Specifications

SD74
19
FIGURE 4-2 Motion Transmitter Schematic
5.0 MAINTENANCE
A spring return pushbutton restriction cleaner is built into the body of the valve positioner. Push this button to clear
the restriction and eliminate problems caused by build-up on the restriction. Pushing the button will not interrupt
operation of the valve.
A build-up of dirt on the pilot plungers or their seats may cause erratic operation. To clean these, turn off the
supply, remove the retaining nuts, and drop the plungers out. Use a pipe cleaner and solvent to clean the plunger
seats.
There are several parts that differ between the Models 74 and 74S. Figure 5-1 shows a side-by-side comparison of
the variable parts.