Service Manual

Section IV
4-SPEED
DESCRIPTION
The 4-speed unidrive transmission is an all-gear
transmission utilizing sliding gears and splined shafts
for easy shifting. All shafts operate on needle or ball
bearings supported by the transmission case.
The
transmission case consists of R.H. and L.H. cast iron
case halves which are dowelled for alignment and
bolted securely together.
RATIOS
1st gear ................
66.8 to 1
2nd gear ...............
42.4 to 1
3rd gear ...............
24.6 to 1
Reverse ................
51.5 to 1
REMOVAL AND REPLACEMENT
Removal:
These basic instructions apply to all tractors equip-
ped with Unidrive transmissions. Deviate from them as
necessary for any particular tractor.
Remove mid-mounted or trailing attachments, or
hitches which might interfere with transmission re-
moval. Support the tractor frame ahead of the trans-
mission just enough that the rear wheels no longer
carry any weight.
Remove the R.H. foot rest,
if so equipped, belt
guard, and belt. Disconnect the brake rod or remove
the brake band from the anchor bracket. On most
models, remove the fender and seat assembly.
If
necessary to gain clearance, remove the dust cover
and instruction plate located just ahead of the shift
lever.
Remove two cap screws that fasten through the
bottom of the tool box into the top of the transmis-
sion. Remove four cap screws that go through the
frame butt plate into the front of
the transmission.
Lower
the front of the transmission, guide the shift
lever down between the frame rails, and roll the
transmission and wheel assembly free of the tractor.
Drain lubricant, remove wheels, and clean trans-
mission as necessary before disassembling.
Installation:
NOTE: It is recommended that two pilot studs be
used to facilitate transmission installation. To make
the studs, cut
the heads off of two 3/8"-16 x 2" hex
head or carriage bolts. Grind a taper on the un-
threaded end of each bolt. Screw one stud into one
of the upper holes in the front of the transmission
case. Put the other one in
the diagonally opposite
lower hole.
Install input pulley, axle hubs and wheels. Move
the transmission assembly into place and guide the
shift lever up between the frame rails. Align the pilot
studs with the corresponding holes in the frame butt
plate and push
the transmission firmly in place against
the plate. Install cap screws in
the top of the trans-
mission and the open holes in
the front, and tighten
them until snug. Remove the pilot studs one at a time,
replacing them with cap screws. Tighten all six cap
screws securely.
UNIDRIVE
Connect brake linkage. Install dust cover, instruc-
tion plate, fender and seat assembly, drive belt, belt
guard, foot rest, etc.
Fill the transmission to proper level with S.A.E. 140
A.P.I. Service GL-5 gear oil. Remove support from
beneath tractor frame. Test tractor operation.
4-SPEED
UNIDRIVE TRANSMISSION
Disassembly:
These, instructions apply to all unidrive models un-
less indicated. A section applying only to specific
models will be so identified.
1. Remove axle hubs and input pulley.
2. Place the transmission assembly in a vise or
suitable holding fixture, as shown in Figure
1.
3.
4.
5.
6.
7.
8.
- 37 -
FIGURE 1
Place the gear shift lever in neutral and pull the
gear
shift lever rubber boot away from the trans-
mission boss. Loosen the gear shift lever retaining
lock nut and set screw and remove the gear shift
lever.
Remove the two
(2) brake band retaining bolts
and remove the brake band.
Remove the brake drum retaining bolt and wash-
er, and remove the brake drum. (See Figure
2).
Remove the six (6) 3/8” x 16 bolts and nuts that
retain
the right hand and left hand cases.
Remove paint and burrs from both axle shafts,
brake shaft, and the input shaft.
Remove the left hand case, as shown in Figure
3.