N Scale Transfer Table?

[Sumpter250]

You can do the same thing with a Tortoise motor.

Tortoise motor, as in the switch machine?, or is this a motor with a high reduction gearbox.
I know the cable system I described is a bit complex, but it can move a "carriage" reliably, and precisely, and, for one of the few times in my life, I can't visualize how a tortoise motor would move the bridge of a transfer table. I know I'll smack my forehead with the palm of my hand, and say Duh, of course!,once it is explained, but at this point I really can't see how it can be done. If you would be willing, an explanation would help.