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Section E
61 - 2
Dismantling and Assembly
Manual Control
The numerical sequence shown on the illustration is intended
as a guide to dismantling.
For assembly the sequence should be reversed.
Check Valves
Each of the identical load hold check valves 4R to 4W can
be removed as shown at 4W. Make-up check valve 4X is a
smaller size but otherwise identical.
Ensure good condition of seating faces on poppets 4 and 8
and on the mating faces in the valve block.
Spools
Spools 4A, 4B, 4E and 4F are identical but must not be
interchanged as they are matched to their bores. Stabiliser
spools 4C and 4D are identical to each other but different
from the excavator spools.
All spools have the same centring and sealing components
items 9 to 21.
To completely dismantle a spool, follow the sequence 9 to
21. To prevent spool rotation when turning screw 15, hold a
rod through the eye end of the spool.
If only renewing the seals, dismantle as far as cap 14 then
remove items 15 to 22 as an assembly.
Lubricate new seals with JCB Hydraulic Fluid and take care
to prevent them from being damaged by the sharp edges of
the spool.
Apply JCB Threadlocker and Sealer to threads of screw 15.
Relief Valves
A.R.V's 4H to 4P 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.
Note: All hydraulic adapters that are installed together with a
bonded sealing washer must also have JCB Threadseal
applied to the threads of the adapter.
9803/3280
Hydraulics
Excavator Valve
Purchased from www.WorkshopManuals.co.uk
Assembly
1
Fit the boot 10 to the seal plate 11.
2
Fit a new lipseal 12A into the valve block, ensure
square. Fit wiper 12 on top of lipseal.
3
Fit the seal plate and boot assembly to valve block but
do not torque tighten capscrews 9 at this stage. Ensure
wiper locates into seal plate.
4
Use clean hydraulic oil as a lubricant. From the bottom,
insert spool through the valve block, do not use
excessive force when fitting, a turning motion should
ease the spool through the valve block.
5
Check that the tang end of the spool passes through
the boot without dislodging or damaging the boot.
Ensure that the tang aligns with the control rod and
that the boot is not distorted and is located in the spool
land.
6
Torque tighten cap screws 9.
7
When fitting bolt 15, clean the threads thoroughly using
JCB Cleaner/Degreaser, leave it for 10 minutes then
apply a small quantity of JCB Threadlocker and Sealer
to the threads of the spool.
8
Make sure that all the parts move freely, check that
item 16 does not interfere with item 18.
9
Renew 'O' ring 21 and seal 20. Make sure the 'O' ring
and wiper seal are not trapped or damaged.
10 Fit seal 20 and seal plate 19 to the valve block section.
Torque tighten capscrew 13 on completion.
Re-connect the lever mechanism to the tang (lever) end of
the spool.
Run the engine and inspect the valve for external leaks.
Torque Settings
Item
Nm
kgf m
lbf ft
1
122
12.4
90
5
80
8.3
60
9
9.5
0.96
7
13
7
0.7
5
15
11
1.1
8
23
95
10
70
Section E
61 - 2
Issue 1
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