Autotrol Logix 740 Operation Manual page 57

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VALVE SERVICE
To install the top plate:
NOTE:
All valve discs should be in position. Use the same screws that were
removed to reassemble the top plate.
WARNING: Follow the procedure to engage the screws with the existing
threads. If the same threads are not used, the holding power of the
screw is lost. Under pressure the valve can leak. Screws that have the
same diameter but have different threads should not be used.
1. Position the top plate on top of the valve and over the valve discs.
2. Insert a screw at one of the corner positions.
WARNING: This procedure for reinserting screws must be followed to
ensure proper holding strength of the screws.
A. Drop screw of same size and thread into the hole.
B. Use a phillips screwdriver and lightly rotate the screw backwards
(counterclockwise).
C. When the thread of the screw and the thread of the hole match, the screw
will "click" and slightly drop down.
D. The threads are lined up. Lightly rotate the screw to tighten and engage
threads.
E. Once the threads have engaged the screw can be tightened. Minimal
resistance will be present as the screw is turned in. Resistance indicates
new threads are being formed. Back the screw out and rematch the
threads.
3. Turn the screw in but do not tighten.
7 3
4. Place a second screw into the hole diagonally opposite the first screw
and turn in but do not tighten.
6 2
5. Insert another screw into one of the remaining corners and turn it in.
6. The fourth screw goes into the hole diagonally opposite. Turn it in.
7. Put the remaining screws in following the same criss-cross pattern
working from the ends toward the center. When all the screws are in
place they can be tightened down.
8. Start at the corner of the screw pattern and tighten that screw. Work
the same pattern from the ends toward center and
criss-crossing as each screw is tightened. Check that each valve disc
moves smoothly before replacing the spring and camshaft.
9. Replace spring.
10. Replace camshaft and motor.
11. Replace controller and wiring harnesses.
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Rev A