ZF front axle - final drive units

The tractors are fitted with ZF front axle APL 5052. A plate riveted on the rear right-hand side of the main housing indicates the serial number and type, as well as certain front axle specifications.
The ZF front axle final drive unit assembly is fitted on a swivel housing (13) that is articulated on the main housing (1) via two swivel pins (16). Two taper roller bearings (33) (36) and (37) (38) fitted in the wheel hub (34) ensure the rotation of the latter. The movement from the front differential is transmitted to the wheel hub via universal drive shaft (12), sun gear (45) and crownwheel (41). The latter is retained by snap ring (39) on planetary carrier (40). Oil tightness is ensured at the final drive unit by a lip seal (32) and at the universal drive shaft / main housing by seal (9).
Oil tightness is ensured at spindle (30) and universal drive shaft (12) by seal (28) and at swivel bearings in housing (13) by O’ring (7).

ZF front axle final drive Parts list
(1) Axle housing (2) Breather (4) Bearing cone (5) Bearing cup (6) Deflectors (7) O’ring (8) Bush (9) Seal (10) Dust cover (12) Universal drive shaft (13) Swivel housing (14) Steering lock adjustment screw (15) Nut (16) Swivel pin (17) Shims (18) Arm (19) Mecanindus pin dia.12 (20) Mecanindus pin dia. 20 (21) Bolt (22) Grease nipple (23) Lower cover (24) Bolt (25) 45ยบ grease nipple (27) Dust cover (28) Seal (29) Bush (30) Spindle (31) Bolt (32) Seal (33) Bearing cone (34) Wheel hub (35) Stud (36) Bearing cup
(37) Bearing cup (38) Bearing cone (39) Snap ring (40) Crownwheel carrier (41) Crownwheel (42) Castellated nuts (43) Stop (44) Tab washer (45) Sun gear (46) Snap ring (47) Tab washer (48) Shim (49) Planetary carrier (50) Bolt (51) Planetary gear pin (52) Snap ring (53) Bearing cup plug (54) Seal
(55) Plug (56) Friction washer (57) Washer (58) Planetary gear (59) Needle bearing

Removing and install the planetary carrier, sun gear, crownwheel and wheel hub

Chock the rear wheels. Put the handbrake on.
- The 4WD clutch is mechanically engaged when the tractor is stationary and the engine turned off. Raise both front wheels so as to freely turn the hub of the wheel concerned.
Place axle stands beneath the ZF front axle. Take off the wheel concerned.
Drain the final drive unit.

Special point
- The drain port machined into the planetary carrier (49) is aligned with a moulded cavity on wheel hub (34), in order to allow for the correct evacuation of the lubricating oil when draining. For this reason, the position of the planetary carrier on the hub must be located by two opposing paint marks T before disassembly.

Remove bolts (50) and separate the planetary carrier assembly from the hub using two extractor bolts “V”, ref. 5870 204 016.
Take off snap ring (46), sun gear (45) and tab washer (44).
Correctly unlock the two castellated nuts (42) and successively unscrew them using socket, ref. 5870 401 082. Discard the retainer (43).
Extract the wheel hub (34), crownwheel carrier (40) and crownwheel (41). Remove the assembly using a lifting device. Where necessary, match and keep together bearing cones (33) (38) and bearing cups (36) (37).

If required, remove snap ring (39) and separate crownwheel (41) from the crownwheel carrier (40).
If the crownwheel has previously been separated from the crownwheel carrier, Install the two together and Install the snap ring (39).
If required, replace lip seal (32) that provides oil tightness for the wheel hub.
Reinstall the wheel hub, the crownwheel carrier and crownwheel, using the same safety precautions and method as when removing it.

Adjust the rotational torque of the wheel hub.
Check or carry out shimming of the planetary carrier.
Lightly smear the mating face of the planetary carrier with the hub with Loctite 510 or its equivalent, taking care that it does not enter the tapped holes.
Screw two diametrically opposed guide studs into the hub.
Check for the presence of tab washer (47) in the cavity in the planetary carrier.
Position the planetary carrier according to the paint marks made during its removal.
Install bolts (50) and tighten to a torque of 190 - 220 Nm.
Turn the wheel hub in order to Install the oil filler plug in the horizontal axis of the drive unit. Top up the oil level using an oil with a viscosity grade of 80W/90 and check the oil level through the same port. Screw in plug (55) fitted with its seal (54).
Reinstall the wheel. Remove the axle stands and trolley jack. Tighten the wheel nuts to a torque of 575 Nm.
Remove the chocks and release the handbrake.
Carry out a road test. Check for the oil tightness of the mating face of the planetary carrier and the drain and filling plugs.

Disassembling and reassembling the planetary carrier

Remove the planetary carrier.
Place the planetary carrier in a press fitted with an appropriate fixture.
Extract pins (51) from the planetary carrier (49), pulling outwards as shown by “P”.

- Each pin is fitted with a snap ring (52).
Recover the friction washers (56), washers (57) and needle bearings (59) from each bearing.
Clean and inspect the components. Replace any parts found to be defective.
In the planetary gears (58), arrange the needle bearings coated with bearing grease. Place a washer (57) on either side of each planetary gear.
Position the friction washers (56), with each tab located in the groove of the planetary carrier. Slide the pre-assembled planetary gears between the friction washers.

Check for the presence of snap ring (52) on the planetary gear pins. Centre the planetary gears and friction washers. Position and insert the pins (51) thrusting against the planetary carrier via its external face using the same equipment that was used for their removal.
Manually check the axial clearance and the free rotation of each planetary gear. Install the planetary carrier.

Replacing the lip seal and wheel hub bearings

Remove the wheel hub.

Replacing the seal (32)
Locate the position of the seal and extract it using a local method.
Inspect and clean the seal location. Check for any shock or scratching that could affect the oil tightness of the hub.
Insert the new seal in the hub into the previously noted position using an insertion tool made up from centring bush, ref. 5870 905 005, drift, ref. 5870 055 073 and handle, ref. 5870 260 002. Lubricate the lips of the seal.

Replacing the bearings
Extract seal (32) and discard it.
Extract the bearing cups from the wheel hub (34) using a local method.
Discard the cones (33) (38) and bearing cups (36) (37).
Clean and visually check that the cone and cup locations are free from burs. Lubricate the bearings.
Insert new cups on the shoulders of the hub using a press and an appropriate fixture. Reinstall the wheel hub. Adjust the hub rotational torque.
Check or carry out the shimming of the planetary carrier.

Adjusting the rotational torque of the wheel hub

- This adjustment is carried out during the replacement of the taper roller bearings or the wheel hub.

Install internal nut (42) and tighten it using socket, ref. 5870 401 082, so as to obtain a rotational torque of:
- 7 to 13 Nm for new bearings
- 3.5 to 6.5 Nm for re-used bearings
- The rotational torque is checked using a spring balance and a wire wrapped around the circumference of hub (34).
Place the retainer (43). Screw and lock the external nut (42) using the socket.

Special point
- Retainer (43) is fitted between two nuts (42). By means of two tabs lodged in the grooves on spindle (30) it stops any rotation of the internal adjusting nut during the tightening of the external locking nut.
Using an appropriate tool, lock nut (42) by bending the retainer (43), without breaking it, into one of the six notches on each nut.

Shimming the planetary carrier

- The shimming of the planetary carrier consists of obtaining a J1 clearance of 0.3 to 0.5 mm between the end of the universal drive shaft (12) and the bottom of the planetary carrier (49).

Install the tab washer (44) with its tabs positioned in the notches on spindle (30). Slide the sun gear (45) on to the end of universal drive shaft and fit snap ring (46).

- Push hard on the universal drive shaft in order that the sun gear thrusts against the spindle.

On the wheel hub (34) 

Measure dimension A between the thrust face of the planetary carrier on the hub and the end of the universal drive shaft (12).

On the planetary carrier (49) 

Measure dimension B between the thrust face of the planetary carrier and the tab washer (47).
Determine J1 using the formula: B - A
- If J1 is between 0.30 and 0.50 mm, the shimming is correct. Otherwise, extract cup plug (53). Release and drive off tab washer (47) to add or remove shims (48) in order to obtain the correct J1 clearance.

After carrying out the shimming, reinstall:
- the previously selected shims
- the thrust washer, its rim lightly smeared with Loctite
- a new cup plug, its circumference lightly smeared with Loctite 542 or its equivalent.