Turntable Power
Hi Bill,
Early turntables and a lot of short line turntables were powered by the "armstrong" method. In other words the engine crew simply pushed the tuntable around. This was not hard as long as they got the engine "balanced" on the turntable bridge.
I've also seen turntables that were powered by electric motors. The one that used be here on the Central of Georgia was powered by compressed air from the HUGE steam driven air compressor in the roundhouse. Don't know about steampower to turn the table but it would seem logical that arrangment would have been used.
I sorta wonder if some of the more recent turntables might have been driven by some kind of hydraulic system as it would seem that it would be very efficent and powerful.
BTW...The San Francisco Cable Cars are still turned by the "armstrong method" When the car reaches the turntable at the bottom of the hill it has to be turned so that the "grip" can grab the cable for the uphill trip. Passengers are expected and encouraged to help the crew do this.