THE SIGNAL BOX

OVERSEAS

KWINANA CABIN
The last operational mechanical signal box in Western Australia

by John Hinson

Kwinana signal cabinKwinana cabin controls a yard of the same name, together with a number of industrial branches, located on the outskirts of Perth.

The structure is elevated to allow a commanding view of the yard and surrounding area. Notice the interesting contrast between the relatively modern signal box and the old-fashined signals. These are described in detail below.

Kwinana cabin opened in 1967, but the structure and frame came second-hand from Koojedda and had originally been erected in 1959. That box had not been as tall as this; additional girderwork has been added at the bottom.


An interior view of Kwinana, showing the lever frameThe cabin houses a 40-lever McKenzie & Holland frame with Cam and Soldier locking. This design predates the cabin by many years, the type dating from 1886. When the box frame were moved from Koojedda to Kwinana, a small amount of supplementary tappet locking was added.

One of the interesting features of mechanical signalling in Australia is that early technology has not been discarded in favour of more modern practices - pre-tappet locking and lower quadrant signals still predominate in areas of surviving mechanical signalling.

Notice the fact that some levers in the frame have a longer stroke than others - a feature found on most early McKenzie & Holland frames but generally subsequently discontinued in the UK. This feature can be used to allow simple signal wire adjustment necessary through temperature changes.

The lever colours generally correspond to British practice. Notice the small brass lever number plates and the "pulls" stencilled onto the side of the levers.

Please accept apologies for the poor quality of the interior photographs - unknown to me the battery of my camera was dying during this visit.


Welded lever handles at KwinanaEvidence of the lever frame's history can be seen when the lever handles are examined closely. When the box and frame was at Koojedda, some of the signals were colour-light and had the handles cut short as per British practice.

Clearly, the "waste not, want not" policy of the Signal Engineers extended to keeping the redundant pieces, which have been carefully welded on again for use at Kwinana.


The signalling diagram in Kwinana cabin. Please click on the image for an enlarged view.This view shows part of the signalman's diagram at Kwinana. Interestingly this combines the functions of illuminated diagram for the area controlled by the lever frame and panel for other parts of the layout.

For an enlarged view of this picture, please click on the image.

On the diagram, the area controlled by the lever frame is to the left - with signals, points and FPLs shown in the normal manner. The top and right corners of the triangular junction are controlled by colour-light signals and power points. Crude switches operate the signals (the red ones located in the tracks themselves) and white lights show the route that has been set. At the time of this photograph, a route had been set for a train from bottom right to top; the switches for signals 88 and 104 are depressed and the signals and route are indicated. The black-coloured switches control the points.

The layout here is of two gauges - 3'6" and 4'8½" and these are designated on the plan by the thickness of the lines. Dual guage sections (and I'm told that "mixed gauge" is a term not used in Australia) are indicated by an extra line alongside. The train signalled might be of either gauge as the entire route visible is of dual gauge.


McKenzie & Holland somersault signalThis is one of a number of semaphore signals at Kwinana, and it appears to be very much a standard McKenzie & Holland product although there are fine detail differences against British examples.

This type of signal was introduced by McKenzie & Holland in the UK following an accident at Abbots Ripton in 1876 to avoid the pitfalls of ice and snow preventing the return of a lower quadrant signal to danger. Only a few railway companies adopted this type in the UK, but in Australia there is very little else to be seen in semaphore signalling despite the unlikelihood of ice affecting the equipment.

The signal embodies the easily recognised "spike and parachute" finial of McKenzie & Holland. Mounted on a small bracket is a revolving shunt disc signal. These simply turn away from the driver for an "off" indication. Again this is technology long since abandoned in the UK.

The signal post itself is of wood, but mounted on steel girders to raise it above ground level. This isn't the result of a wood rot problem, but protection agains wood-eating insects.

Views of signals like this in the "off" position can be seen in the Bacchus Marsh chapter.


General view of Kwinana cabin and signalsFinally, here is a general view showing Kwinana cabin and the fine line of signals controlling departure from the yard.

More information on Kwinana, and its predecessor Koojedda, will be found on Chris French's web site. Recommended!


Comments about this article should be addressed to John Hinson