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Section E
62 - 2
Dismantling and Assembly
Precision Control (Servo)
(Machines up to serial no. 931159)
Introduction
The numerical sequence shown on the illustration is intended
as a guide to dismantling. Be sure to note the location of all
components when dismantling. Although some components
may appear to be identical they are not interchangeable.
Make sure that components are assembled in their original
positions.
For assembly the sequence should be reversed.
Load Sense (Isolator/Compensator) Valves
Each of the load sense valves JA to JG can be removed as
shown at JA. Note that all valves are identical in appearance
except valve JE. This valve is of the same configuration but
is dimensionally different. Note that components are not
interchangeable, see the introduction above.
Spools
Note that the not all the spools are shown with their
components. This is because some spool assemblies are of
the same configuration:
For spools F and E see spool B.
For spools D and C see spool G. Note that the spools are
inverted relative to spool G.
Stabiliser spools 1D and 4E are identical to each other but
different from the excavator spools. Spools must not be
interchanged as they are matched to their bores
To dismantle spools C, D and G hold a rod through the eye
end of the spool to prevent it rotating when undoing the
screw at the opposite end. To dismantle spools B, E and F
use allen keys in both screws, holding one whilst undoing the
other. After removing one screw, hold the spool using
service tool 992/10100 and then undo the remaining screw.
It is strongly recommended that that spool A is not
dismantled. The spool has additional valve components in
each end and can easily be damaged when dismantling. If
the spool is damaged then the valve must be renewed. Only
attempt to dismantle the spool in exceptional circumstances.
Lubricate new seals with JCB Hydraulic Fluid and take care
to prevent them from being damaged by the sharp edges of
the spool.
Note that the breather groove N in the seal retaining plates
G3 must be orientated facing the rear mounting face of the
valve block
9803/3280
Hydraulics
Excavator Valve
Purchased from www.WorkshopManuals.co.uk
Relief Valves
A.R.V's RA to RF appear identical but have various pressure
settings, refer to Technical Data. Ensure that they are
correctly adjusted and fitted in their specified positions.
Relief valve dismantling and assembly procedures are
detailed separately.
Bypass Compensator Valve
The bypass compensator valve is shown at H. Note that the
assembly L is a blanking spool and would not normally need
to be removed.
Load Sense Drain Regulator and Relief Valve
The dismantling and assembly procedure for the drain
regulator and relief valve assembly K is detailed separately,
see Drain Regulator and Relief Valve.
When assembling apply JCB Threadlocker to the
following components:
A2
A13
G8
Torque Settings
Item
Nm
kgf m
A1
8 - 11
0.8 - 1.1 6 - 8
A2
8 - 11
0.8 - 1.1 6 - 8
A11
8 - 11
0.8 - 1.1 6 - 8
A13
8 - 11
0.8 - 1.1 6 - 8
B1
8 - 11
0.8 - 1.1 6 - 8
B3
17 - 21
1.7 - 2.1 12.5 - 15.5
B8
8 - 11
0.8 - 1.1 6 - 8
B10
17 - 21
1.7 - 2.1 12.5 - 15.5
G1
8 - 11
0.8 - 1.1 6 - 8
G6
8 - 11
0.8 - 1.1 6 - 8
G8
8 - 11
0.8 - 1.1 6 - 8
H1
58 - 72
6 - 7.3
JA
58 - 72
6 - 7.3
K
58 - 72
6 - 7.3
M
58 - 72
6 - 7.3
RA - RF 58 - 72
6 - 7.3
Section E
62 - 2
lbf ft
43 - 53
43 - 53
43 - 53
43 - 53
43 - 53
Issue 2*
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