Signalling Q

[Nick_Burman]

Hi all,

 

Before the widespread use of colour light signalling, CTC and suchlike, the JNR and some private railways used a form of signalling system which I dubbed the "half-interlocking" (don't know it this would be the correct term, though). In this system the signals were actuated from a ground frame or signal box, but the switches were thrown from ground throws. Signals and switches were interlocked using sliding plate locks fitted next to the switches and tied in to the signalling cabling. Now, for the questions...

 

- Was this system a Japanese invention, or was it derived from British practice? I seem to remember the existence of similar systems in Argentina, on the British-owned railways there;

- What were the considerations behind using such a system instead of a full interlocking (with both switches and signals locked and actuated within a signal box)? What kind of locations would have gotten such signals?

- In the attached picture (Suzaka on the Nagaden if I can remember well), there are four levers with triggers, were these switch levers and where was the interlocking done, on the frame or by the switch?

 

 

 

Cheers NB

[marknewton]

G'day Nick,

 

You've raised some interesting points, I can answer two with certainty, and make some educated guesses about the rest.

 

The style of interlocking you describe is of British origin, and can also be found in Germany.

 

I suspect there are a number of reasons for using such an arrangement. Economy, local weather conditions - particularly snow, and local working arrangements - station staff responsible for working trains through the station, train crew responsible for shunting. But without knowing a lot more about Japanese safeworking practice, I couldn't say anymore with certainty.

 

At first I assumed the four levers in the picture with catch handles are point levers. I noticed that the other levers have a shackle at their base that the signal wire can be seen attached to, so from that you'd assume that the locking was done by point detectors. But I'm not 100% convinced - 11 signals seems an awful lot for only four points. Also the numbering of the levers doesn't make a lot of sense to me. I wonder if the levers aren't releases for ground frames elsewhere in the yard? What we need is someone who can translate the text on the levers... 

 

All the best,

 

Mark.

[bikkuri bahn]

The "half interlocking" you describe was called "type 2 interlocking".  The interlocking with both point and signal levers together with interlocking equipment either in a dedicated box or a designated area on the station platform was called "type 1". I reckon type 2 was used on secondary and branch lines, where the traffic didn't warrant a full signal box, and the signal and point control could be done by regular station platform staff (in the case of a remote rural station, the stationmaster only).

 

As for the picture, the levers are for departure, home, and distant signals.  There appear to be two departure and two home signal levers for both up and down lines, plus a distant signal lever for the up and down line respectively.  I can't read one label.  Up line levers are closer to the camera, down line far side, however, the #1 down line departure signal is closest and separated from the other signal levers.

 

Type 2 interlocking, Inbi Line, Tsunoi Station (likely this station used spring switches):

[Nick_Burman]

The "half interlocking" you describe was called "type 2 interlocking".  The interlocking with both point and signal levers together with interlocking equipment either in a dedicated box or a designated area on the station platform was called "type 1". I reckon type 2 was used on secondary and branch lines, where the traffic didn't warrant a full signal box, and the signal and point control could be done by regular station platform staff (in the case of a remote rural station, the stationmaster only).

 

As for the picture, the levers are for departure, home, and distant signals.  There appear to be two departure and two home signal levers for both up and down lines, plus a distant signal lever for the up and down line respectively.  I can't read one label.  Up line levers are closer to the camera, down line far side, however, the #1 down line departure signal is closest and separated from the other signal levers.

 

Type 2 interlocking, Inbi Line, Tsunoi Station (likely this station used spring switches):

 

Thanks once more BB. In the case of Suzaka, until a few months ago it was a 3-way junction, with single-track lines radiating to Nagano, Yashiro and Yudanaka. So it would have required 3 distants (one for each approach), 3 homes (ditto) and 3 starters, which would account for 9 signals, leaving 2 unaccounted levers.

 

Cheers NB

[Guest Closed Account 1]

So are there different signals to use for main lines and yards or can one use a single target 3-color LED searchlight style lollipop throughout the layout?

 

I would choose a model with a 2-sided head to view it from both directions.

 

Any preferences to brands?