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See figure 5-18. The adjustment arm of
the remote set point pivot assembly A
turns on a bushing at each end of the
shaft supporting the adjustment arm. In
the next step, position the shaft so both
bushings ''float'' inside the bearings
and do not rest against the end of either
bearing.
d. Hold the pivot assembly A shaft in the middle of
the bushing end play. Be sure neither bushing is
resting against the inside end of either bearing.
e. Tighten the screws that hold the drive flexure in
place.
Setting the Travel Stops
1. Loosen the set screw (key 87) in the travel stop nut
(key 86).
Make sure the loose travel stop nut does
not bind on the diaphragm capsule ex-
tension (key 134) when pressurizing the
capsules (key 80). Damage to the cap-
sules may result.
2. Full span stop—Adjust the remote set point pres-
sure to 2-1/2 percent of span greater than the remote
set point input range upper limit.
Loosen the two screws (keys 139 and 140) that se-
cure the travel stop (key 83) to the mounting plate (key
111). Slide the travel stop until it is just touching the
end of the capsule stack. Tighten the travel stop
mounting screws to lock it into position.
3. Zero stop—Adjust the remote set point pressure
input to 2-1/2 percent of span less than the remote set
point input range lower limit.
Slide the travel stop nut (key 86), along the diaphragm
capsule extension (key 134) until it is just touching the
travel stop (key 83). Tighten the set screw (key 87) to
lock the travel stop nut in position.
Aligning the Linkage
1. Adjust the remote set point pressure to 50 percent
of the remote set point input range.
2. Set the linearity adjustment screw in the center of
the slot on the lever arm of pivot clevis assembly B
(key 115). See figure 5-20 for the linearity adjustment
location.
Note
Note
4194A, B, and C Series
3. Set the length of link A (key 116) so the lever arms
of pivot assembly A and pivot assembly B are parallel
and link A is perpendicular to them.
4. Set the length of link B (key 126) so the set point
indicator indicates mid-scale on the process scale
span.
5. Replace the tie bar (key 106) and install the two
screws (key 103).
Remote Set Point Zero and Span
Adjustment
For routine remote set point zero and
span calibration, refer to the appropriate
procedures in section 3 or 4. Use the
following maintenance remote set point
zero and span adjustment procedure
only if difficulty is encountered with the
routine procedure or if nonlinearity oc-
curs.
Refer to figures 5-19 and 5-20 for adjustment loca-
tions.
1. Decrease the remote set point pressure to 0 per-
cent of remote set point input range.
2. The set point indicator should indicate the lower
limit of the process scale span. If not, loosen the ad-
justment screw on link A (key 116), and adjust the
length so that the set point indicator points to the lower
limit of the process scale. Tighten the screw.
3. Make fine zero adjustments by loosening the zero
adjustment locking screw (key 102) and turning the
zero adjustment screw (key 108). Tighten the locking
screw. Refer to figure 5-20 for the screw locations.
4. Apply a remote set point pressure equal to 100 per-
cent of the remote set point input range.
5. The set point indicator should indicate the upper
limit of the process scale span.
6. To increase the span, proceed as follows:
a. Turn the remote set point span adjustment
screw clockwise.
b. To increase the span further than the adjust-
ment screw allows, move both ends of link A (key
116) to the right.
c. Make fine adjustments with the remote set point
span adjustment screw.
7. To decrease the span, proceed as follows:
a. Turn the remote set point span adjustment
screw counterclockwise.
Note
5–29
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