Economical Facing Point Lock

An economical facing point lock (FPL) allows a switch and its associated lock to be operated with one lever.

This page documents the operation of an economical facing point lock, using structures in the Hutt Valley area (with public access) as examples.





Temperature Compensator

Temperature Compensator.

The temperature compensator is inserted half-way between the lever or points motor and the escapement mechanism. The rods on either side of the compensator will expand and contract equally as the temperature goes up and down.

The compensator ensures that there is no horizontal movement of the operating rod at the facing point lock (FPL) mechanism.



Escapement Mechanism

Escapement. The operating rod from the points motor (horizontal, right) moves the vertical swival bar. A roller on the bar moves the escapement, which throws the points (vertical rod, right). The throw of the points is adjustable.

The facing point lock (FPL) is operated by the vertical rod (left).

The first movement of the operating rod unlocks the FPL, then the escapement throws the switch and the final movement locks the FPL.



Facing Point Lock (FPL)

Facing Point Lock. The rod to operate the facing point lock (FPL) is on the left. This rod moves continuously over the full stroke of the operating rod.

On the far right is the rectangular bar that will engage with a notch in the stretcher bar and lock the points reverse.

The middle rod, connected to the scalebeam, is connected to the detector.

On the right is the stretcher bar which has two notches for the lock. The switch throw rod moves only in the middle of the operating rod stroke.



Notched Stretcher Bar

Stretcher Bar. The stretcher bar has two notches and the sliding lock bar has two locks. When the points are operated the lock bar slides upwards in a continuous motion. While the upper lock is disengaged from the right hand notch (neither visible) the escapement throws the points, moving the stretcher bar to the right. The lower lock then engages the left hand notch, locking the points.



Last Updated: Wed Jan 30 15:49:50 NZDT 2013

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