Can anyone tell me how a turntable works

yea im doing a project on how to turn a train around well i know you use a turntable or a looped track but can anyone tell me how a turntable works

…A rotating device long enough to contain and support a steam engine and tender and supported on each end with wheels resting on a circular track [single], in a round pit. Device is supported in the center so it can rotate. Engine enters from an approaching track and placed on the turntable and the turntable is rotated by a power source and directed to whatever stub track the engine will be directed to…Such as into a stall in a roundhouse.

QM

How about a wye?
Ed

A turntable is a really simple idea once you start thinking of it in comparison to other parts of the railroad. A turntable is in essence a bridge which rotates around a central axis. To start off you make the turntable pit which is just as simple as it appears, a big cement lined hole in the ground. You then take rail and make a loop inside the pit which is what the table sits on. Then you take what is essentially a bridge and depending on the weight rating add flanged wheels only on the ends for a two point bridge or add a bearing system in the center for a three point bridge. These wheels are angled appropriately to match the radius of the turntable pit rail. Then it is just a matter of connecting electric motors to the wheels if if is that modern, (early and or lightweight turntables were turned by hand). The controls for these motors are mounted in the small cabin or shack mounted on the side of the turntable bridge. The power for the motors usually is routed through a set of contacts on a A-frame over the locomotive. The last detail is a system of a locking mechanism to align the table with the roundhouse leads so that the bridge doesn’t move with a locomotive on it.
Hope this answers your questions,
Connottonvalleyrr
Connottonvalley2652@hotmail.com