Point rodding

Posted on March 20, 2015. Filed under: Project progress |

“Write out a hundred times, boy: ‘I must not add ballast and scenery before point rodding’ ”.

Fortunately (thanks, Ian, for the prompt), I made the Up platform removable. The 3-way point rodding runs from the signal cabin on the Down side, across the main lines to a trio of cranks which transfer the drives southwards alongside the Up Platform. One rod drives the fouling bar, which must be raised to allow the Up Starter to be pulled off, and the other two continue to the south loop point and the associated facing point lock.

??????????       Plain cranks

I have no photographs showing the operation of Culrain’s points. I sketched a plan of the south loop point from a published 1960 photo of the equivalent point at Tain and combined this with point photos I took at Dunkeld in 1990 and of Keighley and Worth Valley LMS points in 2006. A chequered steel protection plate covers the most difficult parts to make, but getting the rods to line up in plan, and in height, also looked daunting. My solution was to make a sub-assembly of the two adjustable cranks (one to operate the point and the other the facing point lock) and the detector (one slide from each of the point switch blades, which prevent the Down Home signal being pulled off if either of the blades are incorrectly set). The sub-assembly on its card base will be positioned as a unit on the layout and the rods soldered to the cranks.

Scenery 17 150320       South loop point mock-up

I made extensive use of Steve Hall’s excellent articles in MRJs 113 and 115. I am grateful to Steve for his suggestion on how to scratch build the detector, which I set to show the point normal and the Down Home On. I laboriously scored a strip of nickel silver to represent chequered steel plate, modelling the whole unit with its supports on the one at Tain. Other etchings were supplied by Brassmasters (cranks) and MSE (crank bases).

I removed the rodding seen in the photo in February’s “Monthly progress” because it wasn’t level, and decided to make the above items before trying again to install the complete rodding assembly. Let’s hope it goes better this time.


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