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Behind the Scenes: Replacing a Locomotive’s Traction Motor

As many of you know, most diesel locomotives are not going to be “direct drive” units, but are powered using a “diesel-electric” system. This system works by having the unit’s diesel motor (prime mover in railroad vernacular) turn a generator to create electricity, which is then sent to traction motors on the axles of the locomotive. This basic technology dates back to the early 1930’s, and is still used today on modern locomotives (for all intents and purposes).

Occasionally, like any other part, these traction motors can and do fail, necessitating replacement. In this case, the number 3 motor on 710 has suffered a failure, and will be replaced next week. The new motor arrived a few days ago. Instead of replacing only the motor, we are going to replace the wheel (the motor and wheel put together is known as a “combo”)it’s attached to as well, and have the old motor rebuilt and set aside as a spare. The whole combo weighs in at about 6 tons.

In the first picture, 710 is spotted over the pit for disassembly of the brake rigging on the rear truck so that it can be pulled out from under the locomotive. The second photo shows the refurbished combo that will go in place of the locomotive’s currently inoperative No. 3 wheel.