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The original signalling on the line was rather primitive and
reflected the origins of the northern and southern sections, the Somerset
Central and Dorset Central Railways respectively.
The Somerset Central, as a broad-gauge line,
and one which was confidently expected to fall into the Great Western
empire, was signalled on standard Brunel practice with disc and crossbar
signals exactly like those used on the Bristol & Exeter Railway and on the
Great Western itself.
Display of the red disc facing the train was the proceed signal. The signal
turned through a right angle, to place the disc edge-on and display the
crossbar at right angles to the track, this was the stop indication. These
disc and crossbar signals were used throughout the Somerset Central portion,
from Burnham to Cole.
 The
Dorset Central section of the line took on a London & South Western Railway
influence. A slightly different type of disc signal was used. In the danger
position a red half-disc was shown to the driver, only the upper half of the
complete signal. The outer periphery of the circle was continued round the
bottom half, but the interior portion below the horizontal centre line was
open. In the proceed position the disc was turned edge-on, and virtually no
positive indication of a clear line was shown to the driver.
The distant signals on the Dorset Central part of the line, when they were
introduced, were of similar construction to the stop signals except that the
division between the red half-disc and the open portion was made on the
vertical centre line, instead of the horizontal, and the left-hand portion
was red, with the right-hand portion open.
On the single-line sections there were
certain stations having no passing loops. These came in the middle of
single-line block sections, and were not equipped with signals of any kind.
The scheduled stops at some of these stations were conditional only, and
after the introduction of semaphore signals some of the old disc and
crossbar signals were installed at these intermediate stations to indicate
when a station stop was required to pick up passengers or goods.
The last remaining signal of this type was at Spetisbury station and was
removed around 1901.
After the setting-up of joint ownership, the
London & South Western Railway took over responsibility for civil
engineering and signalling, and standard LSWR semaphore signalling practice
became established. While many wooden posts remained until the grouping era,
the majority of the actual masts were of the standard South Western lattice
pattern.
In Southern Railway days when there was an acute shortage of steel, many of
the older posts, when due for renewal, were replaced by a new standard type
developed on the Southern, using two old rails braced together.
Gradually the old LSWR semaphores were replaced by modern upper-quadrant
arms. In the last few years of the line's operation a few Great Western type
semaphores were erected as replacements - the down starting signal at
Midford, for example, and the down distant at Masbury.
Backing signal at Masbury station
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Between Midford and Combe Down Tunnel
were some unusual signals. These were 'Backing Signals' and were put in
place to enable drivers of heavy freight trains who were unable to
continue the steep climb through the tunnel to safely reverse back down
to Midford.
The driver would stop his train short of the tunnel entrance and call
the signalman in Midford box on the lineside telephone to advise him of
the problem. The signalman would then 'pull off' the backing signals,
thus authorising the driver to reverse back down to Midford station,
passing on his way the down home and starting signals at danger. The
train would then either take another run at the bank, or summon
assistance from Bath Shed if required. |
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The tablet-exchanging apparatus used on the Somerset & Dorset was designed
by Alfred Whitaker during his term as locomotive superintendent of the Joint
line. (British Patent Specification No. 861 of 1905).
 On
the engine was a combined 'deliverer' and 'receiver'. When out of use this
was close to the side of the engine and was pushed out when required. The
tablet to be given up was placed in a leather pouch with a steel ring,
carried at the rear end of the apparatus, and kept in position by a spring
clip. The receiver consisted of a gunmetal jaw with two triggers in the
front and with a rubber pad at the back.
At the lineside at the tablet station were mounted the familiar standards.
The jaws of the apparatus on the engine engaged with the loop of the tablet
pouch carried on the lower arm of the standard, and a similar receiver on
the upper arm of the standard seized the loop of the tablet pouch from the
engine. The arms of the standard were normally parallel with the running
line, and were turned to a right angle with the line by the signalman when
putting out a tablet ready for exchange. The standard was provided with two
bevel wheels, but these had teeth on only a quarter of their faces and were
provided with a stop to prevent them moving further than the correct
distance. When that point was reached, the weighted lever was slightly past
the perpendicular. The shock given by the receipt of the tablet into the
receiver was such as to throw the weight over the centre. It then fell, and
the bevel wheels turned the standard so that the arms were cleared of the
running line. This was a very good feature, and the apparatus in general
gave excellent service with speeds of exchanging sometimes even in excess of
60 m.p.h.
The margin of error was limited with a pouch
loop of such small diameter. When the apparatus was fitted on the tender,
variations in height caused by weak springs or track insulations which
caused the tender to roll at the critical moment would result in a 'miss'.
Drivers were always prepared for this with a hand raised toward the brake
handle. If the enginemen were smart, very little loss of time occurred by
the fireman having to turn back for the tablet after stopping.
In placing the tablet into, or removing it from, the engine catcher, the
fireman had to expose himself to some danger, but in the history of the line
there was no record of anything worse than a badly bruised arm sustained by
a fireman who had left his action so late that he was struck by a lineside
catcher.
The apparatus fitted to the near-side
of a locomotive tender.
To ascertain whether the catchers were
correctly aligned, a locomotive inspector on the engine would insert a
circle of cardboard into the pouch hoop prior to delivery from the engine.
The cardboard was secured to the end of a length of string by which it was
drawn back on to the footplate after delivery of the pouch; the cardboard
would then bear an imprint showing where the lineside catcher had struck it,
and if the imprint was not central, the catcher had to be checked with a
special gauge.
Engines not fitted with catchers had to exchange tablet pouches by hand, in
which case the code word 'POUCH' was relayed to all signalmen, who then made
use of the pouches with large hoops. Bath locomotive department kept a stock
of clamp-on catchers which could be fitted at short notice to any engine
arriving from the North which had to be pressed into service over the S&D. |
