Hydraulic system - Open Centre Left-hand cover




The left-hand cover Installed to the centre housing acts as a support to the lift spool valve. On its external face, the cover is Installed with various channels:
- low pressure to the right-hand cover
- cooler and lubrication, to the gearbox
- high pressure to lift control system.
On its internal face, a reducer (1) maintains a pressure of approximately 5 bar to lubricate the braking mechanism in the trumpet housings. A version without hydraulic lift is available. In this case, a plate replaces the lift spool valve.

Removing and install 

Immobilise the tractor. Chock the front wheels. Take off the rear wheel concerned. Position a safety stand. Partially bleed the rear axle housing. Detach the fuel tank from the gearbox or, if necessary, remove it after draining.

Removal 

Mark and disconnect the harnesses:
- of the lift (1) and lower (2) solenoid valves,
- of the low pressure switch (17 bar) (12),
- of the temperature switch (7).
Mark, disconnect and block:
- the hose (15) from the steering spool valve (Orbitrol),
- the lubricating hose (14) to the cooler (hot oil),
- the hose (3) from the lift spool valve,
- the lift rams supply pipes (4),
- the lubricating pipe (13) to the gearbox (cold oil),
- the pipe (17 bar) (10) to the right-hand cover.
Disconnect the following controls:
- handbrake,
- Ground Speed PTO (8) (if fitted).
Disconnect the pipe (11) to the trumpet housing lubrication (all types). Take out the screws (5). Remove the support (6), support (9) (if mounted) and the cover.
If necessary, remove the transfer pipe (1).

Clean the mating faces of the housing and the cover.
Check that the O’rings of the transfer pipe (11) are not damaged and refit it on the right-hand cover.
Lightly smear the mating face of the housing with a sealing product (Loctite 510 or equivalent).
Screw two locally made guide studs “G” into opposing holes on the housing.

Reinstall
Reinstall the cover.
Install the handbrake control support (6) and the proportional PTO support (9) (if fitted) (Fig. 3). Take out the guide studs. Install and tighten the screws (5) to a torque of 72 - 96 Nm.
Reconnect the pipes, hoses and harnesses removed previously, according to their marks.
Attach the harnesses using one or more clip retainers. Check that they can move freely and easily. Use cables to connect the controls.

Check the control setting for:
- handbrake,
- Ground Speed PTO (if fitted).
Attach or reinstall the fuel tank.
Install the wheel. Remove the axle stand and trolley jack. Tighten nuts.
Top up the oil level in the rear axle and check it on the gauge located at the rear of the centre housing. Start the engine.
Check the operation of the lifting system and the oil tightness of the mating face, cover and hydraulic unions.