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Southern Signals
Walker's Train Describer

The Walker's Train Describer consists of a clockwork driven mechanical "Sending" instrument and an electro-mechanical "Receiving" instrument. The purpose of the instruments is to send a request from one point to another with a visual indication of what is required. Each pair of these instruments has an identical dial upon which is fixed round tablets showing various required movements (e.g. Light Engine to Down Yard) and a pointer to indicate the tablet required.
In the photograph below, taken in Brighton Signalbox, are a "Receiving" and a "Sending" instrument, each of which is connected to the "opposite" instrument elsewhere.
 
Walkers Instruments The Walker's Instruments that were installed in Brighton Signalbox.

photograph by kind permission of Alan Elliott
 
The instrument on the right is a sending one, note the levers are outside the dial making the instrument resemble a ship's steering wheel! The one on the left is a receiving instrument and the bell on the right strikes once for each position the pointer passes.

When a request is sent for a particular move to be set up the person requesting it has to carry out the following procedure:-
First he will need to pull towards himself the lever adjacent to the appropriate tablet and then he has to push away from himself the lever by which the pointer is currently resting. The pointer of the "Sending" instrument will now run around the dial until it reaches the lever that was pulled and then remain in that position. The "Receiving" instrument at the other end of the circuit will step on in unison with the "Sending" instrument whilst the bell will sound one beat as it reaches each tablet. If the destination tablet occurs less than five points from where the pointer is resting then the mechanism and pointer must be allowed to travel a complete circuit of the dial to the "new" description. To do this the levers are worked in the opposite order so that the lever adjacent to the appropriate new description is pulled out after the pointer has passed that description.

Upon receipt of a destination (other than "Cancel") the person receiving must acknowledge the receipt by sending the appropriate number of beats on the bell key regardless of whether or not he is in a position to make the described movement. Upon receipt of the "Cancel" indication, the person receiving will acknowledge by one beat on the bell key.

As with all things mechanical, it does sometimes happen that the two instruments can become out of phase. In this situation the instruments concerned should not be used until such time as an engineer has corrected them!

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This page was created 3 July 2004

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