Wednesday, 16 October 2013

Power Poles

The NSWGR recycled old rail for fences and power poles along the full length of its right of way. Ray Pilgram provided a series of photographs showing a series of line side power poles in various locations and while all are of a similar construction but there are too many variants to cover in this article.

Pole Construction


3D Solid Model Rendered Image 

The image for the cross arms was extracted from a Ray Pilgrim photograph taken at Werris Creek and clearly shows the arm construction allowing the 3D model to be created and the parts sent out for rapid prototyping. The model is about 25% oversize to allow the detail to be reproduced and to allow urethane casting. A separate photo of the Silver City Comet taken in the 80's out west provided a template for the poles.  

Technical Notes
Ray Pilgram on his Bylong Blog has posted some PDFs on the technical detail related to the installation of telephone poles on NSW Railways plus some additional notes of interest

The main document "Line Route Maintenance & Construction" has all the relevant details for those seeking to construct the rail based poles. There are another series of manuals for wooden construction on the same site for those seeking an alternative to rail. 

Cheat Notes:
The relevant points for modelling are listed below

Minimum rail length 30 feet [9 meters]

Spacing 165 feet [50 meters]

Standard cross arms are either 6 pin or 8 pin

The base of the rail faces the running track

The cross arm faces the Sydney side of the line except where wire stays are required and it can be varied for this

Cross arms for 6 pin are 3'' x 3'' x 5,-3'' [75 x 75 x 1600] - Timber tallow wood.

Cross arms for 8 pin are 3'' x 3'' x 8,-3'' [75 x 75 x 2500] - Timber tallow wood.

For complete detail link to Ray Blog and review the manual linked above.

Model Construction
Code 100 rail was used for posts cut 280 mm long [40 scale feet] with a etched brass V and urethane cross-arm with Peco pins rejected for spiking used to pin the V to the arm and rail. The spacer between the base of the V and the rail face is a length of 1/16'' diameter Styrene is drilled 0.020'' [0.5] and a Peco Track pin pushed through. 

All the rails and etches were sprayed using Tamyia Red-Brown with the the cross arm painted in Tamyia Sky Grey and finally the insulators with Hombrol Gloss White Enamel. This should be done before assembly. A alternative is gray for the V to represent galvanized finish - White Knight SLS primer is perfect and need no additional painting. 

The wire will be simulated using Berkshire Junction EZ Line heavy green between the poles. The green was selected as it provides a superior effect to other colors with the light catching the line in a most realistic manner when installed. The main feature of this line is its elastic construction preventing small strikes breaking the line with the disadvantage begin a lack of catenary sag but in service this has proven to be a practical sacrifice. An alternative is to use 0.010 [0.25 mm] CMA phosphor bronze wire that can be purchased on special order from the Model RR Craftsman.

The poles on Spicers Creek are set at 27 - 30 feet above track and at  120 - 150 mm from the edge of the running rail. The centres are set at 700 mm [100 scale feet] to give a sense of distance while reducing the load on the poles. On curves the poles have to be closer due to restriction on space and the tight radius of model curves [1625 mm] which if not allowed for will create a chunky appearance. The module the poles were positioned visually to provided a suitable appearance in the module. The elastic wire will require the addition of a stay at the last pole in each module. On the Spicers Creek the start was terminated in the styrene backdrop and in between the poles the loads cancel out.


Nicholas said...

Good someone is rebuilding the old telegraph lines. I am interested because of the insulators.

Nicholas said...

Good someone is rebuilding the old telegraph lines. I am interested because of the insulators.