Ground Speed PTO GPA40 - Disassembly and reassembly the gears


The GSPTO comprises a driving gear train (17) (33) and a driven gear train (27) (10) located respectively at the front and rear of the centre housing.
If work is necessary on the driving gear train (17) (33), proceed as follows:
• To access the gear (17) (GTA1040 and GTA1540 transmission (40 kph only))
- Disconnect the tractor between the gearbox and the centre housing.
- Remove the gear (17).
• To access the gear (33) (GTA1040 transmission)
- Remove the 4WD clutch unit.
• To access the gear (33) (GTA1540 transmission (40 kph only))
- Disconnect the tractor between the gearbox and the centre housing.
- Remove the 4WD clutch unit.
If work is necessary on the driven gear train (27) (10) (all types of transmission except GTA1540 (50 kph)), remove the rear PTO housing. The lower bearing and removable support S are also removed with this housing during the operation.


Disconnect the PTO housing from the centre housing.

Disassembly 
Place the housing in a horizontal position with the gears facing upwards as required. Loosen the nut (16) and the pushrod screw (15) for the 540 - 1000 rpm selector rail. Remove the ground speed PTO selection mechanism.
Loosen the countersunk screw (21). Recover the chamfered washer (22).


Remove the splined sleeve (6). Unlock the nut (25).
Immobilise the output shaft using a locally obtained M16 screw. Partially loosen the nut (25) using a standard socket (55 mm flat). The nut (25) must be unlocked before removing removable support S in order to take advantage of the opportunity to lock the output shaft (13) with the M16 screw.
Remove removable support S using bearings at the front ends of the PTO shafts (upper and lower). Finish unscrewing the nut (25) and remove it.

Also remove:
- the hub (29) and the coupler (31);
- the bearing cone (18) (to be paired with the cup (19) if it is to be re-used);
- the shims (20);
- the bearing cone (11) (to be paired with the cup (30) if it is to be re-used);
- the gear/shaft assembly (27).


Drive out the bearing cups (19) (30) from the removable support.
If necessary, visually note the position of the shaft (8) and remove it along with the sleeve (26). Remove the circlip (3). The undercut end of the shaft (8) is positioned towards the 4WD clutch unit.
If necessary, remove the driven gear (10), which is centred and fitted to the 540 rpm gear (7) via a screw. The method of fitting one gear against another has already been used in chapter 7 in the section on the GPA40 output shaft and brake).


Strip the sleeve (6) by carrying out the following steps:
- Remove the circlip (24).
- Drive out the ball bearing (23).

Reassembly
Clean and check all components. Replace those that are defective.
Assemble the sleeve by carrying out the following steps:
- Install the ball bearing (23) using a suitable fitting drift whose external diameter should be slightly less than the external diameter of the ball bearing.
- Install the circlip (24).
If necessary, reinstall:
- the driven gear (10);
- the circlip (3) in the sleeve (26);
- the shaft (8).
Install the bearing cups (19) (30) against the removable support cord.
Shim the bearings (11) (30) and (18) (19) of the gear/shaft assembly (27).
Install the removable support. Tighten the V screws to a torque of 68-92 Nm.
Clean the threads of the new nut (25) and the gear pin (27).
Lightly smear the nut thread with Loctite 270 or equivalent.
Immobilise the output shaft.
Correctly position the nut. Definitively tighten to 160-240 Nm.
Using a suitable punch, lock the nut in place by bending the collar into the grooves of the shaft without breaking it.
Reinstall the coupler (31) and the splined sleeve (6). Correctly position the chamfered washer (22) and install it to the ball bearing (23). Lightly smear the thread of the countersunk screw (21) with Loctite 270 or equivalent. Tighten this screw to a torque of 24-28 Nm.
Reinstall and adjust the ground speed PTO selection mechanism.
Install the pushrod screw (15) and the nut (16) of the 540 - 1000 rpm selector rail. Adjust the pushrod screw. Reconnect the PTO housing to the centre housing. Start the tractor engine and check the GSPTO operation.

Shimming the gear/shaft assembly bearings

The gear/shaft assembly (27) is shimmed with removable support S. The removable support must be removed from the rear PTO housing assembly and clamped in a vice fitted with protective jaws.

Preparing for shimming 
Assemble the gear/shaft assembly (27) with the bearing cones (11) (18) lightly lubricated. Separate the bearing cones by a shim (20) thickness in order to obtain a temporary clearance of approx. 0.10 to 0.15 mm.
Install the hub (29).
Immobilise the gear/shaft assembly (27) using a makeshift tool. Temporarily tighten the nut (25) to 30 - 50 Nm with no Loctite on its thread.

Shimming 
Place the feeler pin of a dial gauge on the end of the gear/shaft assembly (27).
Using the appropriate levers, apply diametrically opposed pressure on the gear of the gear/shaft assembly (27) by pulling on this assembly in order to fit the cone (18) in its bearing cup.
With the help of an operator, set the dial gauge needle to zero.
Repeat, pulling on the hub (29) in order to Install the cone (11) in its bearing cup.
According to the temporary clearance reading measured on the dial gauge, determine another shim (20) thickness to obtain a preload P1 = 0.05 to 0.15 mm. As far as possible, shim to the maximum
tolerance. Loosen and remove the nut. Remove the hub (29) and the bearing cone (18). Install the shims between the two bearing cones (11) (18).
Reinstall the hub. Lock the nut (25) again to a torque of 30-50 Nm, with no Loctite on its thread, in order to manually check the rotation of the gear.

Assembling and adjusting the control

Parts list 
(1) Lever (2) Clevises (4) Cable (5) Support (6) Switch (7) Stops (8) Pin (9) Clips (10) Connecting rod

Install the control, lever side 
Preparing the cable
If possible, tighten the clevis (2) to the maximum against the cable (4). Tighten the nut (3).
Assembly
Link the clevis to the lever (1) using the clip (9).
Tighten the sheath end to the support (5) using nuts (11).


Install and adjusting the control, centre housing side 
Preparing the cable
If possible, tighten the clevis (2) to the maximum against the cable (4). Tighten the nut (3).
Assembly
Slide the sheath end of the cable onto the support fitted to the right of the housing assembly.
Place the lever (1) and the rod (10) in GSPTO position.
Connect the clevis (2) to the rod (10) using the clip (9).
Settings
Adjust the sheath end on the support using the nuts (11) and without moving the rod (10). Tighten the nuts.


Check that the control moves freely in each position (neutral and engaged). The coupler (31) has spur cut teeth: it can only be controlled if the tractor is almost stationary.