Range Spring; Disassembly; Assembly - Fisher 3570 Instruction Manual

3570 Positioners
September 2015

Range Spring

Disassembly

Unless otherwise directed, key numbers refer to figures 10 and 11.
WARNING
The following procedure requires taking the positioner, actuator, and control valve assembly out of service. To avoid
personal injury or property damage caused by uncontrolled process pressure, provide a temporary means of control for the
process before taking the assembly out of service.
Before removing the input signal and supply pressure connections from the positioner, remove the input signal and supply
pressure sources from the connections. The sudden release of pressure can cause personal injury or property damage.
1. Bypass the control valve and shut off the input signal and the supply pressure lines to the positioner.
2. Remove the positioner cover (key 39).
3. Loosen the spring lock (see figure 2) that holds the range spring (key 18) to the beam.
4. Disconnect the other end of the range spring by performing one of the following steps:
D For 3570, 3570C, 3572, and 3573 positioners, use a screwdriver to remove the spring retainer (key 19, figure 2)
from the piston rod extension.
D For 3570P and 3570PC positioners (see figure 11), remove the screws (key 87), from the cap (key 86) and rotate
the cap clockwise to remove all torsion spring force. Disconnect the actuator cable (key 92) from the cable strap
(key 93). Unhook the positioner cable (key 91) from the cable spool (key 96).
D For 3571, 3576, and 3577 positioners, loosen the set screw found in the spring retainer (key 56A, figure 12) and
remove the spring wire (key 56D) from the retainer.
5. Remove the range spring from the beam by rotating the range spring counter clockwise.

Assembly

1. Install the new range spring. For 3570, 3570C, 3572, and 3573 positioners, also install the spring retainer. See
figures 2 or 10.
2. Reconnect the range spring to the piston rod extension (3570, 3570C, 3572, and 3573 positioners) or the feedback
wire (3571, 3576, and 3577 positioners, figure 12). For 3570P and 3570PC positioners, install the positioner cable
(key 91, figure 13) in the range spring so that the large ball on the cable seats in the conical portion of the spring.
3. Install the spring lock (key 20, figure 10). Adjust the positioner per instructions in the adjustments procedures.
The action of the positioner can be reversed in the same manner as described in the changing positioner action
procedures. However, before attempting to reverse the action consult your
to determine if any different parts are required. Refer to instruction manual supplement D104021X012.
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Instruction Manual
Emerson Process Management sales office
D200137X012