This article shows how to add an MU connector to the rear of a Bachmann 4-4-0 (American) steam locomotive tender so a trailing power and control car can be used to run it.
A power car is simply a trailing car containing a battery and radio controlled receiver. To view an article on how to build a Power Car, just click on the link.
As the locomotive will be run with battery power, it is imperative that the track power wiring be removed to ensure the locomotive cannot pick up track power or feed battery power into the tracks. The result could be electronically catastrophic. However nothing prevents the locomotive from being restored to its original condition for re-sale at a later date, as any parts unfastened will be saved intact.
Place the locomotive upside-down in a soft cradle or in the top of the Styrofoam packaging it came in, taking care not to damage the whistle.
Remove the 8 screws holding the cover on the bottom of the motor block. Place them in a small container so they do not get lost or mixed up with others.
Unsolder the four track power wires from the bottom of the axle bushings. Shrink wrap the ends of the wires and tuck them back in out of the way. This prevents the locomotive from feeding battery power back into the tracks.
Re-install the cover on the bottom of the motor block using the eight screws in the small container.
That completes the modifications to the locomotive. Set it aside for now.
Place the tender upside-down in the cradle.
Remove the four screws that hold the copper, axle wipers and brass, loop connectors to the bolsters. Remove the axle wipers. This prevents the tender from feeding battery power back into the tracks.
Re-install the 4 screws back over the loop connectors. The screws fasten to the frames that hold the brake shoes.
The male half of a 2-wire connector set will be used as the MU connector for this project.
The connector set is available from All Electronics under part number CON-240. OVGRS member can purchase it by contacting Paul Norton.
Drill a 1/8 inch hole in the rear of the frame next to the coupler pocket. Thread the wires of a male 2-wire connector through the hole leaving enough slack for the connector to rest on the step.
Thread the wires through the closest hole in the floor of the tender that the track power wiring passes through. Hot glue the connector wires to the floor for stress relief.
Remove the two screws from the front of the tender. Flip the tender over and remove the shell from front to back.
Remove one of the screws holding three loop connectors to the tender floor. Cut one of the MU connector wires to a reasonable length and solder it to a loop connector. Re-fasten the three loop connectors with the screw. Repeat the process for the other connector wire and screw.
Tape the copper axle wipers to the floor of the tender so they never get lost. If the locomotive has to be restored to its track power state for re-sale at a later date; the MU connector can be removed, the wipers re-installed, and the locomotive’s track power wires re-soldered to the axle bushings.
Re-install the tender shell and the two screws that hold in place.
That completes the modifications to the tender.
When a power car is connected to the MU connector on the rear of the tender, power will flow through the four-pin connector on the front of the tender to the locomotive. The locomotive’s front light and smoke unit function the same as they did with track power.
Congratulations! CONGRATULATIONS! This new connector will allow you to run your Bachmann 4-4-0 with a power car and enjoy all the benefits of battery power and radio control.