Couplings - How did they make them?

I've been busy making bits for the front coupling on my LSWR O2 0-4-4T to Don Young's Fishbourne design in 5"G. I can think of a number of ways to assemble the top link to the coupling hook, involving silver-soldering bits together, but looking at photos of the real thing, how on earth did they do it when they made them? Did they forge the link ends after they'd passed it through the hole in the hook? No way would the finished link pass through the hole! Some links on Other Railways have a flat on them to pass through a slot provided above the hook hole, but not on these. A slot in this hook would weaken it too much.

This is Calbourne in full size:

I suppose they enjoyed making life difficult for themselves back in the day...

Clever bit of blacksmith forging, putting the second eye on after passing through the hole in the hook?

+1 on a forge weld on one side of the link between eye and hook bend, lots of room there to make a scarfed forge weld very strong. Parts may have started out one being long rod and one eye, passed through hook and bent, then a short rod and eye welded to it. Also possible to pass through a long rod rod and eye, wrap-bend form the second eye, forge weld the second eye, then bend at the hook and adjust centre distances of eye to be even. Skilled work in any case.

+1 on a forge weld on one side of the link between eye and hook bend, lots of room there to make a scarfed forge weld very strong. Parts may have started out one being long rod and one eye, passed through hook and bent, then a short rod and eye welded to it. Also possible to pass through a long rod rod and eye, wrap-bend form the second eye, forge weld the second eye, then bend at the hook and adjust centre distances of eye to be even. Skilled work in any case.

You’d need to examine it closely for tool marks but if these were made by the hundred then my guess is both ends were likely drop forged in several stages. The link is certainly long enough for the hook to be placed out of the way whilst the ends are formed.

You can see some couplings where there is a slot in the top of the hook hole and a flat at one part of the link so it can drop though the slot yet be retained being too wide when in normal position. Productionised to reduce need for skilled workers.

Hadn't ocurred to me before, but it is possible the link could be forged first, set in a sand mould, and the hook sand cast around it. This is a technique that used to be used for large cast chains for ships. Two links were cast then placed in a sand mould where the third link was cast around the end loops of the original two links.

I have no idea whether this was ever done for these links, or if hooks were ever cast -they may have only been drop forged, for additional strength vs castings. Maybe someone who used to be at a loco works can tell us.

I can't answer your question as such but I do know that it's now usual for the drawbar to have a slot cut out of the top and corresponding flats on part of the shackle to enable it to be removed.

Its just about visible here :-

http://www.google.co.uk/search?q=railway+couplings&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjPisug8s7bAhUIbRQKHYN2B1UQ_AUICigB&biw=1438&bih=626#imgrc=nDiKk_mlw1MtXM:&spf=1528832870776

Edited By Gas_mantle. on 12/06/2018 20:49:30

As a retired blacksmith, these would have been made from a single piece of tool steel. Upset one end and form the eye, then hot punch the hole and drift to size. Push through the hole in the hook and repeat the process. It would never have been welded.

Since chains are usually used in tension, a cast link (cast iron?) would be a no no. Cast steel might be different.

Anyone like to comment on the strength of cast steel in tension, versus rolled steel bar?

Howard

Mobile crane hooks are always forged from high carbon steel, so it would be safe to assume that train hooks would be made in the same way. Depending on the length of the train the load on the hook could be upto a 1000 tons.

Waggons don't normally hang vertically from the locomotive.

Chains on waggons were made by bending 2 U shapes and resistance welding them together in the 1950s, and the first waggon had to take the full load. I have a very good ILocoE paper about waggon building. In the early 50's BR had over 1,000,000 waggons, quite a thought. Making new ones was big business as they didn't last for ever

The load is the same on the hook wether you are pulling the load or lifting the load.

Posted by Mark Rand on 12/06/2018 23:57:23:

Oh no it isn't, There are not many locos with a tractive effort of 1000 tons, but plenty of trains that heavy. Tractive effort of a 9f was about 17 tons. You'd probably want a higher capacity in the chain to allow for snatch loading.

Hi Nigel,

I did not know you were building a 5"g O2 to Don Young's design. I have made the SR type coupling so if you want any details happy to assist, plus I have the original drawings for the Drummond chimney that show that Don got this detail quite wrong.

Cheers,

Julian

If you fit a strain gauge and get a reading of 1000 tons, the load is a 1000 tons irrespective of orientation. Coal trains of 15,000 tons of coal are common in South Africa.

The load on a hook lifting is considerably more than it is when hauling.

On level ground an averagely built adult male can push a 12ton railway wagon from a standing start and once going can get a decent speed with little effort, I don't know of anyone who can lift that vertically.

Take a spring balance and take a reading pulling something on the level, keep increasing the gradient and the load increases until you reach the maximum when at a vertical lift

Edited By Gas_mantle. on 13/06/2018 00:51:45

Just look at a practical scenario - that of one man moving a large plane on a flat runway. Simple, when one thinks about it.

There is no weight on any flat track in the direction of the applied force of the engine. Gravity works perpendicular, so towards the centre of mass of the Earth. It is only the friction between the track and wheels that provide anything more than the inertia of the load to get it rolling and to accelerate.

The load will accelerate according to Newton’s Second Law of Motion, once the static and rolling resistances are overcome.

As Duncan says, a snatch force will be greater that the simple tractive effort fom the loco. Laws of momentum come into play on this scenario.

Look up f = m*a and m1*v1 + m2*v2 = m3*v3 in respect of the two laws.

Remember the track with one end elevated to provide constant velocity, when doing experiments to demonstrate Newton’s Second Law at school? Or perhaps recall experiments with a linear air track? I do.

Pushing a 12 ton wagon and lifting a 12 ton wagon are not equal loads. I cannot see anybody having a pushing force of 12 tons. A strain gauge reading with of 1000 tons on a train will be pulling much more than a 1000 tons. Strain gauges measure the applied load not the physical weight.