THE SIGNAL BOX

OVERSEAS

RIO TINTO MINES
(MINAS DE RIO TINTO)
Rio Tinto Railway

by John Hinson

General view at Rio Tinto Mines showing two signal boxes
Photograph by Dr. J W F Scrimgeour 9/69

The whole purpose of the Rio Tinto Railway was, of course, to serve the zinc mines of that name, and this view captures the general air of tiredness exuded by the railway in 1969. Pictured here are two of the three boxes that existed at the mines. That in the background controls the "main line" through the mines, which drops steeply down to pass the passenger station (which is out of view to the right) before continuing on its way. The box in the foreground serves the yard area.

View looking down the main line past the back of the yard box
Photograph by Dr. J W F Scrimgeour 9/69

This picture was taken from behind the yard signal box - notice how the steep gradient has brought the track up to a level that makes the yard box in the previous picture look as if it is a ground-level structure.

In the middle distance, alongside the connections to the yard, is the unimposing passenger station served mainly by a loop but with a face against one of the two main lines. A train is just leaving the platform.

General view of main line with subsidiary box on left
Photograph by Dr. J W F Scrimgeour 9/69

Taken from roughly where the passenger train is, in the previous view, this picture looks on down the line, past yet more signals. Some of the semaphore signals appear to have colour light heads attached to them - and a close examination of this and other pictures also reveals some such signals on their own post. This was possibly a sign of forthcoming resignalling.

On the left is the third signalbox, described as a "subsidiary box". This presumably means it was worked as a ground frame under the supervision of one of another box.

Lower quadrant signals at Rio Tinto Mines
Photograph by Dr. J W F Scrimgeour 9/69,

A view from the yard box window allows close examination of the two three-arm signals which apply to the main lines to the left of the cameraman - it is thought that each post applies to one of the two lines. All show signs of splitting timber in the arms, and most have rings (or remains of) attached to the other face.

Notice that the signal lamps are not mounted inside the post like most Spanish and Italian semaphores, but to one side in more conventional fashion. The lenses in the egg-shaped lenses in the spectacles resemble Stevens & Sons' build. The signal posts appear to be made of iron.

Thirteen arm gantry signal at Rio Tinto mines
Photograph by Dr. J W F Scrimgeour 9/69

The five-doll signal gantry opposite the station, where the yard lines diverge, carries 13 arms in total.

The main signal box at Rio Tinto Mines
Photograph by Dr. J W F Scrimgeour 9/69,

The lofty box controlling the upper end of the station is seen here, looking quite decrepit. The rectangular black plate attached to the corner of the box carries a which which may be used to lower a train staff for a single line, or maybe just to bring the signalman's coal bucket up!

The row of signals look to be attached directly to the bridge parapet, which is an unusual arrangement. The unlit colour-light signal in the foreground looks so rusty that it suggests the resignalling scheme for which it was intended has been forgotten.

Interior of the yard signal box
Photograph by Dr. J W F Scrimgeour 9/69

Inside the yard signal box, an altogether different picture is presented. The highly polished brass makes the box look well-cared for and is a particularly creditable given the dust and dirt that naturally accompanies any mining area.

The lever frame is a standard McKenzie & Holland model, complete with a full set (apart from the spare levers) of their style of oval brass description plates.

The block instrument, with bell mounted above, is manufactured by Powles & Moore and described below.

Powles & Moore block instrument
Photograph by Dr. J W F Scrimgeour 9/69

The Powles & Moore block instrument works on the One-Wire Two-Position principle, combining the simplicity of the similar Tyer's with the advantages of Harper's equivalent. The indications are given by two miniature signal arms inside the case, and operated by the depression of the single bell plunger. Around the plunger is a commutator handle which rotates through 360° to show "Line Blocked", "Line Clear" and "Train on Line" which gives the signalman at the accepting end the three indications used on three-position block.

A delightfully antique-looking telephone hangs on a hook on the side of the instrument, allowing the single line wire to also be used for communication with the adjacent box.

The brass plate reads:

POWLES & MOORE PATENT
RIO TINTO RAILWAY CO. LTD.
(remainder undecipherable)

No evidence has so far been found to suggest whether these instruments were ever used by other railway companies anywhere in the world, nor whether the instruments are a British product.

About the photographs



Comments about this article should be addressed to John Hinson