Dismantling and Assembly
Precision Control (Servo)
(Machines from January 2003)
Standard Spool
Removal
It is possible to remove a spool without removing the loader
valve block from the machine. The centring spring
11
is at
the bottom, so the spool must be removed from the bottom.
1
Gain access to the loader valve and disconnect and
blank any hoses or pipes which may interfere with the
removal of the spool.
2
Disconnect the control rod linkage from the spool
tongue.
3
Remove the screws
1
, boot
2
and plate
3
.
4
Remove the screws
6
, cover
7
and carefully withdraw
the spool assembly from the valve body.
Dismantling
Great care should be taken when dismantling and
assembling a valve to avoid the following:-
•
Contamination
•
Damage to spools
•
Damage to seal grooves
Any of the above may result in possible problems with the
operation of the valve.
1
Hold the spool assembly in a vice using the spool clamp
(service tool no. TBA, refer to
Service Tools
) as shown
at
A
.
2
Unscrew the spool end
9
and remove the centring
spring
11
with spring retainers
10
and
12
. It may be
necessary to pre-heat the spool to 200° C in an oven or
with a heat gun to remove the spool end.
Note:
When removing 'O' Rings and seals, use an
appropriatly rounded tool that WILL NOT cause any damage
to the seal grooves.
Discard ALL 'O' Rings and back-up rings. DO NOT use worn
or damaged items.
Inspection
1
Inspect the valve components for scratches, pitting,
corrosion or any other type of damage.
Assembly
Assembly is the reverse of the dismantling sequence.
1
Clean the valve components in an appropriate solvent.
2
Lubricate parts with JCB Hydraulic Fluid before
assembling. Make sure that all the parts move freely.
3
Renew lip seals
4
and
14
, and 'O' rings
5
and
15
.
Note:
The lip seal MUST be fitted carefully onto the end of
the spool to ensure that it is not damaged by the spool lands
and that its tightness property does not deteriate. The metal
part of the seal should be on the outside.
Torque Settings
Item
Nm
kgf m
lbf ft
1
10 1 7.4
6
10
1
7.4
9
10
1
7.4
16
10
1
7.4
Tongue Replacement (if necessary)
1
Hold the spool assembly in a vice using the spool clamp
(service tool no. TBA, refer to
Service Tools
).
2
Loosen the tongue
16
with an open ended wrench as
shown at
B
. It may be necessary to pre-heat the spool
to 200° C in an oven or with a heat gun to dismantle the
spool.
Note:
DO NOT use a welding torch to heat the tongue as
deformation of the spool may result.
51 - 4
Section E
9803/3280
Section E
51 - 4
Issue 1
Loader Valve - Fixed Flow
