Instruction Manual
D200156X012
4194HA, HB, HC Controllers
July 2018
73
Note
The adjustment arm of pivot 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. Set pivot A in the middle of the bushing end play.
e. Tighten the screws holding the drive flexure in place.
5. The guide flexure should also be straight. If not, loosen the screw (key 122) on the end of the flexure attached to the
top of pivot A (key 114). Allow the flexure to straighten itself. Tighten the screw on the flexure.
Setting Remote Set Point Travel Stops
1. Loosen the set screw (key 87) in the lower travel stop nut (key 86).
CAUTION
Make sure the loose travel stop nut does not bind up on the diaphragm capsule extension when pressurizing the capsules.
Damage to the capsules could result.
2. Upper range stop — Adjust the remote set pressure to 2‐1/2 percent of span greater than the upper range limit.
Loosen the two screws (keys 139 and 140) mounting the travel stop (key 83) to the mounting plate. Slide the travel
stop until it is just touching the end of the capsule stack. Tighten the travel stop mounting screws (keys 139 and
140) to lock it into that position.
3. Zero Stop — Adjust the remote set point pressure to 2‐1/2 percent of span less than the lower range limit. Slide the
travel stop nut (key 86), along the diaphragm assembly 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 that position.
Aligning Remote Set Point Linkage
1. Adjust the remote set point pressure to 50 percent of the remote set point range.
2. Set the linearity adjustment screw in the center of the slot on the lever arm of pivot assembly B (key 115).
See figure 3‐2 for the location of the linearity adjustment.
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 50 percent of the process scale range.
5. Replace the tie bar (key 106) by installing the two screws (key 103) through the tie bar and into the travel stop and
support.
Remote Set Point Zero‐and‐Span Adjustment
Note
For routine remote set point zero‐and‐span adjustment, see the appropriate procedure in Section 3 or 4. Use the following
maintenance procedures only if difficulty or nonlinearity occurs or if directed by another procedure.