GBA25 gearbox - Removing and install the Powershift module


Drain the transmission oil. Split the tractor between the engine and the gearbox.
Remove:
- either the complete gearbox (if servicing is to be carried out on the whole transmission assembly)
- or only the Powershift module from the unit, leaving the mechanical unit coupled to the rear axle (if servicing is to be carried out on the Powershift module or reverse shuttle only)


Remove:
- all hydraulic pipes fitted to the unit housing
- the unit control hydraulic unit with its connecting pipes
- the union and the lubrication pipe of the Powershift module
- the PTO shaft



If the whole unit has been removed, separate the Powershift module from the mechanical gearbox.
Rig up four makeshift legs on which to set the unit vertically. Use an M14 screw or threaded rod, and weld on a nut to ensure a minimum distance of 120 mm between the unit and the work surface.
Unscrew the two diametrically opposed screws (A) and replace them with two shackles to sling the gearbox. do not remove screws (C). They hold the front epicyclic gear train housing (D) in place.


Sling the gearbox Powershift module using the shackles.
Make a mark (R) on the housings to ensure the modules are refitted correctly.
Install the Powershift module on a supporting fixture positioned on the forward clutchTake out the screws holding the cover (26) on the housing (D).


Using the sling, lift and separate the front part of the Powershift module. During this step, the brake, the clutch and the rear planet carrier stay on the Power Shuttle. Sling the Powershift module.
Check that the return springs (S) are present in the cover (26).
Carry out step in reverse order, aligning the two parts using the mark (R). Take care when inserting the planetary gears in the Powershift module brake piston (57).


Install the cover screws (26) to the Powershift module, after smearing them with Loctite 242 or equivalent. Tighten the screws to a torque of 66 Nm.
Clean the mating faces then apply Loctite 510 or equivalent sealing product.
Reinstall the "O" ring (J). Grease it lightly and Install it on the Powershift module. Sling the reverse shuttle and Powershift module assembly. Install the assembly in the unit housing. Lower the sling, aligning the centring pin (L) with the port.


Reinstall the screws (B) of the housing (D).

Removing the Powershift module
Remove the piston (57) and the springs (58).
Place the section with the reverse shuttle on a suitable supporting fixture, with the cover (26) and planet carrier (30) facing upwards.
Remove the planet carrier (30). To remove the planetary gears.
Take out the clutch O/brake N assembly from the cover (26). Retain the friction washer (69)Remove the clutch hub (61). Take out the screws (64) to remove the clutch cover (32).


Mark the order of the discs and brake/clutch thrust plates before removing them.
Mark the direction and remove the Belleville washers (67) and (68). If necessary, take out the needle bearing (73) of the clutch housing (66)Place the front part of the Powershift module facing downwards on a suitable supporting fixture. Make a mark (G) on the housings (28) and (18)Remove the screws from the housings (28) and (18), then remove the housing (28). Take out and discard the "O" rings (74) and (75) on the housing pilot ports. Discard "O" ring (19) and "O" ring (76).
Remove the ring gear carrier assembly (27), the two ring gears (29) and (65), with the front planet carrierRemove the circlip (46).
Separate the front planet carrier from the ring gearsRetain the spacer (45).
Remove the bearing (44), the washer (77) and the spacer (43) from the planet carrier (25). To remove the planetary gears.
Place the housing (18) on the shims, with the input shaft (10) facing upwards. Place service tool 3378012M2 on the input shaft (10) so as to protect the lip seal (11).
Unscrew the cover screws (2) of the housing (18). Remove the cover (2) and retain the springs (22). Discard the "O" ring (21).


Remove the brake piston (17) from the housing (18). Discard the "O" rings (23) and (24). Remove the friction washer (13). Remove the lip seal (11).
Remove the clutch M/brake L assembly from the housing (18).
Remove the friction washer (14) and the snap ring (42).


Place the clutch M/brake L assembly on a supporting fixture. Take out the screws (15) to remove the clutch cover (7).


If necessary, take out the snap ring (37) to separate the sun gear (36) from the clutch cover (7)Mark the order of the discs and brake/clutch thrust plates. Remove the discs (5) and thrust plates (6) of clutch M and the discs (8) and thrust plates (9) of brake LRemove the junction plate (16).
Mark the assembly order then remove the input shaft (10), the Belleville washer (4), the spring washer (72) and the bearing (12).

Install the Powershift module
Ensure all parts are in good condition. Ensure the clutch pilot ports and lubricating ports are clean.
Install a new oiled "O" ring (4) on the Powershift module cover (2).
In the cover (2), fit a new lip seal (11) smeared with grease on the inside and oiled on the outside.
Install the springs (22) in the housings. Install a disc (8) on the cover (2). If the brake discs or clutch discs have been replaced, they must be soaked for approximately one hour in a transmission oil bath.
Install the friction washer (13), with the grease removed and smeared with Loctite 648 or equivalent.
Install the Belleville washer (4), the ball bearing (12) and the spring washer (72) on the clutch housing (3). Slide on the shaft (10).
Install the junction plate (16), the clutch discs (5) and thrust plates (6), and a brake disc (8) and thrust
plate (9) on the clutch housing (3).
Reinstall the clutch cover (7). Install the screws (15) smeared with Loctite 242. Tighten to a torque of 33 Nm.
Install the snap ring (42) on the shaft (10). Install the friction washer (14) smeared with grease on the clutch housing (3).


Install service tool 3378012M2 on the input shaft (10) so as to protect the lip seal (11). Install clutch M /brake L on the cover (2), paying attention to the lip seal (11). Place the cover (2) on a supporting fixture to position the input shaft (10).
Replace the last disc (8) of brake L. Install the brake piston (17) with new, oiled "O" rings (23) (24), in the housing(18).
Reinstall the housing (18) on the cover (2). Install the cover screws smeared with Loctite 242. Tighten to a torque of 29-37 Nm.
Place the planet carrier (25) on the input shaft (10). Turn the planetary gears (48) to engage them with the sun gear (36) and line up the splines of the planet carrier on the shaft.
Insert the spacer (43,) which should be smeared with grease, and the ball bearing (44) in the planet carrier (25). Install the friction washer (77).


Position the ring gears (29) (65) and ring gear carrier (27) assembly on the planet carrier (25)Install the spacer (45) and the circlip (46).
Smear new "O" rings (76) and (19) with miscible grease and Install them on the housing (28)Using a sling, position housing (28) on housing (18). 
Make sure that the "O" rings are correctly positioned.
Install and tighten the housing screws (18) and (28), smeared with Loctite 242. Insert the brake piston (57), fitted with two new oiled "O" rings (55) (56), in the housing (28).
Install two shims in the housing (28) to hold the ring gears and the planet carrier in place during assembly of the module and the reverse shuttle.

Check that the needle bearing (73) is present in the clutch housing (66). Check its condition and change it if necessary.
Install the friction washer (69), smeared with grease, on the cover (26). Install a brake disc (33)Install the clutch housing (66) on the cover (26), followed by the hub (61), the Belleville washers (67) (68) and the junction plate (35)Install the clutch discs (63) and thrust plates (62). If the brake discs or clutch discs have been replaced, they must be soaked for approximately one hour in a transmission oil bath.
Install the brake discs (33) and thrust plates (34).
Install the clutch cover (32), the screws (64), smeared with Loctite 242, and tighten them to a torque of 33 Nm. Install the springs (58) in the cover (26).
Install the planet carrier (30) on the output shaft (47).
Reinstall the Powershift module on the reverse shuttle.

Disassembling and reassembling the planetary gears

The planetary gear pins are fitted already tightened in the thickest part of the planet carriers. The pins comprise lubricating ports that must be positioned facing the corresponding ports on the planet carrier.The disassembly principle is the same for all planet carriers. The following example applies to planetary gears in the front epicyclic gear train of the Powershift module.
Place the planet carrier (25) in a vice equipped with protective jaws.
Using a suitable press and fixture, drive out the pins (39) from the planet carrier (25), pushing from the side where the planet carrier is thickest.
Take out the planetary gear and retain the friction washers (41) and bearing needles (38).
Clean all the parts, check their condition and replace any that are defective.
Ensure the lubricating ports of the planet carriers and pins are clean. The pins of the planetary gears (39) are blocked by plugs (40). Check that the plugs are present. Install new ones if any are missing.
Prepare the planetary gears. Install the bearing needles in the planetary gears using miscible grease.
Place the planet carrier on a suitable supporting fixture. Install the planetary gear (48) with the needle bearing (38) and the two friction bearings (41).
Insert the pin (39), then drive it in, using a suitable press and fixture. Insert the pin until it is flush with the planet carrier surface.
Check that the planetary gears rotate freely.

Reinstall the PTO shaft (33).
Clean and check the condition of the gearbox hydraulic control unit.


Check for the presence of "O" rings in the hydraulic unit ports. If the "O" rings have to be replaced, oil them slightly. Apply Loctite 510 or an equivalent sealing product to the mating face of the unitReinstall the connecting pipes, then the hydraulic control unit. Install the screws.


Assemble the gearbox and the engine and rear axle.
Top up the transmission oil level. Carry out a clutch calibration procedure.
Carry out road tests to check the operation of the gearbox. Check the operation of the hydraulics and make sure that there are no leaks.