Rear axle - Trumpets with composite drive unit


The trumpets support the left-hand and right-hand side axle shafts and contain the final drive unit that transmits the rotation from the differential assembly. The trumpets are symmetrical and fitted on either side of the centre housing.

1

Construction
The axle shaft (2) is supported by two taper roller bearings comprised of cups (8) (12) and cones (7) (13mounted opposing each other. The oil tightness of the final drive unit is provided by lip seals (31) fitted back-to-back and o’rings (4). The cassette seal (3) protects the external bearing comprising cup (8) and cone (7). The planetary carrier (25) is separated from the centre housing by a spacer (30) that also serves as the brake plate. The compartment containing the final drive unit contains SAE 85W140 viscosity oil and is different from that used in the transmission.
Axial and radial drilled holes in pin (20) permit lubrication of the needle bearings (23) in the double sun gears. The planetary carrier drives the axle shaft (2) via splines and has three double pinions (22). The axial clearance of these pinions is provided by shim(s) placed on pin (20) against the 17-teeth pinion.
Shims (26) placed at the end of the axle shaft allow a preloading of the taper roller bearings. Shaft (2) and planetary carrier (25) are held by washers (27) and bolt (28). The reduction crown (15) squeezed between the trumpet (10) and spacer (30) is centred by pin (14). Spacer (30) is positioned by pin (5) on the centre housing. The rotation of the differential is transmitted to the double sun gears via a planetary gear shaft on which snap ring (33) retains hub (32) driving the brake disc (35).
The compartment of spacer (30) possesses a port "O" that provides for lubrication of the brakes. Tube (38) linked to the breather tube screwed on to the left-hand lift support allows atmospheric pressure to be maintained in the trumpet.

Kinematics (Fig. 2)
The differential assembly drives the sun gear shaft (29) that in turn transmits the movement to the axle shaft (2) via double planetary gears (22), crownwheel (15) and planetary carrier (25). It is a classical kinematics train: the movement enters the sun gear shaft and is output to the planetary carrier.

3

Parts list
(1) Bush (2) Straight shaft (3) Cassette seal (4) O’rings (5) Locating pin (6) Shim(s) (7) Bearing cone (8) Bearing cup (9) Washer (10) Trumpet (11) Nut (12) Bearing cup (13) Bearing cone (14) Pin (15) Crownwheel (16) Tab washer (17) Spacer (18) Bolt (19) Circlip (20) Planetary gear pin
(21) Washer (22) Double planetary gear (23) Needle bearings (24) Spacer (25) Planetary carrier (26) Shim(s) (27) Lock washer (28) Bolt (29) Sun gear (30) Spacer (brake plate) (31) Seals (32) Splined hub (33) Snap ring (34) Stud (35) Brake disc (36) Studs (37) Stud (38) Tube (40) Bolt (41) Plug (filler and level) (43) Magnetic drain plug

2

Removing and refitting the trumpet Assembly


Drain the centre housing.
- The oil used for the mechanical and hydraulic components of the transmission and that used for the lubrication of the moving parts of the trumpet are not of the same type and their viscosity is different.
- If the oils are not to be changed, they must not be mixed when drained.
Immobilise the tractor. Take off the wheel. Position an axle stand.
Remove the cab fixing bolts and the stabiliser support.
If necessary slightly raise the side of the cab concerned, check that nothing blocks its lifting.
Position an axle stand.
Drive out the holding snap ring. Push the lower axle (2) of the lift ram outwards and remove it.
Support the trumpet using appropriate support and trolley jack.
Remove the nuts (11) and washers (9) but exclude bolt (40).
Separate the centre housing, the trumpet assembly from the sun gear (29), the spacer assembly (30bearing the markings (31) to (33) - (35) and crownwheel (15) (Fig.4).

4

- The brake piston "P" remains in the housing (1) (Fig.4).
- The threaded studs (34) (36) (37) screwed into the centre housing have different lengths and their threads must be lightly smeared with Loctite 270 or equivalent before fitting.
- Place the studs in the housing, respecting their length and locations in accordance with Fig.1 :
. (34) : Ø 16 mm - L 335 mm
. (36) : Ø 16 mm - L 353 mm
. (37) : Ø 16 mm - L 363 mm
Clean the mating faces of the trumpet and centre housing. Remove all traces of previous sealing compound. Dry the parts.
Place a bead of sealing compound (Silicomet type) in angle "D" of the centre housing (1) (Figs.5).

5

- The diameter of the bead must be uniform, of small section and without joins.
Install the brake disc (35) while checking that it slides freely on the splines of the hub (32). Check for the presence of the locating pin.
Support the trumpet with the aid of the equipment used when removing it.
Engage the trumpet on the original studs. Turn the axle shaft and push the trumpet until it mates with the housing.
Place a washer (9) on each stud. Screw on the nuts and tighten to a torque of 247 - 253 Nm.
Replace the components surrounding the trumpet. Install the wheel and tighten the bolts and nuts to the correct torque depending on the version.
Tightening torques
- cab fixing bolts (silent bloc): 200 - 260 Nm. Loctite 270 or equivalent.
Top up the oil level of the housings and check using the transparent tube located on the left-hand side of the centre housing.
- Equally, check the level of oil in the drive unit concerned.
Check the operation of the lift control. Carry out a road test of the brake circuit. Check the oil tightness of the trumpet, hydraulic unions and plugs.

Removal and install the spacer and crownwheel assembly

Remove the trumpet assembly and drain the drive unit concerned.
If possible, place the trumpet in a vertical position, the sun gear (29) at the top. Remove bolts (40), snap ring (33) and hub (32). Unstick and remove the spacer (30) having previously placed a flexible protection on the splines of the sun gear (29). Take off the sun gear.
Remove the planetary carrier assembly. Unstick and remove the crownwheel.
Discard the o’rings (4) (Fig.1).
Clean the mating faces of the trumpet, crownwheel and spacer with solvent. Dry the parts.
Position new crownwheel o’rings according to the arrows in angles B and C between the trumpet (10) and compartment (30).
Replace the trumpet assembly and the sun gear. Fit protector ref. 3376885M1, the spacer (30), hub (32), snap ring (33). Fit and tighten the bolts (40) to a torque of 100 - 130 Nm.
Replace the trumpet assembly and top up and check the drive unit oil level.

6

Replacing the spacer seals

Remove the trumpet assembly.
Remove the spacer assembly (30) and crownwheel.
Extract the seals (31).
Using a suitable fixture, insert the first new seal against the shoulder of the spacer and the second seal back-to-back using the same method.
Install the spacer assembly (30) and the crownwheel.
Install the trumpet assembly.

Replacing the cassette seal

Partially drain the concerned drive unit.
Chock the front wheels. Remove the rear wheel. Place an axle stand beneath the trumpet.
- Tractors may be fitted with axle shafts of 95 mm or 110 mm diameter.
- Whatever the diameter of the shaft, the reference number for bush (1) and cassette seal (3) (Fig.7) remains identical.
- If necessary, smear the bore of the bush with Loctite 648 or its equivalent and slide it on to the shaft flush with the thrust face of bearing cone (7) (Fig.7).

7

Using a locally manufactured tool, extract the cassette seal, without damaging the trumpet or the external diameter of the bush.
Clean the location of the seal on the trumpet and bush.
Lightly smear the external diameter of the seal with Loctite 648 or its equivalent and moderately lubricate its internal diameter with transmission oil.
Insert the seal using tool ref. 3378151M1. Wipe off all remaining traces of Loctite.
- The design of the tool determines the position of the cassette seal in the trumpet.
Install the wheel and tighten the wheel studs or nuts depending on the version.
Top up and check the oil level in the drive unit.
Road test. Check the oil tightness of the cassette seal.

Removing and dissassembling of the planetary carrier

Remove the trumpet assembly.
Remove the hub (32), spacer (30) and the sun gear shaft (29).
Immobilise the axle shaft and planetary carrier.
Take out bolt (28), washer (27) and the shim(s) (26). Remove the planetary carrier assembly using an appropriate sling.
Take out the crownwheel.
Take out boltand spacer. Take off the circlip by opening its extremities.
Drive out and remove the pins (20). Remove the friction washers (21), shim(s) (6) and planetary gears (22). Recover the two rows of needle bearings (23) separated by spacer (24) (Fig.8).

8

Reassembling and install the planetary carrier

Clean and check the components. Replace any parts found to be defective.
Coat the needle bearings (23) with miscible grease. In each of the planetary gears (22), place two rows of needle bearings separated by spacer (24).
If necessary, carry out axial shimming of the planetary gears, otherwise continue with the reassembly operation.
Place the planetary gear (22) in the planetary carrier (25) with the 17 teeth pinion facing the circlip (19). Place washers (21) and shim(s) (6).
Engage the three pins (20) and turn the lubricating ports "O" towards the circlip (19) (Fig.9).
Push again on the three pins and open the circlip.
Tap lightly and alternately on the pins to ensure that the circlip correctly fits in the groove of the planetary carrier (Fig.9).

9

Place spacer (17), fit and tighten bolt (18) previously lightly smeared with Loctite 270 or its equivalent and tighten to a torque of 34 - 50 Nm (Fig.10).
Manually check the rotation of the planetary gears.

10

Install the crownwheel.
Check for the presence of washer (16). Refit the planetary carrier assembly turning the marks stamped on each planetary gear to the correct position. If necessary, carry out shimming of the axle shaft bearings. Otherwise, continue the refitting operation.
- Each planetary gear carries a punched mark on the 29 teeth pinion. These marks indicate the alignment of two teeth belonging to their respective pinions (17 and 29 teeth). The marks must point towards the centre of the planetary carrier.
Immobilise the axle shaft and the planetary carrier. Place the shim(s) (26) and washer (27). Fit and tighten bolt (28) previously lightly smeared with Loctite 270 or equivalent and tighten to a torque of 340 - 500 Nm.
Install the sun gear shaft (29), spacer (30) and hub (32).
Install the trumpet assembly and top up and check the oil level in the drive unit concerned.

Shimming the planetary gear

- The planetary carrier (25) comprises three double pinions (22) also known as planetary gears. The axial clearance of these pinions is obtained via shim(s) (6) placed on pin (20) against the 17 teeth pinion.
Place the planetary gears (22), the 17-teeth pinion facing the circlip (19). Place washers (21) against the 29 teeth pinion and average thickness provisional shim(s) (6) against the 17 teeth pinion.
Engage the three pins (20), turning the lubricating ports towards the circlip (19).

Shimming
Using a feeler gauge determine the thickness of the definitive shim(s) to be fitted so as to obtain a clearance of between 0.15 mm and 0.6 mm on each planetary gear.
Where possible shim to the minimum tolerance.
Slightly retract the pins and place the shim(s) whose thickness was previously determined.
- The thickest shim must be placed against the row of needle bearings.
Install the pins. Install circlip (19). Position the spacer (17) and tighten bolt (18), previously lightly smeared with Loctite, to a torque of 34 - 50 Nm.

Replacing the axle shaft bearings

Remove:
- the trumpet assembly
- the spacer assembly (30)
- the planetary carrier (25)
- the crownwheel
Take off washer (16) and shaft assembly (2).
- The bearing cone (13) runs free on the shaft.
Remove the bearing cone (13). Extract bearing cone (7).
Drive out the cassette seal (3).
Using an extractor or locally manufactured tool, remove bearing cups (8) (12).
Clean and check the components. Replace any parts found to be defective.
Insert:
- bearing cups (8) (12) thrusting against their respective shoulders
- bearing cone (7) previously lubricated with transmission oil and thrusting against the shoulder on the shaft.
Introduce the prepared shaft into the trumpet fitted with its cups.
Assemble cone (13) and refit tab washer (16).
Place the crownwheel. Refit the planetary carrier assembly (25) and carry out shimming of the bearings.
Install the spacer assembly (30).
Install the trumpet assembly.
Insert a new cassette seal.
Install the wheel and tighten the wheel nuts or studs to the correct torque depending on the version.
Top up and check the oil level in the housings and check the level in the transparent tube located on the left-hand side of the centre housing. In addition, top up and check the oil level of the drive unit concerned.

Shimming the axle shaft bearings

Components concerned by shimming
- The axle shaft (2), taper roller bearings (7) (8) (12) (13), the trumpet and tab washer (16).
- The shimming for pre-loading of the taper roller bearings on the axle shaft is carried out using shim(s) (26) placed between the end of shaft (2) and washer (27) (Fig.11).

11

- To carry out the correct shimming of the bearings, place the trumpet in a vertical position (Fig.11).
With bearing cone (13), tab washer (16) and planetary carrier (25) fitted, place a thickness of shim(s) (26) greater than the space between the end of the axle shaft (2) and the thrust face of washer (27) on the planetary carrier (Fig. 25) to obtain a provisional clearance of approximately 0.10 mm to 0.15 mm, in order to carry out definitive shimming.
Place washer (27). Provisionally tighten bolt (28).

Shimming (Fig.12)

12

Press hard on the planetary carrier while simultaneously turning the trumpet several times.
Place a dial gauge on the planetary carrier (Fig.12), the index positioned close to the axis of the trumpet.
Set the dial gauge to zero.
Using appropriate levers, move the planetary carrier vertically.
In relation to the clearance "J", remove a thickness of shim(s) (26) necessary to obtain a pre-loading of: P1 = 0.02 mm to 0.12 mm (Fig.11) according to : J - (0.02 to 0.012).
Definitively fit washer (27) and tighten bolt (28) previously lightly smeared with Loctite 270 or its Equivalent.