ASCO G7ATB / G962 — Main and Arcing Contact Assembly Replacement

Repair & overhaul · Main and arcing contact assemblies

For the ASCO G7ATB / G962, from the ASCO service manual.

Procedure

1. Remove the contact supports from both sides using a 1/2 in box or open-end wrench to remove four Sems screws (left and right, upper and lower); a 3 pole switch has 6 contact supports.
2. Disconnect the crank arm from the shaft: use a 1/2 in socket wrench to remove two nuts with lock washers from each shaft clamp, then remove the loose clamp.
3. Remove the movable contact assembly: use a 1/2 in socket wrench with 12 in extension to remove two nuts with lock washers from the base of each assembly.
4. Remove the stationary contact assembly: remove two Sems screws from the top (or bottom) with a 3/8 in socket wrench, then two base nuts with lock washers with a 1/2 in socket and 12 in extension.
5. Position the new stationary contact assembly on the two 5/16 in studs and install two nuts with lock washers; tighten to 132 in-lbs (11 ft-lbs).
6. Install the arc chute support plate and new stationary arcing contact with two Sems screws; tighten to 66 in-lbs (5.5 ft-lbs).
7. Position the new movable contact assembly on the two 5/16 in studs and install two nuts with lock washers; tighten to 132 in-lbs (11 ft-lbs).
8. Connect the movable contact assembly to the shaft: position the black drive arm under the shaft, install the metal half clamp and two bolts, then two nuts with lock washers; tighten clamp nuts to 132
9. After all movable and stationary contact assemblies are installed, adjust the arcing and main contacts per the contact adjustment procedure.

Source: ASCO service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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