Point machine

Gradually, these were centralized and came to be operated from a signal box, either by rods, or by double wire arrangements.

Since the limitation of mechanical operation restricted the design of track layouts on the one hand, and tended to require more signal boxes, even lightly used ones, on the other hand, there has always been a desire of railway administrations to increase the distance that remote turnouts can be operated.

More recently with the increase in weight of rail, and the introduction of high speed turnouts with finer angles requiring multiple drives, points have become stiffer and beyond the capability of mechanical drives, forcing the introduction of point machines if not already done so.

The gear assembly also provides the required transmission ratio so that it can generate necessary force to move switch blades.

The latest development is to mount the switch motor inside a faux railroad tie (aka sleeper) where it is relatively hidden from damage from track maintenance machines.