Normal Duty trumpet housings GPA40 - trumpet housing assembly


The Normal Duty (ND) trumpet housings on tractors fitted with GTA1040 or GTA1540 transmission support the right and left-hand axle shafts. They contain the final drive units that transmit the rotation from the differential assembly. Tractors fitted with GTA1540 transmission may be fitted with trumpet housings with a flanged axle shaft or straight axle shaft.
The two trumpet housings are symmetrical. They are fitted either side of the centre housing.

Construction
The axle shaft (2) is supported by two tapered roller bearings (7) (8) and (12) (13) fitted opposite one another. External tightness is ensured via a three-lipped seal (5) and internal tightness by a single lip seal (11). The planet carrier assembly of the final drive unit (25) has three planet gears (22). It is splined to the axle shaft (2) in rotation. The shims (26) fitted at the end of the shaft allow for preloading of the tapered roller bearings. The final drive ring gear (15) is force fitted into the trumpet housing. It has five pins (14),which ensure the centring of the brake plate (30). Differential rotation is transmitted to the planet gears of the final drive via a sun gear shaft (29) on the teeth of which the brake disc (35) is fitted. The brakes are lubricated via a port O drilled in the trumpet housing.
On tractors fitted with GTA1540 transmission (50 kph), the brake discs (35) and plates (30) have a larger braking surface area.
On tractors fitted with GTA1540 transmission, the axle shaft (2) and planet carrier (25) are held in place by the tripod washer (27), the M20 screw (28) and the lock washer (1).
On tractors fitted with GTA1040 transmission, the axle shaft (2) and the planet carrier (25) are held in place by the tripod washer (27) and the M20 screw (28) smeared with Loctite.

Parts list - Tractors fitted with GTA1040 transmission 
(2) Flanged axle shaft (5) Three-lipped seal (6) Friction cage (7) Bearing cone (8) Bearing cup (9) Threaded plug (10) Trumpet housing (11) Single lip seal (12) Bearing cup (13) Bearing cone (14) Pins (15) Ring gear (16) Tab washer (17) Spacer (18) Screw (19) Circlip (20) Planet gear pins
(21) Washers (22) Planet gears (23) Needle rollers (24) Spacers (25) Planet carrier (26) Shim(s) (27) Tripod washer (28) M20 screw (29) Sun gear (30) Brake plate (35) Brake disc (36) Wheel stud
(39) Screw (40) Dowel (44) M16 stud, washers and nuts

Legend
A Grease chamber
B Details
D Silicone seal
E Imprint on planet gears
O Brake lubricating port

Parts list - Tractors fitted with GTA1540 transmission 
(1) Lock washer (2) Straight axle shaft (2) Flanged axle shaft (3) HNBR seal (5) Three-lipped seal (6) Friction cage (7) Bearing cone (8) Bearing cup (9) Threaded plug (10) Trumpet housing (11) Single lip seal (12) Bearing cup (13) Bearing cone (14) Pins (15) Ring gear (16) Tab washer
(17) Spacer (18) Screw (19) Circlip (20) Planet gear pins (21) Washers (22) Planet gears (23) Needle rollers (24) Spacers (25) Planet carrier (26) Shim(s) (27) Tripod washer (28) M20 screw (29) Sun gear (30) Brake plate (35) Brake disc (36) Wheel stud (39) Screw (40) Dowel (44) M16 stud, washers and nuts

Legend
A Grease chamber
E Imprint on planet gears
O Brake lubricating port

Removing and refitting the trumpet housing assembly

 Tractors fitted with GTA1040 transmission

Tractors fitted with GTA1540 transmission

Removal
Drain the centre housing.
Immobilise the tractor. If the tractor is not fitted with a ParkLock device, engage the hand brake. Chock between the frame and the front axle.
Remove the wheel concerned. Place an axle stand in position.
Visually anticipate the separation of the trumpet housing from the centre housing, checking that the trumpet housing and cab will not obstruct each other. If this is not the case, proceed as follows:
- Unscrew the cab attachment screws on the trumpet housing support.
- Raise the rear of the cab slightly until the trumpet housing separates from the centre housing.
- Chock the cab.
Remove:
- the stabilising support;
- the lower pivot pin of the lift ram.
If necessary, remove the guard (draft sensor harness) from the trumpet housing. Support the trumpet housing with a suitable fixture and a trolley jack or a hydraulic table.
Remove:
- the screws (39);
- the nuts screwed to the M16 studs (44);
- the washers.
Split the trumpet housing assembly from the centre housing.
Remove:
- the brake disc (35);
- the sun gear (29);
- the dowel (40) (if necessary);
- the brake plate (30).

Refitting
Tractors fitted with GTA1040 transmission
Clean the mating faces of the trumpet housing and centre housing with solvent. Remove all traces of the previous sealing product. Dry the components. Evenly smear the mating face of the trumpet housing (10) against the centre housing with a sealing product (Loctite 5206 or equivalent).


Evenly fill angle D of the centre housing (1) with a silicone seal (Loctite 5910 or equivalent). The diameter of the seal must be:
- uniform;
- of small section.
The seal must not have gaps. The join must be located at the top of the centre housing.
On the trumpet housing, refit the brake plate (30), applying three spots of miscible grease to ensure that it sticks to the ring gear (15).
On the centre housing, refit the dowel (if removed).


On the trumpet housing or the centre housing (as required), refit the sun gear (29) and the brake disc (35). Ensure that the latter slides freely on the sun gear splines.

Tractors fitted with GTA1540 transmission
Clean the mating faces of the trumpet housing and centre housing with solvent. Check that the groove of the seal on the centre housing is free of dirt. Dry the components.


Fit a new HNBR seal (3) to service tool.
The HNBR seal (3) has no spurs P. Do not confuse it with the NBR seal (4). These two seals are not exposed to the same temperatures when the transmission is operating (e.g. the HNBR seal (3) is exposed to higher temperatures when the brake is engaged). Their components are therefore different and they must be fitted correctly in their respective positions.
Attach the tool fitted with the HNBR seal (3) to the centre housing. Manually exert high pressure around the tool while simultaneously turning it so that the seal fits correctly into the groove of the centre housing (1). It is strongly recommended that the HNBR seal (3) is fitted using the service tool.


Fitting it without the tool will stretch the seal and cause a loop to form in the final assembly phase. Remove the service tool. Ensure the HNBR seal (3) is positioned correctly on the centre housing. Apply three spots of miscible grease to the relevant mating face of the brake plate (30) and stick the plate against the ring gear (15) of the trumpet housing. The brake plates (30) on tractors fitted with GTA 1540 transmission (50 kph) have a notch E, which must be positioned facing upwards.


Tractors fitted with GTA1540 transmission (50 kph) are assisted by a return travel limit mechanism on the brake pistons. As a result, before replacing the brake plates (30), it is advisable to push the brake pistons fully into their cavity so that this return travel limit mechanism once again returns the brake pistons correctly after the operation.
On the centre housing, refit the dowel (if removed).
On the trumpet housing or the centre housing (as required), refit the sun gear (29) and the brake disc (35). Ensure that the latter slides freely on the sun gear splines. Tractors fitted with GTA1540 transmission (50 kph) are assisted by a return travel limit mechanism on the brake pistons. As a result, before replacing the brake discs (35), it is advisable to push the brake pistons fully into their cavity so that this return travel limit mechanism once again returns the brake pistons correctly after the operation.

Tractors fitted with GTA1040 or GTA1540 transmission
Support the trumpet housing using the equipment used for removal. Engage the splines of the sun gear (29) in the differential or planet carrier (as required). If they do not engage, rotate the axle shaft and push the trumpet housing horizontally to couple it with the centre housing.
Tighten:
- the M16 screws (39) to 220-300 Nm;
- the M16 nuts (44) to 220-280 Nm.
If required, refit the guard (draft sensor harness).
Refit:
- the lower pivot pin of the lift ram;
- the stabilising support.
If it was necessary to lift the cab, reposition it on the trumpet housing support(s). Screw in the cab attachment screws.
Refit any parts removed from around the trumpet housing.
Refit the wheel. Tighten the screws and nuts to their indicated torque, depending on the version. Top up the centre housing oil level. Check it using the sight glass located to the left of the PTO housing.
Remove the shims between the frame and the front axle.
Check the linkage operation. Carry out a road test on the brake system.
Check the tightness of the trumpet housing, the hydraulic unions and the plugs.