THE SIGNAL BOX

OVERSEAS

SEMAPHORE SIGNALS
Belgian State Railways (SNCB)

by John Hinson

Upper quadrant semaphores
Photograph from the collection of Dr J W F Scrimgeour

This is an example of a Belgian two-position semaphore signal. Two-position stop signals had the German-style "blob" fixed to an arm that was more like might be found in the UK, with red arm and white stripe. The signal shows a red or green light by night.

The lower, smaller, arm is a signal for petit movement or shunting, and is coloured mauve with white stripe. This signal shows a mauve light when on and a yellow light when off.

These signals are worked on the double-wire system from the box in the background, connecting directly to the balance weights. The method of operation of the arm itself is similar to a somersault signal. The location has not been established, but the scenery points to a location in the south-east or east, the Ardennes hills.

Three-position upper quadrant signal
Photograph from the collection of Dr J W F Scrimgeour

The SNCB also used three-position signals - not as a form of speed signalling but to perform the equivalent indications of a British combined stop and distant signal. Three position signals had British-style arms without the "blob", coloured red with white stripe. The signals display a red light when on (horizontal), yellow for caution (45°) and green for clear (vertical). This type of signal was introduced in 1919. These signals are generally operated by double-wire runs operating a large pulley at the base of the mast. The movement was then relayed to the lifting rod by way of a roller on the end of a crank moving in a channel in the face of the pulley. This meant that the movement of the arm was largely unrelated to the exact movement of the wires, and maintenance simpler. This was essentially a German invention, and was also used and in Holland as qell as Germany.

Below the main arm is a petit movement arm, similar to that described above. These had provision for three positions to, but the majority worked in two positions only - this example can be detected as such because the third spectacle glass is blanked off.

The vertical indication applied for a very special purpose, at wayside stations where there was a siding into which trains could be shunted to allow trains of higher priority to pass. The Station Master would operate a special switch, allowing the signalman to clear the signal to the vertical position, displaying a green light. This would indicate to the driver the need to draw ahead and set back into the siding. The set-back movement into the siding would normally be carried out under a yellow flag from the signal box.

In operation, it was not dissimilar to the British Shunt Ahead signal, but the use of the special signal here was important in that its operation removed the train from the "Lock& Block" system when it shunted clear. Departure from the siding would be governed by a green flag and the operation of the starting signal.

The 'Y' plate is a junction indicator showing that routes converge here; all three sides of a junction would have these these.

Upper quadrant semaphore signals
Photograph from the collection of Dr J W F Scrimgeour

As discussed above, three-position signals were not used for Speed Signalling, and bracket signals were used at junctions in true British style. This type of signal, without the integrated spectacle, was the most modern design of semaphore used in Belgium, and only appeared at very large stations, such as both Brussels termini, Charleroi, Namur, Leuven, Gent, Liège etc.

The signal illustrated here shows a choice of three routes, with the centre on being the main, highest-speed, line. The main arm on this signal shows three positions, but the two lesser arms show only two indications, as witnessed by the lamp boxes mounted at the top of the dolls.

All arms are motor-operated by the 'Mors & Cie.' motors at the base of each doll. Such signals could, however, be mechanically operated by double-wire - using two adjacent levers in the nearby box. A red lever would operate the arm from On to Caution, whilst the neighbouring yellow lever would operate it from Caution to Clear. This strange situation, whereby one box actually operated the distant for another box, was resolved by the yellow lever by way of a Siemens & Haske electric block-lock. The complications of the yellow lever were avoided if the function was replaced by motor control of the distant direct from the box concerned.

The floodlit triangular plates mounted on the posts are speed indicators - place a zero after the figure and that is the permitted speed in km/h. The central one has white letters on green ground for the permitted line speed, whilst the other two are black lettering on yellow to indicate "brake to 30 km/h" etc.

Three-position distant arms were used below three-position red arms to indicate an extra slow indication (red arm vertical, yellow arm at 45°) in tow circumstances - a) the next signal was a junction bracket with the lower red arm vertical or 45°, or b) the next signal was showing red main arm at 45° AND the next signal after that was within braking distance. A stand-alone three-position distant could show the same indications.

The distant arm was distinguished by a large yellow arrowhead plate on its end. At 45° it displayed a twin night aspect of yellow and green horizontally. The green light was produced by a mirror in the middle of the lattice post shining through a fixed green lens. In the 'caution' aspect this was obscured by the rightmost blank aperture in the 'arc' spectacle. The same blank obscured the main yellow light in the vertical 'clear' aspect, leaving one green light. Latterly the mirrored light was replaced by a fixed green searchlight in the post.

In the background of this view, a three-position signal can just be discerned in the background in the fully-off (vertical) position. At any such signal that acted as a distant signal (i.e. showed all three positions), countdown markers were provided - two of the three for this signal can be clearly seen on the right.

Disc signal
Photograph from the collection of Dr J W F Scrimgeour

This revolving board signal is in fact a true French Carré and is probably violet on colour. One sizeable private railway company, the Nord Belge, used French signalling and this possibly shows a station on that railway. The Nord Belge operated the main Erquelinnes - Charleroi - Namur - Liège Longdoz line; this was the French 'Nord' trying to establish a direct route to Cologne and Berlin. The NB used rather antiquated 'carré' boards with the lenses and lamps incorporated in the board as seen here, whereas more modern French boards used separate spectacles to avoid lenses breaking by the violent shock occurring when the board slammed shut.

Additional notes by Michiel Rademakers



Comments about this article should be addressed to John Hinson