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Massey Ferguson 8220, 8280 heavy gearbox – Mainshaft
The mainshaft (7) fitted to Massey Ferguson 8220, 8280 Heavy gearboxes rotates on two taper roller bearings (9) (10) and (20) (21) lying in the two lower bearings of the main gearbox.
The input gear (1) fitted at the front, engages with the shaft via splines. It is held by Belleville washers (2) fixed by the special cone-locking bolt (3).
The Belleville washers also provide a constant load on bush (8), the synchromesh hub (16) and the shoulder of the shaft. This flexible assembly permits permanent contact of the stated parts, when forces are applied to the gears.
Between the two lower bearings, the shaft bears the freely rotating driving pinions of 2nd gear (13) and 1st gear, as well as the synchromesh assembly of 1st and 2nd, the hub of which engages splines on the shaft.
At the rear, it bears the freely rotating driving pinion of 4th gear (24) and the synchromesh assembly for 3rd and 4th gear. The rear bore receives bearing cup (22) of the taper roller bearing of the output shaft.
The lubrication of 1st gear pinion and the bush of the 2nd gear pinion are ensured by a central channel and radial drillings. The preloading of the bearings is adjusted by means of shims (11) placed behind bearing cup (10).
The input pinion (1) is shimmed by means of shims (38) (39) fitted on
the special bolt (3) to obtain a flexing of the Belleville washers (2).
(1) Input pinion (2) Belleville washers (3) Special bolt (4) Lubricating
pipe (5) Snap ring (6) Spring (7) Mainshaft (8) Bush (9) Bearing cone
(10) Bearing cup (11) Shim(s) (12) Spacer (13) 2nd gear pinion (14) 2nd
gear synchromesh bearing cone (15) 2nd gear synchromesh ring (16) 1st -
2nd synchromesh (17) 1st gear synchromesh ring (18) 1st gear synchromesh
bearing cone (19) 1st gear driving pinion (20) Bearing cone (21) Bearing
cup (22) Bearing cup (24) 4th gear driving pinion (25) 4th gear
synchromesh bearing cone (26) 4th gear synchromesh ring (27) 3rd - 4th
synchromesh (29) Snap ring (30) 3rd gear synchromesh ring (32) 3rd gear
synchromesh bearing cone (38) Shim(s) (39) Spacer
To dismantle the mainshaft, it is necessary to remove the gearbox.
Uncouple the MF 8220, 8280 tractor between the gearbox and the
intermediate housing.
Separate the gearbox from the engine.
Remove the selector cover.
Place the gearbox on a suitable fixture.
Take off the input unit.
Remove the selector rails and forks.
Remove the output shaft.
Disassembling and reassembling the shaft
To remove the bearing cone (25), the synchromesh (27) and the 4th gear
driving pinion (24), it is necessary to remove circlip (56) from the
machined throat of the
mainshaft. Then to push back pinion (57).
Take off the snap ring (29). Remove 3rd - 4th gear synchromesh (27) and
mark its position.
Remove the synchromesh ring (26), the bearing cone (25) and the pinion
(24).
Keep the synchromesh ring and bearing cone together if they are to be
re-used.
Keep the shaft under rotation by using a locally manufactured tool and
by using a MF 8220, 8280 4 WD clutch.
If necessary, remove lubricating pipe (4) and spring (6).
Unscrew bolt (3) by means of a 32 mm socket and a suitable length
extension.
Remove shims (38) (39), Belleville washers (2) and input pinion (1).
Remove bush (8) fitted with cone bearing (9).
Remove the tool. Take out the shaft from its housing with the 1st gear
pinion (19) located at the rear, through the bearing aperture, while
maintaining the fork, pinion
and 1st - 2nd gear synchromesh assembly.
The extracting of the 1st - 2nd gear fork from the housing must be
accompanied by the synchromesh assembly (16) and the 2nd gear driving
pinion (13).
Remove the whole assembly (synchromesh, 2nd gear pinion assembly and
fork) through the selector cover aperture.
Take off the bearing cups (10) (21).
In the case of re-use, keep cups and cones together.
Remove shims (11), spacer (12).
Where necessary, extract the bearing cones (9) (20), cup (22). Take off
snap ring (5) from bolt (3).
Clean and inspect the components. Replace any defective parts.
Check that the central channel and radial ports of shaft (7) are not blocked. If disassembled, with the aid of a press and a suitable fixture, respectively insert bearing cones (9)(20) on bush (8) and shaft (7).
Position the snap ring (5) in bolt (3).
Insert bearing cup (22) in shaft (7).
Lubricate the bearing cones and cups.
Install cup (21).
Place the spacer (12), the shims (11) selected during operation 59 and
the bearing cup (10) in the bore of the housing.
The shims (11) must be fitted between the spacer (12) and the bearing
cup (10).
Check for wear on syncromesh rings (15) (17) against bearing cones (14)
(18).
Assemble the 2nd gear pinion (13), bearing cone (14), synchromesh ring
(15), 1st - 2nd gear synchromesh (16), 1st gear synchromesh ring (17)
and bearing cone
(18) on the workbench.
Install the entire assembly between the separations with the 1st - 2nd
gear fork correctly positioned.
Slide in the shaft and 1st gear pinion (19) through the rear of the
housing while holding the pinion / synchromesh assembly.
Slide synchromesh ring (8) fitted with bearing cone (9) on to the shaft
(7).
Install the pinion (1), the Belleville washers (2) positioned, and the
shims (39) (38) determined during operation, along with bolt (3).
The shims (38) must be placed against the shoulder of the bolt (3).
Hold the shaft in place. Tighten bolt (3) lightly smeared with Loctite
270 to a torque of 320 - 360 Nm. Remove the tool. Manually check the
rotation of the shaft.
If disassembled, fit spring (6) and lubricating pipe (4) with bolt (3).
Check for wear of synchromesh ring (26) against cone (25).
Install the pinion (24), cone (25), synchromesh ring (26) and the 3rd -
4th gear synchromesh (27) while respecting the direction of assembly.
Advance pinion (57) on the intermediate shaft and place circlip (56) in
the throat without bending it and ensuring that it is correctly fitted.
Place snap ring (29).
Manually check:
- the axial clearance of the pinions
- the rotation of the shaft and its gear train.
Install the output shaft.
Install the input unit.
Install the selector rails.
Adjust the forks and selectors of 1st - 2nd and Hare / Tortoise. Replace the selector cover.
Check that changing of the gears is
correctly carried out and that the Hare / Tortoise position is present.
Connect the Massey Ferguson 8220, 8280 gearbox to the engine.
Reconnect the tractor between the gearbox and the intermediate housing.
Check the oil tightness of seals and hydraulic unions.
Road test the clutch controls, the reverse shuttle, the Hare / Tortoise
range of gears and the A, B, C, D ratios of the Dynashift.
Shimming the input pinion
Place the shaft (7) in a vice fitted with jaw protectors. Provisionally
fit the synchromesh (18), the ring (8), input pinion (1), the Belleville
washers (2) without the shims
(38) (39). It is essential that special bolt (3) is tightened to a
torque of 30 Nm maximum.
Place the dial gauge index on the end of the shaft, measure axial
clearance of pinion (1).
In relation to the clearance measured and the thickness of the shim
removed (39), select shim thickness (38) to obtain a flexing of the
Belleville washers of between
1.25 mm and 1.75 mm.
If the axial clearance is greater than 1 mm, it is recommended to reduce
it by adding only one shim (38) in order to measure it again with
greater precision.
Take out bolts (3) and the elements provisionally fitted. Go on with the
final assembly of the shaft and carry out its shimming.
In cases where input pinion (1) is replaced on MF 8220, 8280 the
tractor, the shimming method is identical. First temporarily remove the
cup (10) and shims (11)
(12) in order to eliminate the preloading effect on bearings (9) (10)
and (20) (21). When the shimming of the pinion is completed, replace the
shims and the cup.
Shimming the shaft
Determine the thickness of the shim(s) (11) in order to obtain a
temporary clearance of approximately 0.10 mm to 0.15 mm, while awaiting
the shimming with
preloading. It is essential to place the spacer (12) against the
housing, previously determined shims (11) and cup (10).
Install the shaft locking tool. Tighten bolt (3). Remove the tool.
Proceed with the shimming.
Place the index of the dial gauge on the end of shaft (7).
From the front of the housing, pull hard on the shaft while turning it
left and right to seat it correctly in the bearing cups and cones.
Reset the dial gauge to zero.In relation to the clearance read on the
gauge, select the correct thickness for the definitive shims (11) in
order to obtain a preloading of:
P1 = 0.10 mm to 0.20 mm maximum.
Install the locking tool on the shaft. Unscrew bolt (3). Take off the
shims (38) (39), the Belleville washers (2) and the pinion (1).
Take out bush (8) fitted with bearing cone (9) and cup (10).
Place the shims (11), selected in operation 59, between spacer (12) and
cup (10).
Install bush (8) fitted with cone (9), pinion (1), Belleville washers
(2) and shims (38) (39) placed.
Tighten bolt (3) smeared with Loctite 270 to a final torque of 320 - 360 Nm. Remove the tool. Manually check the rotation of the shaft and its gear train.
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