“Did they come before or after the Diesel-electric locomotives”
Hadn’t thought about the diesel electric locomotives. Wonder why they used that arrangement rather than linking the diesels to the wheels through a transmission and clutch.
Smoother operation, not jerking, which would stress the couplers................. ..................
Each set of drive wheels has a large, car sized electric motor to drive the wheels directly. This gives smoother power and can be regulated with the stick at the controls, just like a slot car. The electric motor in turn is hooked up to a large generator that is powered by a monstrous diesel. Some 8 cylinder, some 16. Each cylinder can be removed whole, piston and all, and serviced separate. each cylinder is almost 8 inches diameterIIIRC), inside diameter!, with a big ass piston inside.
The set up provides a very smooth application of power to the drive wheels. The locomotives have one electric motor for each set of drive wheels.
There were two locomotives on display that were actually the size of two locomotives, built as one.
For the extra pull. Now they place two together, easier to maintain and service if one goes south, just uncouple and add another, instead of the entire double engine being out of service.
It was a great tour. Anyone who appreciates big US made machinery and is in the portola area, drop on in, and if weekday, there is no one there and you can spend the whoke day with the curator on a excellent private tour with commentary.