AG 155/200 Dana Front axle - Differential

Whatever the type of front axle installed on some series tractors (AG 155H or AG 200H), the operating principles and maintenance procedures remain similar.

AG 155H type

AG 200H type

Note however that the splined end of the drive pinion is different on AG 200H Dana front axles. This amendment allows for a semi-rigid link between plate (45) and the drive shaft. Some tractor models have a ZF front axle fitted with a bevel gear of the same type. The bevel gear assembly containing the differential lock mechanism is fitted in a housing (35) that has two half bearings held by bolts (42). The drive pinion is placed at the rear of the housing on two opposing taper roller bearings. Its adjustment is carried out via shim(s) (28) located behind the leading bearing. The preloading of the bearings is obtained via shim(s) (34) placed between bearing cone (32) and the shoulder of the drive pinion. The oil tightness is provided by seal (31) and O’ring (29) fitted on the drive pinion. The adjustment of the crownwheel / drive pinion is obtained via shim(s) (11) placed behind bearing cup (12).
The preloading of the housing and crownwheel assembly is carried out via splined nut (24). A plate riveted on the right-hand side of the housing indicates the type and serial number of the front axle.

Parts list
(1) Snap ring (2) Tab washer (3) O’ring (4) Piston (5) Friction washer (6) Spring (7) Locating pin (8) O’ring (9) Guiding washer (10) Washer (11) Shim(s) (12) Bearing cup (13) Bearing cone (14) Bolt (15) Cover
(16) Half-housing (17) Planetary gear (18) Spherical washer (19) Planetary gear pins (20) Bolts (21) Sun gear (22) Bolt (23) Lock washer (24) Splined nut (25) Washer (26) Half-housing (27) Crownwheel (28) Shim(s) (29) O’ring (30) Nut (31) Seal (32) Bearing cone (33) Bearing cup (34) Shim (35) Housing (36) Deflector (37) Bearing cup (38) Bearing cone (39) Drive pinion (40) Mobile coupler (41) Half-bearing (42) Bearing block bolt (43) Centring bush (44) Wear ring (45) Plate (46) Washer

Removing the Dana differential housing Assembly
Remove the swivel housing, wheel hub and drive shaft assembly. Remove the bolts holding the steering ram and remove it.

Take out bolts (1). Release and remove the differential housing assembly (35). If necessary, remove the deflector (36).

Disassembling the Dana differential

Place housing (35) in a vice fitted with soft jaws. Remove bolt (22) and its lock washer (23).

Remove the splined nut (24) using a special locally manufactured wrench.
Take out the four bolts (42), remove the half-bearing (41).
Remove the entire differential assembly with bearing cones (13) and cups (12). Separate the cups and cones. Remove shim(s) (11).

- If the bearings are to be reused, take care to match the original cups and cones.
If necessary, extract the two cones (13). Place the differential assembly in a vice fitted with soft jaws. Remove bolts (20) and disassemble the
crownwheel (27). Before disassembly, mark the position of halfhousings (16) (26) and cover (15). So that they can be matched at reassembly. Remove bolts(14) and separate the half-housings (16) and cover (15).
Remove the sun gear (21) and the washer (25).

Separate the two pins (19), the planetary gears (17) and the spherical washers (18).

Removing the differential lock 

Using tool correctly centred, compress spring (6) until washer (10) is released. Remove washer (10). Progressively, release the spring (6). Remove the tool.

Remove the spring guiding washer (9). Remove the spring (6). Disassemble the snap ring (1) of coupler (40). Remove the mobile coupler (40), friction washer (5) and tab washer (2). Remove piston (4). Take off the O’rings (3) (8).

Removing the crownwheel and drive pinion

Removing the crownwheel
- The replacement of the crownwheel (27) necessarily requires replacement of the drive pinion (39). Both the crownwheel and drive pinion have the same number engraved on them and they must be fitted as matched pairs.
Take out bolts (20) and remove the crownwheel (27).

Removing the drive pinion
Unlock nut (30).

AG 155H Dana front axles
Unscrew the drive pinion clockwise using wrench ref. 3378051M1 and a locally manufactured special sleeve “C”.

AG 200H Dana front axles
Unscrew the drive pinion clockwise using wrench ref. 3378275M1 and flange ref. 33782267M1. Take out of the housing the drive pinion, cone (38), shim (34) and O’ring (29) assembly.

Separate the drive pinion, seal (29), shim (34). Extract cone (38) from the drive pinion. Extract cup (37) and remove shims (28). Extract seal (31). Remove cone (32) and drive off cup (33).

Refitting the drive pinion and Crownwheel

Before reassembly, clean and inspect all components and replace any parts found to be defective. Check that the oil channel of the differential lock is not obstructed.

Refitting the drive pinion
Adjust the position of the drive pinion. The thickness of shims necessary to correctly position the drive pinion is calculated using the following formula:

SP = C - E - (d ± r)
SP : Thickness of shims necessary (28)
C : Distance measured between thrust face of cup (37) on housing (35) and machined face F.
d : Nominal distance of positioning drive pinion on axles:
- AG 155H= 133.5 ± 0.10
- AG200H = 139 ± 0.10

E : Thickness of bearing (37) (38).
r : Actual dimension marked on drive pinion. This value may be either positive or negative (add or deduct from nominal dimension d).

Measure dimensions C and E using a depth gauge. Take care to correctly seat cone (38) in cup (37). When the dimensions are measured, apply the formula in order to determine the thickness of the shims required.
Insert the cone thrusting against the shoulder on the drive pinion using a press and a suitable fixture.

Place the previously calculated thickness of shim(s) (28) in the housing.
Insert cup (37) using an appropriate fixture.
Carry out the shimming of bearings (32) (33) (37) (38).

Place the prepared drive pinion in the housing (35) thrusting against the cylindrical sleeve M as shown in Figure. Turn the housing several turns while applying a strong pressure to correctly seat cone (38) in cup (37).
Using an appropriate depth gauge, measure dimension F in accordance with the formula A - B.
Press hard on cup (33) while turning it alternately left and right in order to correctly seat cone (32). Measure dimension G.

Determine thickness SP1 of shim (34) using the formula:
(G + F) – 0.05 (0.05 mm being the preload value).
Place cup (33) thrusting against the housing. Slide the shim(s) (34) determined during operation on to the drive pinion. Fit cone (32) and seal (29) previously lubricated.

Grease seal (31) and insert it home in the shoulder using a locally manufactured tool.

AG 155H front axles
- Assemble nut (30) lock it using wrench ref. 3378051M1. Using a special sleeve and a torque wrench, turn the drive pinion then tighten to a torque of 450 - 500 Nm.

AG 200H front axles
- Assemble nut (30) and lock it with wrench ref. 3378275M1 and flange ref. 3378276M1, then tighten to a torque of 450 - 500 Nm.
Check the rotation torque of the drive pinion.

On AG 155H front axles, turn the drive pinion several turns using a dial torque wrench and the special sleeve on AG 200H front axles use wrench ref. 3378275M1. Check that the rotation torque of the drive pinion is between 2 to 4 Nm.

Refitting the crownwheel
- When repairing, use the bolts referenced in the spare parts catalogue.
Clean the mating faces of the new crownwheel and housing. Degrease the new bolts and lightly smear with Loctite 270 or equivalent and screw them into the crownwheel. Tighten all the bolts to a torque of 140 - 155 Nm.