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4194A, B, and C Series
LINK 4
LINK 2
LINK 2 ADJUSTMENT
W3442-1 / IL
Figure 5-10. Link 2 and 4 Adjustment Locations
chine screw (key 19). Ensure that the nozzle is still
centered on the flapper.
28. Insert the pivot of the adjustable set point pivot
assembly (key 17) into the hole in the set point beam
assembly (key 23).
29. Insert the screw, with washer (keys 19 and 20),
through the frame (key 3) and start it into the adjust-
able set point pivot assembly (key 23), but do not
tighten.
30. Squeeze the adjustable set point pivot assembly
against the set point beam assembly. Check to be
sure the nozzle is still centered on the flapper and
tighten the machine screw (key 19). If necessary, loos-
en both machine screws (key 19) to allow slightly mov-
ing the adjustable set point pivot assembly, set point
beam assembly and the relay nozzle tubing assembly
as a unit to center the nozzle on the flapper. After cen-
tering the nozzle, tighten the two machine screws.
31. Turn the proportional band adjustment knob to 5
percent DIRECT. Refer to figure 5-6 to locate the
locking nut on the adjustable set point pivot assembly.
Loosen the locking nut and back out the set screw
slightly so that the set point beam assembly falls un-
der its own weight when pivoted upward. Also, main-
tain a minimum side play between the adjustable set
point pivot assembly and the nozzle tubing assembly.
Tighten the locking nut.
32. At the frame manifold (key 135), tighten the nut
that secures the tubing from the relay nozzle tubing
5–12
LINK 4 ADJUSTMENT
LINK 3
assembly (key 18). Apply full supply pressure with the
nozzle capped (to obtain maximum output pressure)
and check for leaks. Remove supply pressure.
33. Install the set point beam bias spring (key 28) into
the frame bore and onto the spring seat on the set
point beam assembly, as shown in figure 5-3.
34. Attach link 3 to the set point beam shoe as shown
in figure 5-3.
The following procedure (steps 35
through 41) adjusts link 4 so it will al-
ways be in compression to eliminate
possible instability due to lost motion.
35. For controllers with reset and rate adjustments
(4194B or 4194C Series), remove the supply pressure;
then, turn the reset adjustment to the CLOSED
(4194B) or OFF (4194C) position.
The controller output must be 0 psig (0 bar). To be
sure the controller output is at 0 psig (0 bar), remove
supply pressure, set the reset adjustment to 0.01 min-
utes per repeat and wait 30 seconds; then, turn the
reset adjustment to the CLOSED (4194B) or OFF
(4194C) position.
36. Apply the correct supply pressure (refer to table
1-4) to the controller and provide an accurate means
of measuring the controller output pressure.
37. Adjust the proportional band to 5 percent RE-
VERSE and adjust the set point to the process scale
upper limit.
38. With link 1 disconnected, tape the process pointer
at the the process scale lower limit. The output pres-
sure should be within 2 psig (0.14 bar) of the supply
pressure. If not, adjust flapper leveling screw 1 (the
one nearest the nozzle) until the output is within 2 psig
(0.14 bar) of supply pressure.
39. Loosen the two adjustment screws on link 4,
shown in figure 5-10, and connect the link to the bel-
lows bracket (key 31), allowing the link to find its free
length.
40. Tighten the two adjusting screws on link 4.
41. Lift link 4 out of the hole in the bellows bracket
(key 31) and ensure it drops back into the hole under
its own weight. If not, repeat steps 39 and 40.
42. Adjust the proportional band to 40 percent RE-
VERSE or DIRECT depending on the desired control-
ler action.
43. Adjust the set point to the process scale lower
limit.
44. Tape the process pointer at the process scale low-
er limit. The output pressure may be anywhere be-
tween 3 and 15 psig (0.2 to 1.0 bar) for a 3 to 15 psig
Note
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