TM 5-3895-359-14&P
TWO SPEED NOSE BOX TRANSMISSION
Refer to Drive Unit cleaning instructions on page 5-12.
GENERAL
INSPECTION
The two speed nose box transmission is attached to the
It is impossible to overstress the importance of careful
front of the traction drive axle. It provides a gear
and thorough inspection of drive unit parts prior to
reduction of 5.938:1 in the low range. In the high range
reassembly. Thorough visual inspection for indications
the ratio is 1:1 with the transmission of power being
of wear or stress, and the replacement of such parts as
direct from the hydrostatic motor to the traction drive
are necessary will climinate costly and avoidable drive
axle.
unit failure.
A. Inspect all bearings, cups and cones,
DISASSEMBLY
including those not removed from parts of
1. Drain oil - position with input up.
the drive unit and replace if rollers or cups
2. Remove transmission dowels and capscrews.
are pitted or damaged in any way.
Remove parts needing replacement with a
3. Remove shift shaft (17) detent plug.
suitable puller or in a press with sleeves.
4. Remove transmission cover (33).
Avoid the use of drifts and hammers.
They may easily mutilate or distort
NOTE: Assembled position of clutch shift collar; the
component parts.
tapered portion of collar is toward low speed driven
gear.
B. Inspect shift shaft, shift fork, shift clutch
collar, and clutch pinion. Replace if clutch
5. Remove idler gear assembly (7), (8), (9).
engagement teeth are worn, chipped or
6. Remove shift shaft (17) and fork assembly (19)
mutilated.
with clutch shift collar (36).
C. Inspect spur gears for wear or damage.
Gears which are pitted, galled or worn or
NOTE: Clutch shift collar may have lockup type
broken through case hardening should be
feature which may require alignment of clutch teeth
replaced. Inspect bushings for wear or
to remove.
scoring.
7. Remove three each clutch detent balls (39) and
D. Inspect clutch engagement teeth of input
springs (38) from clutch pinion (37).
drive pinion and low speed spur gear.
8. To remove low speed driven gear (42) or clutch
Replace if worn, chipped or mutilated.
pinion (37), locate and remove set screw (40)
E. Inspect internal spline of input drive pinion
from clutch
for wear or damage.
pinion (37).
9. Remove clutch drive pinion retaining nut (35)
REPAIR
(1-7/8" socket required).
A. Replace all worn or damaged parts. Hex
10. Remove clutch drive pinion (37).
nuts with rounded corners, all lock
11. Remove low speed driven gear (42), this allows
washers, oil seals and gaskets should be
access to the bevel pinion bearing oil seal (43),
replaced at the time of overhaul.
and transmission case to differential carrier
Use only genuine Rockwell-Standard
capscrews (44).
parts for satisfactory service.
For
12. Disassemble input drive pinion (34) and motor
example, using gaskets of foreign
adapter (28).
material generally leads to mechanical
A. Remove
input
motor
adapter
to
trouble due to variations in thickness and
transmission cover stud nuts (29).
the inability of certain materials to
withstand compression, oil, etc.
B. Unlock locking tab (24) at input drive
pinion bearing adjusting nut (23).
B. Remove nicks, mars and burrs from
machined or ground surfaces. Threads
C. Remove input drive pinion nut (23), nut
must be clean and free to obtain accurate
lock (24) and washer (25).
adjustment and correct torque. A fine mill
D. Remove input drive pinion (34), keep
file or India stone is suitable for this
bearing cups and cones paired.
purpose. Studs must be tight prior to
13. To remove bevel pinion or transmission case,
reassembling the parts.
will require disassembly of differential carrier.
C. When assembling component parts use a
press
where
necessary.
Avoid
Refer to Drive Unit disassembly instructions on page 5-
hammering.
1.
D. Tighten all nuts to specified torque. See
CLEANING
torque limits following service instructions.
5-8
