Removing and install auxiliary spool valves


Auxiliary spool valves can be removed and refitted directly on the tractor by removing each unit and leaving only the main support fitted to the lift cover.

Preliminary operations

Remove unit(s) close to the auxiliary spool valves which might obstruct access to them. (Example: hydraulic valve for automatic hook).

Disconnect:
- the supply hose (3) from the right-hand hydraulic cover;
- the outlet hose (2) to the lift control spool valve.
Separate the control cables of the supports and spool valves.

Removal
Remove the locknuts (1) located at the end of the spool valve set.

Release and remove each hydraulic component after visually noting its position. The spool valves are fitted either side of the main support.

If necessary:
- Remove quick-disconnect couplings (A) and (B).
- Remove pins (1) and screws (2). Separate the cable support (3) from the spool valve.


Install
Reinstalling operations are not difficult. They therefore require carrying out the removal operations in reverse order. However, during refitting it is necessary to ensure that:
- parts to be assembled are not dirty, corroded, dented, etc.
- seals are oiled.
The locknuts fitted at the end of the spool valve set should be tightened to a torque of 30 - 33 Nm.

Check the correct operation of each spool valve on the two, three or four positions (depending on model).
Check the pressure on quick-disconnect couplings.

3-position spool valve, SA / DA with spring loaded return to neutral

Operation 
Oil from the high flow rate circuit passes through the trailer braking valve (3) (if fitted) or closing plate fitted to the right-hand hydraulic cover and supplies the various spool valves via the continuity channel (N). The spool valves are fitted in series in priority over the linkage.


Neutral position 
Oil is not available from outlets (A) or (B). Oil is directed via the continuity channel (N) to the lift control valve and passes directly to the suction manifold of the pump when the linkage is in neutral position.
Channels (N) and (P) are linked in the intermediate block to supply the subsequent spool valves.


Inlet - outlet position 
When the spool (2) is moved upwards or downwards, the continuity channel is cut, the pressure increases and raises the valve (1). The oil is then directed to the internal channels via grooves located on the spool. Depending on the spool position, outlets (A) or (B) are supplied. Simultaneously, the oil returning from the ram is directed depending on the position of the spool, to outlets (A) or (B) to reach the return channel (R).

Single / double acting change-over 
To obtain the single acting position, unscrew the valve (4). The outlet (A) then opens into the channel (R), and the outlet (B) supplies the hydraulic slave device. To obtain the double acting position, screw in the
valve (4).

3-position spool valve, SA / DA with automatic return to neutral

Neutral position
The operating principle of the 3-position single or double acting spool valve with automatic return to neutral, is the same as for the previous 3-position SA / DA spool valve with spring loaded return to neutral.


Inlet - outlet position 
Operation is identical to the 3-position SA / DA spool valve with spring loaded return to neutral, with automatic return to neutral as an added feature. A system placed in the unit (1) locks when the spool (2) is activated. The spool returns automatically when the pressure reaches 150 - 170 bar. The pressure passes through bores machined in the spool. It then releases a system comprised of balls and springs allowing the automatic return of the spool to neutral. The unit (1) is joined to channel (R). A residual pressure in the unit (greater than 2 bar) may cause undue return of the spool to neutral.

3-position SA / DA spool valve with non-return valve and automatic return

The operation of this spool valve is identical to those explained previously.


Operation of the non-return valve 
When the spool (2) is moved upwards, the oil coming from channels (N) and (P) is directed to outlet (B) by lifting the non-return valve (3) which supplies the slave device. In the neutral position, the non-return valve ensures the oil tightness of the circuit. When the spool is moved upwards, the oil coming from the channels (N) and (P) lifts the valve (1). It is then directed to an internal channel via grooves machined on the spool, and supplies the slave device via the outlet (A). The movement of the spool shifts the pushrod (4). This raises the ball, causing a drop in pressure on the slave device side, which allows the valve (3) to rise from its seat and oil to flow through to the channel (R). During disassembly of the spool (2), it is essential to first disassemble the non-return valve (3) and pushrod (4).

4-position DA spool valve, with automatic return to neutral and floating position


Operation 
When the spool (2) is moved upwards or downwards, the same positions are obtained as in the previous spool valves. The 4-position DA spool valve with automatic return to neutral and floating position has an added feature: a floating position (F) when the spool has moved its maximum distance out of the automatic return to neutral position. In this position (F), the outlet channels (A) and (B) open into the return channel (R). The oil then circulates freely.



Assembling and adjusting a control cable

Cab side
• The numbers (1) to (3) indicate the location of the levers on the console.


• The console design allows the assembly of a fourth spool valve.
The control unit (1) is designed to incorporate the lever and cable.


After assembling the unit, move the control lever to neutral position.

Spool valve side 

Special points 

• If a stirrup (4) needs to be replaced, remove and replace it without turning the spool (2) of the spool valve.

• When assembling, the pins (3) should be lightly smeared with molybdenum disulfide or AS767 grease or equivalent.

Screw the clevis (1) to the threaded part of the cable (2).

Attach the clevis to the stirrup (4) using the hook (3). Tighten nut.

Adjust the stop (5) with the nut (6).

Tighten nut (7) and check that the cable is not constrained in any way.




Check
Start the tractor engine. Using the relevant lever (2), check that the three or four positions of the spool valve (depending on model) engage correctly. 


In case of faulty operation, separate the spool valve control and check the movement of the spool. If it operates correctly, check the cable adjustment again.