MODELLING THE LYNTON AND BARNSTAPLE

 

Scale Couplings
by Bob Barnard

History

The L&B's engineer specified the heavy Jones-Calthrop chopper couplers for the line; whilst these would have been appropriate for a 2ft 6in or metre gauge line, they were arguably a bit of an overkill for the 2ft gauge L&B.

Very early on, the L&B removed the hooks that had been supplied by the builders on the rear of locos, and on one end of all rolling stock, and all stock thereafter ran with hooks only on the "Lynton" end.

A drawing showing the L&B coupler, with its key dimensions, is shown below:

Sketch by R E Tustin (MRC early 1950s)


Lew’s front coupler


The “Barnstaple end” coupler on a 4T open wagon

Modelling

K’s Couplers

When I started modelling the L&B in 009 scale in the 1960s, K's sold a range of whitemetal components for modellers, including some items for the then quite new

009. As these included a pack of castings for the correct L&B chopper couplers, my choice of couplers was simple.

Each set of the K's couplers consisted of a pair of cast coupler bodies, and a cast hook. The bodies were slightly over the scale width, in order to accommodate overscale thickness hooks, and the coupler heads were a bit on the small side. One of the bodies, and the hook needed drilling, and a small piece of wire then attached the hook. The coupler shanks were also drilled, and were pinned to the vehicle bodies a few mm behind the buffer beam.

The couplers worked well on my first rolling stock - 4-wheeled open wagons and vans, and I found that no pivoting was needed to cope with curves.

On bogie stock, the couplers were pivoted, leaving the coupler able to swing from side to side a little in a rectangular slot in the buffer beam.

I found that the cast coupler bodies could be bent up or down a little to adjust their height, ideally so that coupler bodies with hooks were very slightly lower than the non-hook ends, helping them to remain coupled when running over rail joints and pointwork.

Scratchbuilt Couplers

I worried that the white metal couplers would get damaged over time, so I decided that I would fabricate couplers for locos from nickel silver. Different pivot arrangements were necessary on some locos, as lead weights on leading trucks filled the space immediately behind the buffer beam, and some locos have spur gears immediately behind the rear buffer beam. In these cases, a small "pocket" of NS strip was soldered on the outside of the buffer beam, and drilled to take a wire pivot for the coupler. This is not the ideal location for the pivot, especially at the rear of locos, but it works quite well on my 18 inch minimum radius curves.

Early Experience

Coupling two vehicles involves manually lifting the hook (if necessary), lining up the coupler bodies, and then lowering the hook into the coupler body on the other vehicle. Uncoupling involves lifting the hook, and possibly jiggling the couplers about a bit to free the hook if the pair of couplers is under tension. I quickly decided that a custom-made tool would help with this. My preferred design consists of an empty BIC ballpoint pen, with a length of piano wire soldered into the brass tip, the piano wire having the last 5mm bent at 90 degrees.


My favourite type of uncoupling tool

Meridian Couplers

K's eventually disappeared from the scene, but I still had a few K's couplers in stock. Then I discovered that Meridian Models had started selling chopper couplers. These consist of a casting containing a pair of whitemetal bodies (nicer than the K's ones, but probably even more over the scale width) and a fret of etched brass hooks.


The contents of a Meridian coupling pack

The Meridian hooks are flimsy, and to my mind slightly the wrong shape for L&B stock. So, I now make my own hooks from 1/32” brass strip (see Steps 7 and 8 of the section on scratchbuilding L&B couplers, below).

Long-term Experience and Improvements

The cast couplers have in fact all lasted better than I could have expected; one or two couplers have been damaged accidentally, and I have had one or two instances of 40 year old K's whitemetal components becoming crystalline and brittle.


Various spare couplers from my stock. From the top: a Scratch built brass coupler, a K’s white metal coupler and an unused Meridian cast coupler body

As I have built more and more sections of the L&B, and established a layout using a mixture of old and new sections (some as much as 40 years old), I have found that the single hook couplers tend to uncouple at the occasional humps in the track (e.g. at base board joints). After a lot of thought, during which I contemplated semi permanent coupling of some pairs of coaches, and/or the use of alternative types of coupler, I recently realised that most modellers accept the compromise of various exotic shapes of thin wire on the end of their rolling stock, so I tried extending the hook on some of my Meridian couplers downwards using a short length of thin phosphor bronze wire. There is an optimum angle for this wire, so that under tension it pulls the hook down into position if it should lift a little in operation, but can still be lifted manually with the couplers not in tension, to uncouple vehicles. Initial results from this modification seem very promising, although more experience is needed before deciding whether to replace all the K's couplers (which cannot easily be modified, due to their white metal hooks).


a pair of Meridian couplers, one with a scratch built hook with wire extension

Use of these modified couplings suggests the need for a modified uncoupling tool with two elements:

  • A flat blade to push the wire extension up from beneath, to raise the hook

  • A wire end to flick the hook up or down in the confined space between vehicles.

On a trip to Australia, a couple of small white LED torch key rings, with a very positive button operation to light them, were bought from a bargain shop for $2 - less than £1 each. They have had coupling tools added, so that light is available to help see that couplings are aligned. I am not yet sure that I actually like these tools I have a feeling it is useful to be able to rotate the tool in use, as can be done with a pen case, but not a flat torch body. -


LED torch / uncoupling tool

Scratchbuilding L&B Couplers

Scratchbuilt L&B couplers are quite straightforward to make. The following diagram illustrates the sequence of tasks to make a coupling:

  1. Make the coupler shaft by cutting a piece about 18mm long from a length of rectangular brass strip 3mm x 1.5mm.
     

  2. A hacksaw cut 4mm deep is made in one end of the strip, and filed smooth with a fine needle file.
     

  3. A hole for the coupling pivot is drilled about 14mm from the forked end (but may need to be less to fit on certain stock), and the width of the coupler shaft is reduced behind the fork by filing, until the brass is 1.5mm square. The sides of the fork are also filed down to an even thickness (I never manage to make the saw cut absolutely central). You then have a piece of brass like a tiny tuning fork.
     

  4. The coupler body is then held perpendicular above the end of a piece of thin 4mm wide brass or nickel silver strip, and is soldered to it.
     

  5. The brass strip is cut off, and filed to the correct size for L&B couplers (4mm x 5mm, according to the above drawing, but I have generally copied Meridian coupler plates, which are about 3.5mm x 4.5mm).
     

  6. The slot for the coupler hook is filed in one edge of the plate. Half of such coupler bodies also need a hole drilled across the body, 2mm behind the plate, for the pivot for the hook.
     

  7. Years ago, I made a template for a coupler hook from 1/16" steel plate - a slow task, with only piercing saw and tiny files! To make a new hook, I drill a hole in one corner of a length of 6mm wide 1/32" thick brass strip, and then put a dressmaker’s steel pin through the template and through the hole in the brass, and cut and file the hook to shape in a small machine vice. With care, the steel pattern does not get filed away too much each time; my original pattern has lasted well for about half the L&B’s total fleet (plus a few non-L&B models).


Making hooks: template, brass strip and steel pin, and how hooks are cut from strip

If you are making a few experimental couplers before making a template, don’t worry if they differ in shape slightly, especially along the top edge, as the originals seemed to have varied. In this case, there are two critical dimensions:

  • The distance from the hook pivot to the inner edge of the hook itself. This affects the tightness of the coupling in service – too tight and coupling/uncoupling is difficult, too slack and the vehicles in a train are too far apart.

  • The shape of the inside of the hook. If the hook is not “hooked” enough (if you see what I mean), it will ride up in motion, and uncouple at the wrong times.

   8.   The shaped hooks then have the front edges slightly chamfered, to assist them to align with adjacent couplers,
         particularly when coupling on curves. A piece of thin phosphor bronze wire is gently curved between the fingers,
         soldered to the front edge of the hook, and bent to shape to form the extension of the hook.

   9.  Finally, a hook is positioned in a drilled coupler body, and an "L" shaped piece of thin NS wire is threaded through
        body, hook and body. The wire is then bent over again and trimmed to length.

The finished couplers can be threaded through a slot in the vehicle headstock, and fixed with a small pin, such that the coupler plate is 8mm from the headstock. I have used a variety of methods of pinning the couplers, including passing the pin from above the vehicle floor and bending over underneath, on open wagons, and pinning directly into the wooden floor of my scratch built coaches.


Exe, showing the scratch built front coupling

Setting-up Chopper Couplers

It is necessary to use a simple height gauge, to check the height of couplers above rail level, and also to check that the couplers on bogie vehicles pivot from side to side a little.

The ultimate test is to run a few trains - you soon find out the particular couplers that are the wrong height, or badly-adjusted!

Conclusions

Our work as modellers is never done….

In writing this description, I have realised that my coupler bodies have followed the sketch reproduced at the beginning of this article, and the more recent Meridian design, and diverged somewhat from the actual appearance of the originals (as seen in photos), but the differences are small and easily overlooked. Also, my coupler hooks have subtly changed in shape over the years. Re-looking at some photographs suggests to me that I should try scratch building a batch of more authentic-looking units…..


     
     

 

 

  
      bring 'Lyn' back to life