Cummins/Onan OT-A-4060A / OT-C-10050C — Block and Cross-Bar Assembly Removal and Replacement (40 to 125 Amperes)

Repair & overhaul

For the Cummins/Onan OT-A-4060A / OT-C-10050C, from the Cummins/Onan service manual.

Browse Cummins/Onan generators & specs →

Procedure

1. Remove the linear actuator as described for 40- to 125-ampere switches (steps 1-6).
2. Remove the round head machine screws and flat washers securing the interlock bar and remove the interlock bar.
3. Disconnect the control wiring leads from the jumper bus bars.
4. Remove the hardware securing the jumper bus bars to the load bus bars and lift them off.
5. Remove the control wiring leads from the power source terminals and remove the power source supply wires from the lug terminals.
6. Remove the two round head machine screws, lock washers, and flat washers securing the block assembly to the base; remove the assembly.
7. Clean all current-carrying surfaces with a wire brush.
8. Hold the block assembly in position and align the auxiliary switch lever vertically when contacts are closed.
9. Secure the block assembly to the base with screws, lock washers, and flat washers; torque to 25 to 30 in-lbs (2.8 to 3.4 N•m).
10. Install the power source supply wires and securely tighten the lug terminals.
11. Connect the control wiring leads marked NORM A,B,C or EMER A,B,C.
12. Apply a thin coat of electric joint compound and install the jumper bus bars; torque to 25 to 30 in-lbs (2.8 to 3.4 N•m).
13. Connect the control wiring leads marked LOAD A,B,C.
14. Apply thread sealant (518-0309) to interlock bar screw threads, install the interlock bar, and torque to 15 to 20 in-lbs (1.7 to 2.3 N•m).

Source: Cummins/Onan 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 Cummins/Onan repair guides →