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Disassembly and assembly the Orbitrol
If the Massey Ferguson 6465, 6490, 6495 Tractor Orbitrol steering unit
is defective, take care that it is replaced with a unit with exactly the
same characteristics.
OSPC 150 ON spool valve
OSP = Orbitrol steering pump
C = Valves incorporated in the steering unit
150 = 150 cm3 per rotor revolution
ON = Open centre without feedback
- Remove the spool valve from the Massey Ferguson 6465, 6490, 6495
Tractor and tighten it in a clamp with soft jaws.
- Remove the jaws if necessary. Take out the screws. Split the manifold
from the spool valve. Collect the seals.
- Take out the screws. Carefully mark the location of the screw and then
remove it.
- Remove the closing plate, O'ring, stator and O'ring. Remove the
spacer, the rotor, the distributor plate and the O'ring.
- Take out the splined link shaft. Unscrew the threaded ring and take
out the valve ball from the non-return valve.
- Take out the two pins and valve balls from the suction valves of the
MF 6465, 6490, 6495 steering unit.
- Extract the sleeve and spool valve assembly by pushing it out while
checking that the pin lies along the horizontal axis.
- Remove the washers, the needle bearing and the bush from the sleeve /
spool valve assembly. Remove the pin, and the centring springs by
pressing on their ends.
- Separate the sleeve from the spool valve.
- Unscrew the plug from the relief valve. Using an 8mm Allen wrench,
disassemble the threaded bush and remove the seal, the spring and the
valve (the crimped seat cannot be removed).
- Unscrew the two plugs from the shock valves. Remove seals. Using a 6mm
Allen wrench, remove the threaded bushes and take out the springs, the
valve balls and their seats (the crimped seats cannot be removed).
- Extract the seal, the bush and the O'ring. Disassemble the non-return
valve.
- Check and clean the components. Replace any defective parts. Lubricate
with clean transmission oil before reassembly.
- Reassemble the non-return valve. Install the seal, the O'ring and the
ring.
- Place the valve balls and springs in the recesses of the shock valves.
Screw on the threaded bushes. Fit the seals and tighten the plugs.
- Install the valve and spring in the recesses of the relief valve.
Screw in the threaded bush. Fit the seal and tighten the plug to a
torque of 40-60 Nm.
- Insert the spool valve into the sleeve. Position the centring springs
and insert the pin.
- Position the bush on the sleeve and spool valve assembly so that the
chamfer facilitates assembly in the steering unit.
- Place the washers, the chamfer of washer towards the centring springs,
by inserting the needle bearing between them.
- Install the Massey Ferguson 6490, 6495, 6465 Tractor sleeve and spool
valve assembly in the steering unit by oscillating it slightly. Check
that the pin is held horizontally.
- Place the two valve balls and the two pins in the recesses of the
suction valves.
- Install the valve ball in the non-return valve recess. Screw in the
threaded bush.
- Position the splined link shaft. Install the O'ring and the
distributor plate.
- Install the rotor so that the two concave depressions lie along the
axis of the slot in the splined link shaft. Install the spacer. Place
the O'rings on the stator.
- While avoiding moving the rotor, fit the stator. Then move it so that
its fixing holes match with those of the steering unit. Install the
closing plate.
Replace the seals and fit:
- the screw (in the positions marked during disassembly);
- the opposing screws tightened to 30-35 Nm;
- the manifold on the steering unit (screws tightened to 60 Nm);
- the sleeves on the manifold.
Using a test-bench or a suitable fixture, check the adjustment and
correct operation of the steering unit. Install the steering unit on the
tractor.
Removing and install the MF 6490,
6465, 6495 Tractor steering Ram
- The general procedure is similar on fixed or suspended front axles.
- Immobilise the tractor. Chock the rear wheels. Apply the handbrake.
- To help release the steering ram from its overlap flange, first remove
the front left-hand wheel and mudguard (if fitted).
- Remove the locknuts and drive ou the steering pivot balls using a
suitable extractor tool.
- Loosen nut. Remove the right-hand steering link rod (including pivot
ball).
- Disconnect and block the supply hoses (right and left) from the ram,
marking their positioning.
- Take out the screws and remove the ram. Install the steering ram.
Tighten the screws to a torque of 120 Nm.
- Reconnect the left-hand and right-hand supply hoses of the ram.
Install the link rod and steering pivot balls.
- Reassemble the wheel(s). Tighten the nuts and screws to their
indicated torque, depending on version. Adjust wheel alignment.
Complete the operation by tightening:
- steering pivot ball nuts to a torque of 220 Nm;
- steering link rod nuts.
Disassembling and reassembling
operations
Fig.25,26. The Massey Ferguson MF 6465, 6490, 6495 Tractor
steering ram assembly (1) comprises the following parts
(2) Pack of seals (4) Cylinder (6) Piston pin (7) Cover
- Release and remove the ball joints (7).
- Separate the cover (7) from the cylinder (4).
- Take out the piston (6) from cylinder.
- Discard all the seals (sealing ring, O'rings and dust seal).
- Ensure that the internal bore of the cylinder and the operational
parts of the piston rod are free of scratches: scratches can cause leaks
in the steering unit.
- Lubricate the seals, bushes and cylinder internal bore with clean
transmission oil.
- Install the seals on the piston rod (6) cylinder (4) and the cover (7)
respectively.
Put together the MF 6465, 6490, 6495 Tractor
steering ram without damaging the oil tight seals:
- slide the piston rod fitted with its seals in the cylinder bore;
- put the cover back on the cylinder, with the pressure inlet facing the
right direction.
- Tighten and lock the ball joints (7) to the torque of 300 Nm. Install
the steering ram on the tractor.
- Check the hydraulic pressure on the cylinder line. Carry out a road
test on the steering system.
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