Looking at a lot of photos it seems that there is a very wide variety of buffers and couplings fitted to metre gauge stock. Knuckle couplers, chopper types, single buffers with one or two chain couplings, all the way through to fully automatic stuff on modern stock. I researched both knuckle and chopper style couplings which would be about the right size for 1/50 scale. A  few might be suitable, but would be difficult to achieve what I’m looking for.

 

Since this is a freelance project I can choose from quite a range. But perhaps it is better to come at it from the modelling perspective.

 

What do I want from a model coupling for this project?

 

1. It needs to be reliable with the ability to couple, uncouple or stay coupled on curves that may be tighter that those on real railways.

2. It can be unidirectional, I don’t envisage turning stock round.

3. It needs uncouple at specific points on a layout when required to, but only when required to.

4. If manual uncoupling is ever needed it should be simple.

4. The buffer part should be sprung and actually buff.

5. It should be readily available, or manufacturable from material which is likely to be available using simple jigs

6. It should be cheap.

 

What caught my eye was the larger curved style central buffers fitted to some metre gauge locos and freight stock. Could this be used as both a buffer and a coupling?

 

Time to make some. Here is the third attempt , I quickly found out that a jig to ensure it all lined up was needed. The plates are are 6.4 x 0.33 mm brass strip, the front one doubled up. I use smiths couplings with the hook slimmed down in 4mm but I just glue them in, so I have plenty of spare springs. Shafts are 2mm steel, the bushes are turned brass so the the whole thing sits square with no droop.

 

 

 

Next, a coupling. Brass tube 1mm od with a spring steel hook. Using tube as a pivot means it moves easily. There is a 3mm dia magnet, N facing down in the tube which acts as a counterweight.

 

 

 

Fitted to the bottom of a test wagon chassis. Crude but fine for a test.

 

 

A pair of wagons coupled up.  A magnet with N up under the board opposes the one on the coupling which just pivots down. Similarly if the magnet is waved above the wagon N down it uncouples. Although the axle is 3mm steel it doesn’t move the wagon unless you get too close.

 

 

 

 

 

So on to the loco. Heavy brass buffer beam bolted to the mainframe so it can be removed for maintenance. The coupling , in the same style as the wagon ones is on a bit bigger brass pivot , 1 mm id tube. The steel pivot pin can be slid out to drop the coupling, and there is a turned brass counterwieght. To the side of the counterweight is a brass tube, 1mm od with a bit of spring steel wire sticking out of it aimed at just below the weight centreline.

 

 

 

At the other end is a similar arrangement. The T bar is held high by the counterweight, the spring steel pushes it down dropping the adjacent coupling under the buffer.

 

 

 

 

In the middle is a servo. The ch 3 output from the rc reciever is a toggle and conveniently moves the servo through about 90 degrees.

 

 

 

 

So, working buffers and couplings, together with a loco that can uncouple anywhere at the press of a button.

A bit of rough video of me playing with it all. In the first part I’m just waving the magnet under the board.

 

 

 

Yep, I think that meets all my requirements.

 

I’m sure all of this has been done before, either with radio or dcc control. I see that dcc driven motors for uncoupling kadees are available. But do they meet requirement No. 6 ? That lot cost me a few bits of brass and a 2 quid servo.