THE SIGNAL BOX

BLOCK SYSTEM

BRITISH RAILWAY SIGNALLING INSTRUMENTS

Great Northern Railway signalling instruments

Great Northern Three-Wire Three-Position block

Great Northern Three-Wire Three-Position blockUnlike many of the impoverished pre-grouping railway companies, the Great Northern never made ant attempt to economise in telegraph wire by using the complexities of one-wire blocks. Instead, they created their own style of three-wire system, many of which were built out of old telegraph instruments.

On the left is a pegging instrument, a straight conversion from a telegraph instrument by providing a pistol-grip trigger device to hold the commutator to the left or right.

The right-hand instrument is the non-pegger for the opposite line - here the base section of the telegraph instrument has been omitted as unnecessary.

Between the two instruments is the bell - which was encased in a timber box for neatness.

The example illustrated is at Blotoft Siding, more details of which will be found in the Photo Galley.