View single post by oztrainz
 Posted: Fri Feb 12th, 2016 10:46 am
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oztrainz



Joined: Wed Apr 10th, 2013
Location: Unanderra, Australia
Posts: 982
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Hi all,

Following on from a question raised in

Si. wrote:

Thanks John !

I think you put up a photo before of what seems like a VERY small knuckle coupler...

...low mounting as well.


This topic is planned to be mainly about "less than full size" couplings,
and I'll start with some of the knuckle types used on narrow gauge railways in Australia.

Please feel free to chime in with questions as we go along,
and to add other coupler related information from elsewhere.

This thread could get semi-technical with discussions of coupler heights,
about mounting couplers on rolling stock,
and other types of couplings used on narrow gauge railways.
You have been warned.

:P

First off what is a 'full-sized' knuckle coupler and what does it look like?

I'll pick a US-based knuckle coupler manufacturer and link to some of the pages,
relating to the knuckle coupler specifications and dimensions.

http://www.columbuscastings.com/assets/files/couplers/C-14770.pdf

This one has top and bottom shelves that stop adjacent couplers from disconnecting,
by sliding past each other vertically.

This Wikpedia page has a a good history of the development of the full size knuckle-type coupler

https://en.wikipedia.org/wiki/Janney_coupler

So much for the full-sized couplers.
On narrow gauge railways the loads being towed or shoved are less than on standard gauge railways,
so a scaled down version of the auto-coupler can be used.

In Victoria on the Puffing Billy and on the Victorian 2'6" narrow gauge network,
a 3/4 sized version was adopted in the 1920's.

The story goes that the locomotives and wagons on these isolated branchlines,
were converted from the earlier hook drawgear to knuckle couplers over a weekend.


So what does a 3/4 scale knuckle couple look like? - on a NA class locomotive:





and on a NQR gondola wagon with drop sides and ends:





Note the slot in the middle of the jaw of the knuckle.
There is a hole vertically through the jaw.

This allows a sling or a D-shackle to be attached in the slot,
by dropping a pin down the vertical hole in the jaw,
so that the pin passes through the eye of the sling or D-shackle.

This allowed the wagon to be horse-worked at sidings,
when a locomotive was not available to move the wagon.

In model terms - for On30 models of Puffing Billy rolling stock in 1/48 scale,
the standard Victorian Railways coupler height works out at the standard HO coupler height.

Dimensionally the slightly oversize standard HO coupler,
scales out at very close to the 3/4 size coupler as used on Puffing Billy in 1/48 scale.


But there was an even smaller version - to be covered in the next posting.




____________________
Regards,
John Garaty
Unanderra in oz
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