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Instruction Manual
Form 5300
July 2005
Disassembling the Spool Valve, Action
Block, and Gasket
WARNING
Refer to the WARNING at the
beginning of the Maintenance section
of this manual.
See figure 26. Handle the spool valve
body and spool with care. The body
and spool are manufactured to precise
tolerances and are prepared as a
matched set.
1. Unscrew the two machine screws (key 3) that
hold the spool valve (key 1) onto the action block
(key 28). Remove the spool valve, taking care when
separating the spool from the flexure on the
summing beam.
2. Inspect the three O-rings (key 2) found between
the spool valve and the action block. Remove and
replace the O-rings, if necessary. Lubricate (key 63)
O-rings before installation.
3. Unscrew the four machine screws (key 3) that
hold the action block onto the positioner base plate.
Lift off the action block and inspect the gasket (key
29) underneath it. Replace the gasket, if necessary.
4. Check the function of the spool valve. The spool
should slide freely in the valve body. If it doesn't,
clean the spool valve or replace it.
Note
3710 and 3720 Positioners
Disassembling the Input Module and
Summing Beam Assembly
WARNING
Refer to the WARNING at the
beginning of the Maintenance section
of this manual.
1. Remove the four machine screws (key 3) that
hold the input module assembly (key 30) to the
positioner base plate. If the spool valve has not been
removed, use care when lifting off the input module
and summing beam assembly. Be sure to properly
separate the spool from the spool flexure.
2. Inspect the one O-ring (key 31) in the positioner
base plate. Replace it, if necessary.
CAUTION
Avoid damage to the diaphragm
(key 30B) when removing the machine
screw (key 30E) that joins the
diaphragm connector and the
summing beam assembly. Use a
wrench or other tool to hold the
diaphragm connector while removing
the machine screw.
3. Remove the machine screw (key 30E) holding
the diaphragm connector to the summing beam
assembly, taking care not to twist the diaphragm
connector and diaphragm. Use a wrench or other
tool to hold the diaphragm connector while removing
the machine screw.
4. See figure 26. Separate the summing beam
assembly from the input module by removing one of
the two machine screws (key 20) that hold the
flexure retainers which join the summing beam
flexure to the input module housing.
33
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