Facing Point Lock

Have you ever stopped to wonder what prevents the blades of points (correct term is 'turnout') from moving whilst a train is passing over them? It is the Facing Point Lock, or FPL as it is commonly known.

FPL These FPLs normally take one of two forms, either a lock on the blades themselves or on the bar that operates the blades. This is an example of the former and is really very simple in its implementation. After the Signalman has placed the blades where they are required he then uses another lever to move a solid steel bar into a slot on a stretcher between the blades, thus ensuring that under normal forces the blades will not move whilst a train is passing over them. Move your mouse pointer over the numbers to see the relevant functions.

photograph by Ian Morgan

The same FPL, viewed from a different angle. As will be appreciated, the FPL must be unlocked before the blades can be moved, and locked again before a facing movement may be allowed. Depending on how the Signalbox locking is set up, some FPLs are unlocked when the Signalbox lever is 'normal', and some when it is 'reversed'.

photograph by Ian Morgan

FPL The crank that operates the FPL bar. This transfers the movement through an angle of 90°.

photograph by Ian Morgan

The whole FPL installation, seen on a different turnout.

photograph by Ian Morgan


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The locking bar. In this installation this moves backwards and forwards parallel with the running rails. Two slots are cut in this bar. One for locking the blades when the turnout is 'normal' and one for when it is 'reversed'. The end of the locking bar can be seen to protrude some way beyond the slot where it locates to give a good firm locking action. These are adjusted to have a very small tolerance.