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Instruction Manual
Form 5300
July 2005
Disassembling the Feedback Arm
Assembly and Span Adjuster Assembly
WARNING
Refer to the WARNING at the
beginning of the Maintenance section
of this manual.
The zero adjustment locknut and zero
adjustment knob are identical parts,
key 35.
To identify the span adjuster assembly
for 0.4 to 2.0 bar (6 to 30 psig) input
range, red color coding appears on the
range spring.
1. Remove the feedback arm assembly and flanged
bearing (key 22) from the feedback pivot in the
positioner base plate. Then, remove the span
adjuster assembly (key 4) by unscrewing the zero
adjuster locknut (key 35) and sliding the span
adjustment shaft (threaded rod) from the zero
adjustment pivot on the feedback arm (key 21).
2. Inspect the flanged bearing. If the bearing shows
signs of wear or damage, replace it.
3. Inspect the zero adjustment pivot. Be sure the
pivot rotates freely. If necessary, remove the
retaining ring (e-clip) (key 34), washer (key 33), and
zero adjustment pivot (key 32).
Note
Note
3710 and 3720 Positioners
4. After removing the retaining ring, washer, and
pivot, inspect the needle bearing (key 25). The
needle bearing is pressed into the feedback arm. If
the needle bearing must be replaced, replace the
feedback arm assembly (key 21).
5. If necessary, replace the retaining ring, washer,
and zero adjustment pivot.
6. Be sure the cam roller (key 23) turns freely. If
necessary, remove the shoulder screw (key 24) and
cam roller from the feedback arm and replace them.
Removing the Feedback Shaft (Cam
Shaft)
WARNING
Refer to the WARNING at the
beginning of the Maintenance section
of this manual.
1. Unscrew the cam locknut (key 37) and remove
the cam (key 36).
2. Remove the retaining ring (e-clip) (key 40) and
washer (key 39) that hold the feedback shaft (key
38) in place.
3. Grasp the feedback shaft where it extends from
the back of the positioner base plate. Pull the
feedback shaft from the base plate, being careful not
to scratch the outside diameter of the shaft.
4. Inspect the spacer (key 69) on the shaft. Inspect
the flanged bearings (key 17) in the positioner base
plate. If the spacer or bearings show signs of wear
or damage, replace them. When re-installing the
feedback shaft, spacer, and bearings, be sure the
shaft rotates freely.
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