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Massey Ferguson 8260 hydraulic system - Lift control spool valve with Rexroth auxiliary spool valves
The Massey Ferguson 8260 lift control spool valve is fixed to a manifold provided with three drilled channels. It is mounted on the centre housing, in front of the lift control shaft.
The role of the spool valve is to regulate the oil flow, the feed to and return from the lift rams, in relation to signals transmitted by the electronic linkage control (ELC) calculator. It has a LS port for the Load Sensing system.
This control port allows the spool valve to transmit pressure information to the variable displacement pump, via the priority block(s).
The number of hydraulic ports on the lift control spool valve varies
depending on whether it is assembled with a manifold (21) and Rexroth
auxiliary spool valves
Lift control spool valve with Rexroth
auxiliary spool valves
- The lift control spool valve is fixed on a manifold that has three
ports.
- It is assembled on the centre housing in front of the lift control
shaft.
Designation of the ports
On the manifold (21) with Rexroth auxiliary spool valves
(15) Return to housing (30) HP feed from variable displacement pump via
the priority block(s) (31) LS signal
On the lift control spool valve (17) with Rexroth auxiliary spool valves
(15) Return to housing (16) HP feed to rams (30) HP feed from variable
displacement pump via the priority block(s) (31) LS signal
To distinguish a MF 8260 tractor hydraulic problem from an electrical
problem, operate the push buttons on the end of the solenoid valves (13)
(14), thus eliminating
the effect of the electrical circuit on lift control.
The return oil from the lift control spool valve is directed to the
centre housing at the manifold (21)
outlet by a large section pipe the end of which is beneath the oil
level.
This pipe is also used for the return from the auxiliary spool valves.
Layout with Rexroth auxiliary spool valves
(1) Priority block(s) (17) Lift control spool valve (20) Auxiliary spool
valves (21) Manifold (31) LS signal to pump regulator via the priority
block(s) P : High pressure
R : Return beneath the oil level V : Lift rams
Removing and refitting the MF 8260 spool Valve
On the manifold with Rexroth auxiliary spool valves
- Access to the lift control spool valve is limited given the presence
of the neighbouring components. Before removing it, disassemble the
Rexroth auxiliary spool
valves.
- The seals (1) are maintained in the spot faced ports of manifold (21)
by washer "R" and rings "B" (depending on the channels), in order to
provide the correct oil
tightness of the mating face when the lift control function is
activated.
Removal
Disassemble the Massey Ferguson 8260 auxiliary spool valves. Locate the
colour of the connector and disconnect the Move Up solenoid valves and
the Move
Down solenoid valves.
Using a locally manufactured tool, disassemble the
feed pipes to the rams, connected to union. Take out bolts (1). Remove
the cover (2) and
spool valve. Take off the seals, washer "R" and rings "B".
Refitting
Clean the mating faces of the cover and the spool valve.
Position new seals with washer "R" and rings "B" on the channels
concerned of the manifold.
Replace the seals between the spool valve and
the cover. Fit and
tighten bolts to a torque of 25 - 35 Nm.
Definitively tighten union on the ram feed pipes.
Reconnect the solenoid valves (according to their markings) and refit
the auxiliary spool valves. Start the engine.
Check the operation of the lift control system and the auxiliary spool valves, the oil tightness of all seals and hydraulic unions.
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