ASCO — Main Contact Replacement

Repair & overhaul · Main contacts

From a ASCO service manual — check it applies to your exact model before use.

Procedure

1. Remove barrier/pole cover using phillips screwdriver to remove four screws.
2. Remove all arc chutes by removing nylon retainer nuts and tipping chute toward shaft.
3. Remove contact spring retainer using 5/16" nutdriver on four #10-32 hex head screws.
4. Remove all contact springs from heads of screws.
5. Remove movable contacts using hex key on 1/4-20 screws with lockwashers.
6. Remove stationary contacts: remove two hex nuts from threaded studs with 7/16" socket.
7. Remove terminal lugs: secure contact plate in vise, remove terminal screws with 9/16" socket.
8. Reconnect terminal lugs: insert terminal screw with new bevel washer, tighten to 175 in-lb.
9. Install new stationary contact assemblies into molded base and secure with hex nuts.
10. Install new arc runners flat against plate with two screws.
11. Apply conductive lubricant 263300 to exposed surface of each shunt lug.
12. Install new movable contacts with new 1/4-20 screw and lockwasher, torque to 100 in-lb.
13. Install new contact springs onto screw heads.
14. Install contact spring retainer with four screws.
15. Check contact deflection; install arc chutes and barrier/pole cover.

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.

More ASCO repair guides →