The New Zealand Railways Magazine, Volume 2, Issue 7 (November 1, 1927)
Facing Point Locks
Facing Point Locks.
On all train running routes, at interlocked stations facing points are provided with a lock consisting of a plunger which locks the switches in either position as required before the signal governing that route can be set to clear.
A bar lying parallel to and alongside the rail is part of this lock, and this bar is required to rise above rail level in the act of locking or unlocking the points. It is long enough to cover any vehicle wheel base and so the points cannot be unlocked while any vehicle is passing.