Railway Turntable - Overview

Overview

Most turntables consisted of a circular pit in which the bridge rotated. The outer ends of the bridge were typically supported by a rail running around the floor of the pit, supplementing the central pivot. The turntable bridge (the part of the turntable that included the tracks and that swivelled to turn the equipment) could span anywhere from 6 to 120 feet (1.8 to 36.6 m), depending on the railroad's needs. Larger turntables were installed in the locomotive maintenance facilities for longer locomotives, while short line and narrow gauge railroads typically used smaller turntables as their equipment was smaller. Turntables as small as 6 feet (1.83 m) in diameter have been installed in some industrial facilities where the equipment is small enough to be pushed one at a time by human or horse power. Indeed such small turntables, called turnplates, were common on the early horse-drawn mine railways before the development of the steam locomotive, and were widely used for marshalling wagons and carriages in the goods and passenger stations of the earliest steam railways.

Turntables will have a positive locking mechanism to prevent undesired rotation and to align the bridge rails with the exit track. Rotation of the bridge could be accomplished manually (either by brute force or with a windlass system) by an external power source or by the braking system of the locomotive itself, though this required a locomotive to be on the table for it to be rotated.