GPA40 rear PTO - Output shaft and brake


On tractors equipped with GTA1040 or GTA1540 transmission, the rear PTO may be installed with a 540 E economy version. The economy version follows the principle of the 540 - 1000 rpm standard equipment and is produced by fitting an additional 540 E gear (10) centred and fitted to the 540 rpm gear (7) via a screw (11). The profile of the 1000 rpm driven gear differs according to the transmission type and equipment installed:
- detail A: GTA1040 and GTA1540 tractor transmission without Power Boost PTO;
- detail B: GTA1540 tractor transmission with Power Boost PTO.


The profile of the 1000 rpm driving gear also differs according to the transmission type and equipment fitted. Regardless of the type of PTO, the driven gears are constantly meshed with the driving gears driven by the upper shaftline. The output shaft (13) is fitted on tapered roller bearings (3) (8) and (19) (21) mounted respectively in the rear PTO housing and in the removable front support (12).


The 540-1000 rpm gears (7) (18) are splined to the output shaft and clamped between the bearing cones by the nut (2). The rear bearing is sealed by the seal (14). The preload of the tapered roller bearings is adjusted by using the shims (23) inserted between the removable front support (12) and the bearing cup (19). Sensor C (if fitted) located to the right of the PTO housing informs the tractor's electronic system of the speed of the output shaft via the 540 rpm driven gear. A threaded plug C blocks the sensor port if the sensor is not fitted. The rear PTO brake is a cylindrical piston (25) fitted with an "O" ring (17). This piston is housed in a bore of the rear PTO housing. When the PTO clutch supply is interrupted, the 17 or 21 bar pressure is applied to the brake. The piston then travels towards the machined face of the 1000 rpm driven gear (18) and compresses this gear via a friction washer (26) in order to gradually slow down the rotation of the mechanical sections of the PTO until they are completely immobilised.

Lubrication 


The lower shaftline of the PTO is lubricated by a pipe (5) which carries transmission oil to the axial port and the radial holes in the output shaft (13). The oil lubricates the splines on the 540-1000 rpm gears and the rear bearing (8) (21). The front bearing (3) (19) is lubricated by oil splashing from the gears as they move.


Parts list 
(1) Screw (2) Undercut nut (3) Bearing cone (4) Long or short flanged shaft (interchangeable shaft) (5) Lubrication pipe (6) Screw (7) 540 rpm driven gear (8) Bearing cone (9) Guard (10) 540 E driven gear (11) Screw (12) Removable front support (13) Output shaft (14) Seal (18) 1000 rpm driven gear (19) Bearing cup (21) Bearing cup (23) Shims (24) "O" ring
Legend
A Details
540 - 1000 rpm PTO
540 E PTO



Disassembling and reassembling the 540 - 1000 rpm or 540 E driven gears, tapered roller bearings and seal

Disconnect the PTO housing from the centre housing. All operations on the PTO lower shaftline, including removal of the rear bearing gasket, involves removing and install the PTO housing.
Only the flanged shaft (4) can be disassembled without having to carry out this removal operation. Remove the sensor (if fitted) located to the right of the rear housing of the PTO.
Remove the 540 - 1000 rpm (2-speed) or 540 E (3-speed) PTO selection mechanism and the front removable support (12).

Disassembling the 540 - 1000 rpm driven gears 
Immobilise the output shaft (13) by inserting a locally obtained M16 screw into hole T located between the rim of the output shaft and the rear housing of the PTO.
Unlock the nut (2) and loosen it using a standard socket (55 mm flat).
Extract the bearing cone (3). Remove the 540 - 1000 rpm driven gears (7) (18) from the rear housing of the PTO.
Using a soft hammer, tap the inside end of the output shaft and drive the output shaft outwards. Recover the bearing cone (8). Drive out the bearing cup (21). Drive out the seal (14) from the rear housing of the PTO. Discard it.


Reassembling the 540 - 1000 rpm driven gears
Correctly position the new seal (14) in the rear housing of the PTO. Using tool ref. 3378115M1, gradually Install the new seal at a distance of 240 mm from the face of the rear housing of the PTO (figur detail A).
Install the bearing cup (21).
Lubricate the mating face of the seal (14) on the output shaft with clean transmission oil.
Engage the output shaft in the port on the rear housing of the PTO. Install the bearing cone (8) on the output shaft using a suitable locally obtained fitting drift.
If necessary, shim the tapered roller bearings (3) (19) and (8) (21).
Reinstall:
- the driving gears;
- the 540 - 1000 rpm driven gears (7) (18).
Using a suitable fixture, Install the bearing cone (3).
Clean the threads of the new screw (2) and the output shaft (13).
Lightly smear the thread of the nut with Loctite 270 or equivalent. Screw this nut onto the output shaft. Immobilise the output shaft.
Definitively tighten the nut to 160-240 Nm.
Using a suitable punch, lock the nut in place by bending the collar into the grooves of the output shaft without breaking it.

Disassembling the 540 E driven gears 
Immobilise the output shaft (13) by inserting a locally obtained M16 screw into hole T located between the rim of the output shaft and the rear housing of the PTO.
Unlock the nut (2) and loosen it using a standard socket (55 mm flat).
Extract the bearing cone (3). Remove the 540 E driven gears (7) (10) from the rear housing of the rear PTO. Turn the 540 E gear set over in order to access the screw heads (11) (detail B). Then slide the overturned 540 E gear set onto the output shaft (13). Immobilise the output shaft. Unscrew the screws (11).
Remove the 540 E gear set from the rear housing of the PTO again and separate it. Using a soft hammer, tap the inside end of the output shaft and drive the output shaft outwards. Recover the bearing cone (8). Drive out the bearing cup (21). Drive out the seal (14) from the rear housing of the PTO. Discard it.


Reassembling the 540 E driven gears
Correctly position the new seal (14) in the rear housing of the PTO. Using tool ref. 3378115M1, gradually Install the new seal at a distance of 240 mm from the face of the rear housing of the PTO (detail A).
Install the bearing cup (21).
Lubricate the mating face of the seal (14) on the output shaft with clean transmission oil.
Engage the output shaft in the port on the rear housing of the PTO. Install the bearing cone (8) on the output shaft using a suitable locally obtained fitting drift.
Clean the tapped holes on the gear (10) and the screw (11) threads.
Reassemble the 540 E gear set (7) (10).
Lightly smear the thread of the screws (11) with Loctite 270 or equivalent. Screw in and tighten these screws to 110-140 Nm.
If necessary, shim the tapered roller bearings (3) (19) and (8) (21).
Reinstall:
- the driving gears;
- the 540 E driven gears.
Using a suitable fixture, fit the bearing cone (3).
Clean the threads of the new screw (2) and the output shaft (13).
Lightly smear the thread of the nut with Loctite 270 or equivalent. Screw this nut onto the output shaft. Immobilise the output shaft.
Definitively tighten the nut to 160-240 Nm.
Using a suitable punch, lock the nut in place by bending the collar into the grooves of the output shaft without breaking it.

Install the 540 - 1000 rpm (2-speed) or 540 E (3-speed) PTO mechanism and the front removable support (12).
If necessary and depending on the option, Install the sensor located to the right of the rear PTO housing. During the refitting process:
- lightly smear the sensor thread with Loctite Form A Gasket 2 or equivalent;
- tighten home the sensor, without forcing, until its end is positioned against the gear (7),
- unscrew the sensor by three quarters of a turn;
- moderately tighten the nut.
Reconnect the PTO housing to the centre housing.
Start the tractor engine and check the PTO operation.

Shimming the output shaft


540 - 1000 rpm PTO


540 E PTO

Preparation for shimming (depending on version)
Temporarily reassemble the lower PTO shaftline in the rear housing with the output shaft (13), the lubricated bearings and the driven gears. To reduce the inertia caused by the gears during the alternating movement (right/left) from the output shaft during the shimming operation, it is advisable to temporarily remove the driving gears from the upper shaftline.
Tighten the nut (2) to 160-240 Nm without Loctite.
In space E of the removable front support (12), slide a shim (23) thickness reduced from 0.15 to a maximum of 0.20 mm in relation to the thickness found during disassembly. Install the bearing cup (19).
Temporarily fix the removable front support (12) to the rear housing of the PTO. Tighten a few opposing V screws to 68-92 Nm.

Shimming (depending on version)
If necessary, to obtain a smooth area for the dial gauge feeler pin contact, gently surface the rear end of the output shaft (13) using an oilstone.
Install the dial gauge feeler pin to the end of the output shaft.
Push firmly on the output shaft, turning it alternately to the right and left in order to correctly fit the cones in the bearing cups.
Set the dial gauge to zero.
According to the temporary clearance reading measured on the dial gauge, determine another shim (23) thickness to obtain a preload P1 = 0 to 0.10 mm. As far as possible, shim to the maximum tolerance.

Disassembling and reassembling the rear PTO brake


Remove the 540 - 1000 rpm or 540 E driven gears (depending on version).
Remove the friction washer (26) (bi-metal).
Using a jet of compressed air, carefully drive out the brake piston (25) from the rear housing of the
PTO. Remove the "O" ring (27). Discard it.
Clean the hydraulic chamber of the brake piston (25). Check that there is no dirt inside the 17 or 21 bar channel.
Install a new "O" ring (17) in the brake piston (25) groove.
Install the brake piston fitted with its "O" ring in the rear housing of the PTO, positioning its chamfered edge towards the hydraulic chamber. The chamfer provides a correct hydraulic supply to the brake piston.
Refit the friction washer (26) (bi-metal) to the brake piston, positioning its ribbed face towards the driven gear (18). The lubrication between the brake piston and the friction washer is provided by splashing caused by the moving parts.
Reinstall the 540 - 1000 rpm or 540 E driven gears (depending on version).


Replacing the interchangeable shaft or flanged shaft


If it is necessary to remove and reinstall the interchangeable shaft (4), proceed as follows.
Immobilise the output shaft (13) by inserting a locally obtained V M16 screw in hole T.
Unscrew the screws (6). Remove the interchangeable shaft (4).
Check that the dowel (28) is present. Install the interchangeable shaft.
Screw in the screws. Tighten to a torque of 120-140 Nm, immobilising the output shaft (13).