Miscellaneous: Operating Equipment & Practices

Signalling Procedure: misc_equip249

Another extract from the ‘Great Western Railway Regulations for Train Signalling on Double and Single Lines’ detailing the operation of the Tyer’s No 9 Single Line Electric Token Block System and photographs showing both sides of the single line Key Token for the North Curve between Bearley East Junction and Bearley North Junction. The Tyer’s No 9 Key Token instrument was invented and patented by GWR Signalling Engineers Alfred Blackall and Charles Jacobs in 1912 and manufactured under licence by Tyer. It became the standard GWR single line instrument being; more compact, easier to use and with less moving parts, easier to service and repair than previous instruments. These instruments were also used on the single line between Bearley East Junction and Hatton West Junction until that line was doubled in 1939. For a photograph of the Tyer’s No 9 Key Token Instruments at Bearley East Junction Signal Box see 'gwrbj807'.

The Key Tokens were approximately 7¾ inches long and were initially manufactured from steel and later aluminium alloy. There were four possible key configurations depending on the position of the semi-circular groove cut in the key at the end of the token. The one depicted here is a configuration D. Some key tokens also had an Annett key for unlocking ground frames at the other end. When in use the Key Tokens were attached to a hoop to make their transfer easier, see 'gwrbj776', 'gwrbj786' and 'gwrhj1933'.

Robert Ferris

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