My Austrian type 12SA lever frame: Locking the distant signal

Here is the last lock type of the 12SA interlocking: The simple lock between a home signal and its distant signal.

Of course, the distant signal had to remain in the "stop" position as long as the home signal was also not "clear." This rule was enforced by a simple bolt that moved into a hole either in the chain wheel of the home signal lever or of the distant signal lever. Here is a short video that shows how the home signal and then the distant signal is moved to "clear:"

• First, the home signal lever is reversed.
• Then, the small bolt is moved to the right with a small lever. Now, the home signal lever is locked, and the distant signal lever is free to move.
• Finally, the lever of the distant signal is reversed.

Clearing home and distant signal

Here is a sequence of images showing the same operation:

Normal position

Clearing the home signal

Clearing the home signal

Clearing the home signal

Reversing lock lever

Clearing the distant signal

Clearing the distant signal

When the signals are returned to their normal "stop" and "stop expected" positions, the levers are moved the other way round:

Returning distant and home signal

On my 12SA, similar locks were also used between the fouling bar levers and the home signal levers. This was necessary so that the electric lock (described in the previous posting) would have to be engaged before the corresponding home signal could be cleared.

On small signal lever installations, this sort of lock was also used to prevent that the opposing home signals could be cleared at the same time. Here is an example from the small town of Horn in Lower Austria, where home signal A is "clear," while the lever of home signal Z is locked in the downward "stop" position:

Home signal levers, Horn, 20.9.1986