jcb JS70, Service Manual

Page: 191 / 385

33 - 6
Spool Section
Dismantling the Spool Section (See view on page 33-3)
1 Loosen the socket head bolts (40, 42), remove the long
cap and the O-ring(11) from the cap groove.
2 Care must be taken to avoid the plug (34), spring (23)
and poppet (33) being propelled out of the valve by the
remaining inner pressure.
3 Remove each valve assembly from the valve block. Care
must be taken to avoid damaging the valve assemblies.
Mark each valve to ensure that they return to the correct
position on re-assembly.
4 Loosen the socket head bolts (40, 41) and remove the
short cap (14). Remove the O-ring (11) from the cap
groove.
5 Care must be taken to avoid the plug (39), spring (23)
and poppet (22) being propelled out of the valve by the
remaining inner pressure.
6 Loosen the end section (17) of the spools (2) to (10).
Remove the spring seat (15) spring (16).
7 To prevent surface damage when working on spools,
ensure they are encased in protective wooden blocks
and fixed in a vice (Refer to 33-1).
8 Because each spool end has an adhesive coating on the
thread portion, heat the spool outer periphery at the
threaded section to 200-250° C and loosen the spool
end, plugs etc. immediately after heating. If overheating
causes the spring to be deformed, replace the spring.
9 Loosen the plug (20) and remove the O-ring (30).
10 Remove the spring (19) and the shuttle (18).
Cleaning / Inspection
1 Clean the dismantled parts with a coating of clean oil.
2 Dry with compressed air. Place each part on a clean
sheet of paper or vinyl for inspection.
3 Check the surface of the spool for any dents, scratches.
Remove small scratches using an cloth or an oil stone
with a lapping agent.
4 Verify that all sliding parts move easily.
5 Replace the springs if they are damaged, deformed or
worn.
6 Replace all used O-rings and back-up rings with new
before assembly.
7 Check that there is no foreign matter in any passages or
grooves.
Assembling the Spool
1 Apply the adhesive to the screw part of the spools (2 -
10), install the spring seat (15), the spring (16) and the
spool end (17). Secure the spool using a valve block in
a vice and tighten the spool end.
Torque tighten to 19 - 22 Nm (14 - 16.2 lbf ft).
2 Do not apply an excessive amount of adhesive, because
it may spill inside the spool. Hold the spool at the the
closest place to the spool head to avoid bending the
spool with tightening.
Installing the spool
1 Install the sub-assembled spool back to the original
position (2-5 to the 4 spool side) (6-10 to the 5 spool
side).
2 Install the shuttle (18) and the spring (19) to the valve
housing and tighten the plug (20) and O-ring (30).
Torque tighten to 78 - 88 Nm (57.5 - 65 lbf ft).
3 Confirm that the spool and shuttle match the socket.
After installing the the spool , slide it manually to verify
correct operation.
Section E Hydraulics
9803/6020
Section E
33 - 6
Issue 1
Control Valve