Sydney Live Steam Locomotive Society

Exterior of SLSLR West Signal Box

The levers are similar to the full size Westinghouse miniature lever, except that they are spaced at 2 inch intervals rather than the 2½ inch of a full size installation, in order to be able to fit the required number in the space available. Below the quadrant plate we have rearranged the casting to provide two plates for adjusting screws that directly contact a double pole double throw toggle switch mounted directly below the lever. 48 levers are provided, the signal levers being red, the point levers being black and other levers (closing levers) in blue. There are no spare levers.
Picture above by kind permission of © Warwick Allison

closeup of the westinghouse style levers in the signal box

The lever pattern, trigger and latch rod, and quadrant plate were all cast in aluminum from patterns made by the members.  Other parts required were machined to suit. All indications are provided on engraved traffolyte plates mounted behind the levers. While these plates are more typical of a modern route setting installation, they contain the usual indications provided in a power box as follows: Points normal and reverse (yellow LEDs), free (green LED) and transit (flashing red LED). Signal reverse (green LED). The switches used for points have a centre off position to cut off power when detection has failed to do so and to facilitate repair during failure.
Picture above by kind permission of © Warwick Allison

closeup of the westinghouse style levers in the signal box

There is no track circuiting although mainline signals are replaced to stop by the train passage through flange contact with a trigger wire that sends a pulse to an electronic detector. To reclear the signal, the lever is placed normal and then reversed again. The same mechanism is used to provide a degree of track locking to points so that they are not inadvertently pulled under a train. A 7 second timer is applied to the points locking once the signal is replaced by a train. This has proved to be quite successful in protecting against signalman’s errors.
Picture above by kind permission of © Warwick Allison

geberal view of the lever frame comprising of Westinghouse style miniature levers

 

 

 

 

 

 

 

 

 

 

 

 

geberal view of the lever frame comprising of Westinghouse style miniature levers along with the track diagam mounted above the window

 

 

 

 

 

 

 

 

 

 

 

 

 

All functions are directly interlocked electrically. Because separate levers are used for each route, and no overlap interlocking is provided, no conditional interlocking was needed which simplified the circuit design. However recent expansion has resulted in two ‘A’ & ‘B’ signals being provided (selected by points) and hence some conditional interlocking.

Point controls are polarized, as is detection, resulting in only four operating wires per machine. Point machines are electric motor operated with separate detection provided on facing points only.
Picture above by kind permission of © Warwick Allison

track diagram of the Sydney Live Steam Locomotive Society

A CAD produced paper signal box diagram is provided showing all tracks and signals in the NSW pattern as provided for a non power box. Picture above by kind permission of © Warwick Allison

the signal box in use.

Picturd above, are signal men Vic Scicluna, seated left and and Mark Gibbons on the right operating the signal box..

The system was progressively brought into use from the early 1990s. Detail of the railway and additional information on the signalling and circuit arrangements is on line at www.slsls.asn.au

Picture above by kind permission of © Warwick Allison

relays in th relay room

Local detection relays and signal control relays are located in equipment cupboards local to the equipment, while point detection and signal normal functions are located in the signal box. All relays are telephone type or cradle type. While the design follows fail safe principles, all equipment is essentially non vital. All equipment is 24v DC.

All text by Warwick Allison, Picture above by kind permission of © Warwick Allison