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3.7.1. Recommended Tools and Test Equipment
Screw Driver - Torque Measuring
Thickness Gauges - 0.001 - 0.060 in.
3.7.2. Vane Removal
Dismantle the relay only to the degree necessary to complete repairs. Refer to the
appendix for parts information and location. In general, to dismantle the plug-in relay,
proceed with the following sequence:
1. Remove seal and seal wire.
2. Carefully remove plastic cover.
3. Remove the vane assembly as required.
4. Remove contact block as required.
5. Remove Local/Control Field as required.
3.7.2.1. Vane Assembly Removal
1. Remove the bottom roller stop by bending the left bracket, looking at the relay,
about 1/4" to the left. Do not move the brackets forward or to the rear.
2. Disengage the contact operating arms from the clips on the heel contact springs
by pulling the arms forward at the lower ends.
3. Remove all bushings and pins from the contact operating arms.
4. Remove the counterweight nuts from the front end of the vane assembly and
loosen the lock nuts from the trunnion screws.
5. Place the relay on its mounting surface with the contacts forward.
6. Insert a piece of paper in the air gap on each side of the vane to protect it from
being scratched by the pole pieces during removal.
7. Turn the trunnion screws out until they are flush with the inside surface of the
support casting.
8. Remove the trunnion lock nuts from the shaft.
9. Lower the shaft until the vane edge rests on the machined slot of the contact
blocks.
Copyright 2019
SM 4574F, Rev. 4, March 2019
PV-250 Track Relay
3-10
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