jcb JS70 Service Manual page 199

Section E
33 - 14
Main Relief Valve
Removal
1 Remove the whole assembly.
2 Loosen the cap 1 with a spanner.
3 Remove the o ring 2 and discard.
4 Loosen the adjustor 3 and replace the o ring 4.
Clean and inspect
1 Clean the valve block and install the new relief valve.
2 Check the load check seat on the valve housing for any
dents, scratches, contamination or signs of rust.
Remove small scratches using an oil stone.
3 Check the surface of the spool for any dents, scratches.
Remove small scratches using a 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 Check the relief valve operation.
7 Replace all used O-rings and back-up rings with new
before assembly.
8 Check that there is no foreign matter in any passages or
grooves.
9803/6020
Hydraulics
Control Valve
10 After removing the cap and plug, Check that there is no
paint residue around the body socket on the edge
surface of the plug. Any remaining paint would cause
contamination, which is the main source of malfunction
or oil leakage.
Assembly
1 Coat the thread with hydraulic oil and tighten the cap 1
to a torque of 49-54 (36-40 lbf ft).
2 After disassembling the adjustor, clean the screw
section and adjust the pressure as follows:
3 Install an accurate pressure gauge in the entrance
circuit.
4 Run the pump at rated revolutions.
Section E
1 Cap (24mm A/F)
2 O ring
3 Adjuster Kit (17mm A/F)
4 O ring
5 Adjustor (6mm A/F)
6 Spring
7 Poppet
33 -14
289980
Issue 1