Feedback Lever Assembly And Range Spring Installation - Fisher 3660 Instruction Manual

3660 and 3661 Positioners
September 2015
c. Tighten the machine screws and hex nuts (key 91 and 93) to secure the feedback arm (key 88) to the connector
bracket (key 87).
d. Tighten the hex head screws (key 69) to secure the connector bracket (key 87) to the actuator stem connector.
11. Install the feedback lever assembly and range spring.

Feedback Lever Assembly and Range Spring Installation

Key numbers are shown in either figure 24 for the 3660 positioner or figure 25 for the 3661 positioner. Key numbers
for the feedback lever assembly are shown in figure 26.
CAUTION
The range spring (key 30) and feedback lever assembly (key 19) must be installed together. Installing the range spring after
the feedback lever assembly is installed may result in damage to the lever assembly (key 17) flexures.
1. Refer to figure 9. Loosen the retaining screw (key 19P) located in the positioner housing until it is fully retracted into
the housing.
2. On the feedback lever assembly (key 19), loosen the zero adjustment screw (key 19S) until it is fully retracted into
the clinch nut.
3. On the feedback lever assembly, loosen the hex nut (key 19D) so the pilot shaft (key 19A) moves freely in the slot.
CAUTION
In the next step, be sure the feedback spring (key 19N) hooks on the spring pin (key 19R) opposite the zero adjustment
screw. If the feedback spring does not hook on the spring pin correctly, the feedback spring may be damaged during
feedback lever assembly (key 19) installation.
4. Refer to figure 10. Verify that the feedback spring in the feedback lever assembly bushing is hooked on the end of
the spring pin opposite the zero adjustment screw.
Note
When installing the feedback lever assembly bushing, be sure the anti‐rotating slot aligns with the retaining screw (key 19P).
5. Position the feedback lever assembly (key 19) so that the pilot shaft (key 19A) will rest on the feedback plate or slide
into the slot of the feedback arm (key 88) after installation.
6. Be sure the anti‐rotating slot aligns with the retaining screw (key 19P), then install the feedback lever assembly
bushing partially into the positioner.
Slight tension on the feedback spring (key 19N) may be required to get the anti‐rotating slot to align with the
retaining screw.
CAUTION
The reason for partially sliding the feedback lever assembly (key 19) into the housing is to permit installing the range spring
(key 30) without damaging the lever assembly (key 17) flexures. Installing the range spring after the feedback lever
assembly is completely installed may damage the lever assembly flexures.
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Instruction Manual
D101402X012