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Case IH 885, 485 Tractor Synchromesh speed transmission
The synchromesh speed Case IH 385, 485, 585, 685, 885 tractor
transmission used on models, is located in the rear portion of the
clutch housing (speed gearbox).
On tractor models equipped with the two speed Power Shift or
Forward-Reverse transmission, speed transmission is directly behind
them.
The tractor speed transmission is equipped with synchronizers and
therefore can be shifted with the tractor in motion by disengaging the
clutch and applying a steady and continuous pressure to the speed shift
lever until the shift is complete. The speed gearbox must be removed for
all service on the speed transmission.
The Case 885, 485 four speed synchromesh transmission in conjunction
with range transmission and without the Power Shift or Forward-Reverse
transmissions, provides eight forward and four reverse speeds.
Overhaul
To remove the speed gearbox, first remove cab and fuel tanks or fenders,
tank, platform and tunnel cover. Remove drain plugs and drain fluid from
speed gearbox and rear frame. If so equipped, remove front drive axle
drive shaft and shield. Unbolt and remove pto clutch cover from bottom
of rear main frame.
Drive out roll pin (1) from pto clutch and shaft. Unbolt lower pto shaft cover or seal housing, as equipped, and remove with gasket from rear of tractor.
Have helper support the pto clutch. Withdraw lower pto shaft and remove
pto clutch. Remove snap ring from rear of pto driven gear, then remove
driven gear.
Disconnect all interfering hydraulic lines and electrical wiring. Then,
using a sling and hoist, lift, off steering support assembly. Disconnect
lst-2nd and 3rd-4th selector rods from gear selector levers. Remove
right and left brake pipes. Remove steering supply and return pipes and
oil cooler supply and return pipes.
Cap or plug all openings immediately to prevent foreign material from
entering systems. Place special tool or equivalent, under tractor.
Adjust splitting tool to support tractor under speed gearbox and rear
main frame.
Place wooden wedges between front axle and front support to prevent
tipping. Unbolt range section (rear frame) from speed gearbox. After
making certain that all wires and hydraulic lines are disconnected, roll
engine and speed gearbox forward from range section.
Attach a sling and hoist to speed gearbox and block up securely under
engine oil pan. Unbolt clutch housing from engine, then separate speed
gearbox from engine. If available, attach speed gearbox to a
transmission stand.
Fig.5. Case IH 885, 485 tractors Speed gearbox cover and
relative components
1.Expansion plugs, 2.Cover, 3."O" ring, 4.Brake return adaptor, 5."O"
ring, 6.Housing, 7.Interlock pivot, 8.Shift lever (1st-2nd), 9.Housing,
10."O" ring, 11.Lube hose, 12.Shift lever (3rd-4th), 13.Housing, 14."O"
ring, 15."O" ring, 16.Lube tube, 17."O" ring, 18.Snap ring, 19,Gasket,
20.Snap ring
To disassemble the removed synchromesh speed
transmission, first remove the speed gearbox cover (2) as follows:
Disconnect brake return hose from adaptor (4) and lube hose (11) from
lube tube (16). Remove snap ring (18) from lube tube (16). Make certain
shift levers (8 and 12) are in neutral position, then unbolt and remove
cover (2).
Remove lube tube (16) from gearbox. Disassemble of the cover and shift
levers is obvious after examination
of the unit and reference to Figures.
To remove shift forks (28 and 29), remove snap rings (27) from grooves
in shift rail (31). Drive roll pin (30) from the rail. Push the shift
rail forward and rotate rail about 1/2 turn to unseat detent balls from
slots in rail.
Move snap rings rearward on rail and continue moving rail forward. Cover
shift fork (28) with a shop towel to prevent losing detent ball (24) and
spring (25). Lift out shift fork (28). Remove shift fork (29) in same
manner.
Fig.6. Shift levers, shift forks and Interlocks used on Case
885, 485 synchromesh speed transmission
5."O" ring, 6.Housing, 7.Interlock pivot, 8.Shift lever (lst-2nd),
9.Housing, 10.'O" ring, 12.Shift lever (3rd-4th), 13.Housing, 14."O"
ring, 21.Interlock, 22.Shift arm, 23.Nuts, 24.Detent balls, 25.Detent
springs, 26.Dowel pins, 27.Snap rings, 28.Shift fork (1st-2nd), 29.Shift
fork (3rd-4th), 30.Roll pin, 31.Shift rail, 32.Shift arm, 33.Spacer,
34.Interlock support arm, 35.Interlock
Remove clutch release bearing and sleeve. Drive roll pins from release
fork, withdraw release shaft and remove fork. Unbolt and remove pto
driven shaft end cover and metal gasket. Remove snap ring from front end
of pto driven shaft.
Working through bottom cover opening, remove snap ring from pto driven
gear. Using a brass drift, drive the driven shaft rearward out of
bearing and remove bearing. Withdraw the driven shaft and have helper
remove gear as shaft is removed. Unbolt and remove clutch release sleeve
carrier, then withdraw pto drive shaft and gear.
Before removing the main shaft (3), use a dial indicator and check end
float between rear thrust washer (14) and second speed gear (13). End
float must be 0.004- 0.037 inch (0.102-0.94 mm).
Then, measure end float between front thrust washer (14) and fourth
speed gear (16). End float must be 0,0-0.076 inch (0.0-1.93 mm), if end
float is excessive, new thrust washers must be installed during
reassembly. Thrust washers are available in one size only.
Unbolt bearing cage (7) and slide main shaft (3), rearward far enough
for access to snap ring (15). Separate thrust washers (14) and remove
snap ring (15).
Withdraw the mainshaft assembly (1 through 9) and remove thrust washers
(14), second speed gear (13), synchronizer (12), hub (11) and first
speed gear (10) as shaft is removed.
Remove fourth speed gear (16), hub (17) and synchronizer (18). Remove
spacer (9) from mainshaft. Remove snap ring (4), then remove main shaft
and bearing (5) from bearing cage (7). Remove seal rings (8) and snap
ring (6), then press bearing (5) from mainshaft. If desired, remove snap
ring (1) and needle bearing (2).
Remove housing (27) with "O" ring (28) and bushing (29) from front of
speed gearbox. Remove transmission input (clutch) shaft (31) and bearing
(30) out through rear of speed gearbox. Press bearing from shaft.
Fig.7. Case 885, 485 tractors Synchromesh speed transmission
gears and shafts
1.Snap ring, 2.Needle bearing, 3.Mainshaft, 4.Snap ring, 5.Bearing,
6.Snap ring, 7.Bearing cage, 8.Seal rings, 9.Spacer, 10.1st speed gear,
11.Hub, 12.Synchronizer, 13.2nd speed gear, 14.Thrust washers, 15.Snap
ring, 16.4th speed gear, 17.Hub, 18,Synchronizer, 19.Needle bearing,
20.Oil seal, 21."O" ring, 22.Snap ring, 23.Bearing, 24.Pto drive shaft,
25.Oil seal, 26.Oil seal, 27.Housing, 28."O" ring, 29.Bushing,
30.Bearing, 31.Clutch shaft, 32.Snap ring, 33.Snap ring, 34.Bearing,
36.Snap ring, 36.Countershaft, 37.1st gear, 38.2nd gear, 39.4th gear,
40.Constant mesh gear, 41.Snap ring, 42.Needle bearing, 43.Cover,
44.Metal gasket, 45.Snap ring, 46.Bearing, 47.Pto driven gear, 48.Pto
driven shaft
To remove the countershaft (36), remove snap ring (41) from groove in
shaft. Remove snap ring (32), then using a brass drift, drive
countershaft rearward.
Remove snap ring (41) and gears (37, 38, 39 and 40) as shaft is
withdrawn. Remove snap ring (33) and press bearing (34) from
countershaft. Remove needle bearing (42) from gearbox.
Clean and inspect all Case 885, 485 tractor synchromesh speed
transmission parts and renew any showing excessive wear or other damage.
Check synchronizer friction faces and cups for excessive wear or other
damage.
Press down on synchronizer ring, then release, to check centering action
of springs. Synchronizers are serviced only as complete assemblies.
When reassembling, use all new "O" rings, seal rings, oil seals and
gaskets and reverse disassemble procedures. When installing countershaft
needle bearing, refer to Figure and install at distance shown. Apply
Loctite 515 to mounting surface of range section, then reconnect speed
gearbox to range section.
Tighten retaining bolts to a torque of 80 ft.-lbs, (108 N-m). Refill
transmission to level on dipstick with new Hy-Tran Plus fluid. Install
countershaft needle bearing (42) and pto ball bearing (46) as shown.
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CASE IH TRACTORS SPECIFICATIONS |
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CASE IH FRONT END LOADERS SPECS |
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