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Massey Ferguson 250 - Differential and bevel drive gear
Differential
Massey Ferguson 250 and Orchard model tractors are equipped with
planetary final drive units located in outer end of rear axle housings.
On all other models, the rear axle shaft splines directly into the
differential side gears. All models may be equipped with a mechanically
actuated jaw-type differential lock.
Remove, reinstall and overhaul - The ring gear and differential unit can
be removed from differential housing after removing the rear axle
housing assembly from left-hand side of Massey Ferguson 250 tractor.
Disassemble the removed differential unit, first scribe alignment marks
on both halves of differential case to ensure correct reassembly. Pull
bearing cone off differential lock coupler cap, then remove cap screws
retaining coupler cap. Remove coupler cam and separate differential case
halves. Differential side gears, pinion gears and cross can now be
removed. The main drive bevel ring gear is secured to differential case
half with either special bolts and nuts or rivets. Note that ring gear
is a press fit on case and may also be epoxy bonded to case if it has
been previously serviced. Inspect all parts for scoring, chipping, wear
or other damage and renew if necessary. Pinion gears and cross should be
renewed as a set. Backlash between pinion gears and side gears should be
0.08-0.28 mm (0.003-0.011 inch). Reassemble differential, reverse the
disassembly procedure while noting the following special instructions:
If bevel ring gear was removed, use special epoxy bonding kit when
reinstalling. Be sure to follow kit instructions and cure epoxy for
correct time at specified temperature. Apply Loctite 262 to threads of
ring gears retaining bolts and tighten evenly to 160 Nm (120 fl-lbs.)
torque. Be sure to align differential case scribe marks, and tighten
retaining cap screws to 108 Nm (80 ft.-lbs.) torque. To reinstall
differential, reverse the removal procedure. If differential case halves
and/or carrier bearings were renewed, bearing preload should be checked
and adjusted as outlined in paragraph 159.
Carrier bearing preload - The differential carrier bearing preload is
adjusted by installing correct thickness spacer shield, or shim
depending on differential type, under right-hand carrier bearing cup.
The recommended method of checking the preload adjustment is by use of
Massey Ferguson special tool. If tool is not available, an alternate
procedure (although not as accurate) can be used as follows: This
adjustment procedure should be performed with bevel drive pinion gear
removed to prevent interference with movement of differential. Install
differential assembly and left-hand axle housing, or carrier bearing
housing, depending on differential type. Install a 1.27 mm (0.050 inch)
spacer shield, or several shims, and bearing cup into right-hand axle
housing or carrier housing. A spacer shield thickness change is likely
using this procedure. When shield is removed it Is usually distorted
beyond reuse. Position axle housing or carrier housing (without gasket
or O-ring) onto differential housing and install three or four equally
spaced retaining cap screws. Tighten cap screws evenly until end play of
differential is just removed. Rotate differential several turns to make
certain that bearings are properly seated. Use a feeler gage to measure
gap between axle housing and differential housing at several different
locations. Preload will be correct when measured gap is 0.43-0.55 mm
(0.017-0.022 inch) on models with drum brake axles, or 0.25-0.38 mm
(0.010-0.015 inch) on models with disc brake axles. Remove axle housing
or carrier housing and change spacer or shim thickness as necessary.
Differential lock
Operation - When the differential lock foot pedal is depressed, the axle
half of coupler is forced inward to contact the differential case half
of the coupler. If slippage is occurring at one wheel, depressing the
pedal will cause the coupler dogs to lock the differential case to the
right axle. The differential and both drive wheels then rotate together
as a unit. As soon as contact is made by the coupler dogs, the pressure
wlll keep the differential lock engaged and foot pedal may be released.
When ground traction on both drive wheels again becomes equal, coupler
dog contact pressure will be relieved and the coupler will automatically
disengage.
Adjustment - On all except Orchard models and MF 250 models,
differential lock coupler should be fully engaged when pedal clears
tractor step plate by 12 mm (1/2 inch). If adjustment is required,
loosen clamp screw and reposition pedal on actuating shaft. Retighten
clamp screw when adjustment is complete. On Orchard models and MF 250
models, pedal should be against stop when released. If not against stop,
loosen locknut and turn clevis until pedal arm just contacts stop.
Tighten locknut after acljustment is complete.
Remove and reinstall - Remove the differential lock coupler halves,
first drain Massey Ferguson 250 transmission and hydraulic reservoir,
block up under diffet·ential housing and remove right fender and rear
tire and wheel assembly. Remove right lower hitch link and disconnect
right brake linkage. Support rear axle housing assembly in a hoist and
remove retaining stud nuts, then slide right rear axle and housing as a
unit away from differential housing. Remove bearing cone from coupling
half. Remove the differential case retaining cap screws and lift off the
coupling. When installing, tighten differential case cap screws to a
torque of 108 Nm (80 ft.-lbs.). To remove axle half of coupler on models
without planetary final drive, upbolt rear axle outer bearing retainer
from axle housing and withdraw axle from housing; then lift out the
coupler. Shoes will be free in fork with coupler removed. To service the
actuating mechanism, remove the clamp bolt and withdraw actuating shaft
from housing and pedal, then lift out the remaining actuating parts.
Remove axle half of coupler on models with planetary final drive, remove
spring pin securing shift fork to actuating shaft and the two
countersunk screws secw·ing carrier plate to axle housing, then slide
plate, fork and coupler carefully off end of drive axle. On all models,
assemble by reversing the disassembly procedure and adjust after axle
housing is reinstalled.
Main drive bevel gears
Remove and reinstall - The main drive bevel ring gear and bevel pinion
gear must be renewed as a matched set. Remove bevel ring gear, first
remove differential assembly. Ring gear retaining nuts are installed
with thread locking compound, and removal will be easier using a slight
amount.of heat on the nuts. Ring gear is a tight fit and may also be
bonded to differential case with epoxy, so it will probably be necessary
to press ring gear from differential case. Remove bevel pinion gear,
first remove hydraulic lift cover. Remove axle housings and differential
assembly if not previously removed. On Massey Ferguson 250 tractor
equipped with independent pto, Multi-Power transmission or auxiliary
hydraulics, split the tractor between differential housing and
transmission housing. Remove pto side cover, disconnect hydraulic lines,
remove pump support pins and remove hydraulic pump assembly and
independent pto clutch unit out front of differential housing. On MF 250
models not equipped with independent pto, Multi-Power transmission or
auxiliary hydraulics, it is not necessary to split the tractor to remove
pinion shaft. Remove the coupler tube and pinion drive shaft. Remove
side cover from left-hand side of housing and move pto driven gear
forward on pto shaft splines. Remove ground speed pto drive gear from
pinion shaft. On all models, remove cap screws attaching retainer to
housing, then thread two of the cap screws into the tapped holes in
retainer. Tighten the two cap screws evenly to force retainer with
pinion as an assembly from housing bore. Check and adjust differential
carrier bearing preload, If necessary, before reinstalling bevel pinion
gear. When reinstalling bevel pinion gear, make certain that the
locating pin is aligned before pressing retainer into place. Tighten
retainer cap screws to 108 Nm (80 ft.-Ibs.) torque. Complete
installation by reversing the removal procedure.
Overhaul - Disassemble bevel pinion gear, proceed as follows: If bearing
adjusting nut is retained by a tab washer, unlock tabs and remove the
nut. If bearing adjusting nut is retained by locking pins, it will be
necessary to split the nut using a hammer and chisel to remove nut from
the shaft. Be careful to avoid damaging threads of pinion when splitting
the nut. On all models, bump the pinion shaft out of retainer after nut
is removed. Examine all parts for wear or other damage and renew as
necessary. Bearings and retainer are serviced as an assembly. When
reassembling pinion gear, tighten nut to obtain pinion rolling torque of
2.25 Nm (20 in.-lbs.) to provide correct bearing preload. Secure nut by
bending tabs of lock washer or by driving locking pins down both sides
of one of the pinion splines. Be sure pins are flush with end of
adjusting nut. When installing the ring gear, make certain that mating
surfaces of ring gear and differential case are thoroughly clean and
free from nicks or burrs. Apply special epoxy to both mating surfaces
and cure for specified time following kit instructions. Apply Loctite
262 to threads of retaining nuts and tighten to 108 Nm (80 ft.-lbs.)
torque.
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