Universal joint shaft brake

On some model tractors, the universal joint shaft brake comprises 6 discs and 6 intermediate plates, distributed on either side of a mechanism and activated by a control piston and a pin. The control piston is located on the right-hand side of the gearbox. The brake piston pushes the control rod, which activates

the brake plate. This then moves apart, and compresses the discs against the intermediate plates, which are splined together by pins (14). When released, the control plate springs ensure minimum clearance between the brake discs. Lubrication is ensured by an external hydraulic pipe coming from the lubricating circuit.

Exploded view of the universal joint shaft brake 

1 Shaft

3 Flange

4 Dowel pin

5 Allen screw

7 Brake plate

8 Ball

9 Spring

10 Dowel pin

12 Intermediate plate

14 pin

16 Universal joint shaft brake control piston

17 Control rod

22 Seal

23 Cylindrical screw

25 Stud

26 Nut

Cross-section view of the universal joint shaft Brake 

Disassembling the universal joint shaft brake

The following operations must first be carried out: Drain the transmission oil (approx. 65 litres). Split the tractor between the clutch housing and transmission housing. Remove the universal joint shaft. For easier reading, the work is carried out on a scale model. References are relative to figure.

Remove the suction filter of the variable displacement pump, if it obstructs disassembly (depending on model). Take off the internal leak pipe and deflector. Remove the lubricating oil pipe. Remove the control piston of the universal joint shaft brake (16). Take off the sleeve.

Remove the screws from the flange (5). Push out the flange (3) with two M8 screws. When pushing out the flange, the drive shaft must not leave its seat.

Take off the flange (3), discs (11), intermediate plates (12) and brake plate (7).

Reassembling the universal joint shaft brake

Before reassembly, all components, mating faces and grooves must be clean. Any rust, mud or water must be removed. Fit the studs (4).

Starting with an intermediate plate (12), fit 3 intermediate plates (12) and three discs (11) alternately. The first intermediate plate is fitted in position A. Use new intermediate plates (12) and new discs (11). Oil the discs before assembly.

The second intermediate plate is fitted in position B, and so on alternately.

Fit the brake plate (7). The control pin must be opposite the drilled hole.

Fit the control piston of the brake (16) with a new seal (22). Assemble the activating corner correctly as shown on the brake plate (7). Fit the remaining discs (11) and intermediate plates (12). Clean the mating face of the cover and smear with sealing product (ref. X 903.050.074).

Fit the flange (3) and tighten the screws (5) to a torque of: 50Nm

Check the axial clearance of the universal joint shaft with a dial gauge.

Specified value: 0.3 + 0.1mm

If outside the specified value, correct the clearance with compensating shims.

Fit the lubricating pipe, return pipe and deflector. Fit a new suction filter.

Grease and install a new O�ring. Insert the sleeve on the shaft (1).

Adjusting the brake control piston:

Unscrew the locknut. Tighten the adjustment rod with a torque wrench (or the corresponding torque gauge, ref. X 899.980.151); to a torque of: 4 to 5Nm

Unscrew the rod by 3.6 turns and lock it in this position. Assemble the tractor between the clutch housing and transmission housing. Refit the universal joint shaft. Fill up the transmission oil.

Disassembling the universal joint shaft brake control

Remove the hydraulic pipe. Loosen and remove the brake cylinder attachment screws. Remove the brake cylinder and control rod. Discard the paper gasket.

Reassembling the universal joint shaft brake control

Clean the mating faces of the gearbox and brake cylinder. Smear the control lever ball joint with miscible grease. Fit the control rod in the brake cylinder.

Oil and fit a new paper gasket. Fit the control rod / brake cylinder assembly in the gearbox housing. Fit and tighten the brake cylinder attachment screws.

Reconnect the hydraulic pipe. Bleed the brake.