7) and 15 (fig. 380, fold-out
9), springs 22 (fig. 378, fold-out 7) and 16
(fig. 380, fold-out 9) and retainer assem-
bly 87 (fig. 379, fold-out 8).
(2) Retainer assembly 87, spindle
assembly 77 and cage assembly 72 support
brake apply shafts 84 and 97 in the trans-
mission rear housing. Brake apply cam
assemblies 75 and 83 are splined to their
respective brake apply shafts. Cam fol-
lower links 3 and 60 are pivoted at their
upper ends on shafts 2 and 65, installed in
the transmission rear housing. Link assem-
blies 10 and 69 connect to the lower ends
of the cam follower links. The cam fol-
lowers 6 and 62 rotate in the cam follower
links. The threaded ends of link assem-
18 Change 2
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