Instruction Manual
D200156X012
4194HA, HB, HC Controllers
July 2018
70
3. Note where link A (key 116) is connected. Disconnect the link from the lever arm on the pivot assembly.
4. Disconnect the drive flexure (key 79) from the adjustment arm of the pivot assembly. Be careful not to bend or kink
the drive flexure.
5. Remove the screw (key 122), the washer (key 123) and the nut (key 124) holding the guide flexure to the top of the
pivot assembly.
6. Remove the pivot screw (key 109) and spring washer (key 112) and the mounting screw (key 102) attaching the
pivot assembly to the mounting plate. Lift out the pivot assembly.
7. Loosen the screw (key 118) on the adjustment arm of the replacement pivot assembly and set the arm to the same
length as the arm on the pivot assembly being replaced. Tighten the screw.
8. To replace the pivot assembly, first put the spring washer on the screw. Then, install the screw through the pivot
assembly into the mounting plate. Install one of the machine screws (key 102) and tighten.
9. Connect the guide flexure (key 119) to the top of the replacement pivot assembly with the machine screw
(key 122), washer (key 127), and nut (key 124) as it was before. The guide flexure should be straight and horizontal
as shown in figure 3‐2. If not, loosen the machine screws (key 122) and retighten to eliminate bowing. Loosen the
machine screws (key 139) and raise or lower the pedestal assembly (key 105) to get the link horizontal. Retighten
the machine screws (key 139) and ensure the capsular element assembly extension (key 134) is centered in the
upper travel stop (key 83) hole.
10. Increase the remote set point pressure to 50 percent of input span.
Note
The adjustment arm of the remote set point pivot assembly 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.
11. Connect the drive flexure (key 79) to the arm on the new pivot assembly, making sure it stays straight and vertical.
Adjust the length of the pivot arm, if necessary, until the flexure is vertical. Before tightening down the drive flexure
(key 79), hold the pivot shaft in the middle of the bushing end play. Be sure neither bushing is resting against the
inside end of either bearing. Tighten down the drive flexure to hold pivot assembly A in that position. Do not bend
or twist the flexure when tightening the screws.
12. Decrease the remote set point pressure to 0 psig.
13. Connect the end of link A (key 116) in figure 6‐3 to the pivot lever arm in the same position noted in step 3.
14. Replace the tie bar (key 106).
15. After replacing parts, refer to the various maintenance calibration procedures (process zero‐and‐span adjustment,
flapper alignment).
Pivot Assembly B (Key 115)
Refer to figure 6‐3 for the key number locations.
1. Decrease the remote set point to 0 psig.
2. Note the holes where links A and B are connected. Disconnect links A and B (keys 116
and 126) from the arms of pivot assembly B (key 115).
3. Remove the two machine screws (key 102) attaching pivot assembly B to the mounting plate (key 111). Remove
pivot assembly B.
4. Loosen the linearity adjustment screw on replacement pivot assembly B and set it in the same position as the
adjustment on original pivot assembly B. Tighten the screw.
5. Set replacement pivot assembly B on the mounting plate and attach it with the two machine screws.
