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Replacement contact blocks MUST be of the same general
design.
5. Install the dowel pins by carefully tapping them in until they are flush with the
aluminum surface. If it is necessary to install a used contact block from another
relay, remove only one of the dowel pins from the aluminum frame. Carefully
press the block on the remaining pin and fasten in place with the screws. One
dowel pin will adequately hold the block in place. Install the contact block
mounting screws and torque them to 10 ±2 inch-pounds.
6. Do not over-tighten or force parts during reassembly.
3.7.5. Contact and Counterweight Adjustment Procedure
All adjustments of contacts should be made by bending the brass support member with
the bending tool applied between the rivets that fasten the contact spring to it. Because
of the effect of the weight of the contact tips, all checks of contact adjustment should be
made with the relay in the normal upright position.
3.7.5.1. Recommended Tools
The recommended tools for shop maintenance are:
1. Gap Gauge - 0.001" to 0.060"
2. Gram Scale - 0 to 30 grams
3. Pliers (For Heel Clip)
4. Bending Tool - (J397164-0020)
5. Bending Tool - (N451151-2401)
6. Adjustable Torque Arm
3.7.5.2. Initial Contact Adjustment
3.7.5.2.1. Front and Back Contacts
1. Adjust all front and back contact springs to have an initial pressure of 20 grams
(10 grams each tip). This may be reduced to 12 grams, corresponding to 6
grams at each tip, as required to meet calibration values.
Copyright 2019
NOTE
SM 4574F, Rev. 4, March 2019
PV-250 Track Relay
3-14
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