Bleeding the main brake system and trailer brake system

Bleeding the main brake system

Bleeding the main brake system is carried out as normal. Therefore, simply open the two bleed screws slightly and keep the two coupled brake pedals constantly and moderately depressed. In this configuration, the oil drains from the bleed screws only and under pressure.

Preliminary steps 
Remove the protective rubber caps (3) from the bleed screws (1) situated on the rear support of the auxiliary spool valves. Force-install the end of two locally obtained transparent pipes (T) onto each bleed screw to obtain a secure and efficient connection between the pipe and the bleed screw. This fitting precaution prevents the transparent pipe from coming loose from the bleed screw when bleeding the main brake system.

Carry out the following operations with the assistance of an operator:
- Start the engine and stabilise the engine speed at approximately 1300 rpm.
- Bring the oil up to operating temperature (optional).
- Open the two bleed screws by approximately one turn.
- Moderately depress the two brake pedals (coupled beforehand).
- Check that the oil under pressure is draining into each transparent pipe free of any air bubbles. When there are no longer any air bubbles, tighten the two bleed screws.

Operating test
Check the hardness under force of the brake pedals when coupled and uncoupled.
Move the tractor several metres at slow speed. At the same time, apply and release each brake pedal to carry out an initial operating test of the main brake system. Repeat the test with the pedals coupled.

Final steps
Check the tightness of the bleed screws and the hydraulic unions.
Reinstall the protective rubber caps onto the bleed screws.
Carry out a road test on the main brake system. If an operating problem occurs, check the electronic functions of the high-pressure braking unit and remedy any faults. If the problem persists, carry out the bleed operation a second time. If the problem still persists, switch off the engine and check the sealing of:
- the main brake system
- the high-pressure braking unit
- the high-pressure block/valves
- the brake piston seals located inside the rear axle centre housing.

Bleeding the trailer brake system

If the tractor is equipped with a trailer brake mechanism, it is strongly recommended to bleed the main brake and trailer brake systems simultaneously. To bleed the trailer brake system, use the same equipment, taking care to observe the following points:
- Open:
- the two bleed screws (1) of the main brakes;
- the trailer brake bleed screw (2).
This bleed screw is located on the outer priority block (16) of the hydraulic unit with two priority blocks (closed centre hydraulic system).
- When the bleeding is complete, tighten in the following order (optional):
- the left-hand brake bleed screw (1);
- the right-hand brake bleed screw (1);
- the trailer brake bleed screw (2).
- Check the trailer brake pressure on the quick coupling (4) located at the rear of the tractor (see chapter 9). If this pressure is not correct, eliminate any air entering in the system. Repeat the bleeding procedure.
- Carry out a road test.