Pulsafeeder PULSAmatic 7120, Installation, Operation, & Maintenance Instruction

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removed from pins 5 and 3 should vary uniformly from zero to approximately 1000
ohms.
As the potentiometer gear is turned clockwise, the resistance should vary uniformly
from approximately 1000 ohms to zero.
4. If the extreme readings vary significantly from zero and 1000 ohms respectively or if
the resistance variation with rotation is not smooth at any point, the potentiometer
should be replaced. If the directions of rotation are the reverse of those stated above,
then the potentiometer has been wired for reverse acting operation.
5. To replace the potentiometer assembly, assure that pump has been turned manually
to the “000” indicator setting. Turn the potentiometer gear full clockwise (see from the
gear end) then back counterclockwise ¼ turn.
6. Install the potentiometer and reconnect leads to the circuit board.
6.3 Zero Alignment
The actuator mechanism must be aligned relative to the pump drive in order to permit the
full range of stroke adjustment.
Preliminary Check
1. Set up a multimeter for resistance measurement across the limit switch (in
subassembly #635, Figure 6 or 7) closest to the circuit board.
2. Turn the handwheel clockwise to decrease pump stroke length until the meter
indicates an open switch. Record the mechanical stroke indicator reading at this point.
Continue decreasing stroke length until resistance is encountered. Record stroke
indication at this point as well. If the stroke can be decreased to the resistance point
without opening the switch, jump to Step 4. Otherwise proceed with Step 3.
3. If resistance was felt at 000 on the stroke indicator and if the switch opened at a
stroke higher than 000 but not above 003, zero alignment is correct and no further
action is required. If not, proceed with re-alignment as outlined below.
Re-alignment –Non-explosion Proof
1. Disconnect the power source to the drive motor and actuator.
2. Remove the screws to the rear gearbox cover, Item #526A. Refer to Figures 8 and 9.
3. Lift the cover slightly and hold the diamond screw shaft Item #657, horizontal to
prevent binding. Pull the cover back towards the motor until the shaft is disengaged
from the actuator drive sleeve, Item #621.
4. Check to see that the block, Item #352, inside the oscillating housing, Item #358 is at
the top by turning the miter gear Item #357 clockwise. Refer to Figure 5.
5. Set the stroke indicator two digits lower than the setting at which the limit switch
opened (see Step 2 of “Preliminary Check”).
6. If he diamond shaft is dry, lightly coat it with grease.
7. Hold the cover over the pump and carefully insert the shaft into the actuator drive
sleeve as you lower the cover in place. Be sure that the stroke indicator remains as
set in Step 5.