Perculiar Position Lights Signals

[Skoodle]

I wonder if any of you knowledgable chaps could help me. Travelling on the up between West Drayton and Hayes & Harlington are three unsual signals I haven't seen before. They are marked Z1, Z2 and Z3. They appear to have a collection of 9 position lights, each with their own shroud and are at main signal height, so not GPLs.

They are situated such that there are eight in a circle, like a clock, with the ninth in the middle. I've been meaning to ask for quite some time yet never have! It really has bamboozled me as in all my training and rule books and even RailSigns.co.uk I haven't been able to find what they are!

 

[kestrel]

They are shunting signals for the trains unloading stone at stockley

they flash 45% to the right to shunt fwd, 45% to the left to set back, and 3 reds to stop

 

[Pete2210]

Kestrel, that stone terminal at Stockley, is it classified as being Hayes or West Drayton or just Stockley?

 

[dk1]

I know Barham sidings near Ipswich has one.

 

[Metroland]

They are creep signals, commonly found at power stations, collieries, quarries and the like for low speed unloading/loading.

See http://www.railforums.co.uk/showthread.php?t=5290

 

[Skoodle]

Brilliant response gentlemen! Thank you very much!

 

[9K43]

I have loaded/unloaded trains under these token signals on many occasions, mainly at pits in and around West/South Yorkshire and sand at Monk Bretton Glass works.
As there are very few pits, loading/unloading is done with back to back radios.
The only token signals are in the Power Stations, eg Drax,Eggborough, Ferry Bridge.
Sand is discharges at Selby Potters using radios to stop and start the train.
If using radios to stop and start correct safety critical communication must be adhered to at all times.