GWR FPL crank arrangements c1905

[Chrisbr]

I have the following snip from a picture of GWR point work and am trying to understand what cranks (not visible under the FPL cover of course) would have been used to convert the transverse movtion of the FPL drive rod (top left) into the fore and aft movement needed for the Facing Point lock plunger and also the Lock Bar (top right)...

Did the GWR have such a thing as a "T" crank, or would it have been a standard crank in conjunction with a reversing crank? If the latter, how were both cranks attached to the Facing point lock plunger?

 

[RailWest]

The important thing to remember is the the rod from the FPL lever did not drive the FPL plunger directly.

 

The rod drove the end of the lock bar further from the plunger (the linkage for which can be seen in the photo) and the end of the bar nearer to the plunger then drove the plunger. This ensured that the plunger did not move if the lock bar was broken.

[Chrisbr]

Chris,

 

Thanks for responding and while I understand later practise was to connect the FPL lever to the far end of the lock bar and the plunger to the near end, as you say, providing confidence that the lock bar was functioning as designed, this early example does not seem to follow that practise. A wider snip shows no connection to the lock bar at the far end and having played with the contrast etc. of the original scan, I can see no evidence of a rocking shaft or other connection to the lock bar closer to the FPL itself.

The only possibility is the dark shadow right at the end of the bar, but that seems too close to the end to me and more likely to be the edge of the sleeper exposed?

Chris

[RailWest]

Curious....

I don't suppose by any chance this is one of the examples of an 'economic' FPL? Do you know the location?

[Tim V]

This is what I remember!

 

[Chrisbr]

Chris,

It's the original station at Wilmcote, the points lead off the single main line to sidings for the station and local Lime/Cement works. There are two rods coming from the Signal box, one driving the switches and one the FPL, so don't think it's an economic FPL variant. I have since discovered the original negative is held by HMRS so will endeavour to obtain a copy, but that may take a while in the current circumstances.

 

Tim - yes that is similar to various other sources I have seen, but doesn't seem to fit the early example above, as far as I can make out....

 

Chris

[The Stationmaster]

One method - although I don't know if it was installed by the GWR - was to use a T crank as illustrated part way down this page -

 

https://www.rmweb.co.uk/community/index.php?/topic/14463-facing-point-locks/

 

What I cannot ascertain is who installed the signalling on the original single line.  There was a signal box (according to OS maps) at Wilmcote before the line was doubled but I can't find a photo showing it.  The second 'box built was opened in 1907 so would in any event post date that photo and in any case did not control any facing points.  The first signal box is not shown on the 1885 version of the OS map but is shown on the 1904 edition; the GWR had absorbed the line in 1883 but it is possible that McKenzie & Holland (or another contractor?) provided the first signal box and signalling equipment and thus used their design and arrangement for operating the lock bar and FPL bolt.  

 

But maybe the GWR had an earlier method of doing the job which did not ensure that the locking bar operated the FPL bolt?

 

 

[Chrisbr]

Thanks for the link Mike, some interesting material there. I can find only one more photo (strange how hard it is to find decent detail shots of FPLs and lock bars...) of Dunkerton in the early 20s with a similar looking arrangement, only this time you can see standard cranks on either side as the photo was taken from the 4ft.

It looks to me as if the FPL rod from the box is connected to the cross rod between the two cranks under the FPL cover. So not unique, but certainly not common by the time photographers were recording the scene later in the century...