Garden Railway Forum

Tidy as, and easy to use. Impressive work as always, Trevor.

More experiments and some unexpected results!

The initial couplings with 3mm diameter magnets disconnected at the slightest irregularity - so they are not powerful enough even for the skip wagons. So the same thing but using 6mm diameter magnets 3mm thick.

They are more obtrusive, of course being a light colour does not help, but they are stronger. It's an experiment and a final coupling would be black. So a long train with two types of magnetic couplings. This is climbing 1 in 60 and on a bend of course:
The couplings worked fine nothing uncoupled. So the coaches and the carriage truck were coupled using the chopper type magnetic couplings I had already tested, and the goods wagons and skips using the 6mm magnets hanging on chain links. To couple the chopper couplings to the wagon couplings I had added hanging magnets to some of the chopper couplings. Sort of emulating the wire loop I have always fitted to chopper couplings so that hook coupled wagons can hang on the end of a chopper coupled train. This is where the stray fields from magnets upset the calculations. With this type of magnet even the stray fields around their edges are strong. I knew that having different polarity at one end would be a problem, but I should have realised that even using the same polarity facing outwards would do the unexpected:
You can see how that hanging magnet is trying to attach itself to the back of the magnet in the chopper coupling. It isn't actually a problem in that if a goods wagon with a hanging magnet approaches it sometimes flips over and sometimes needs a helping push to get it to turn around and couple to the magnet on the other wagon. On the other hand the hanging magnet tucked up under the chopper coupling is out of the way of other magnetic influences - some of which will be apparent in the next post!

Trevor

That's very impressive! Could work well on a long rake of slate wagons...

So to the unexpected.

On the bottom half of the line everything worked out OK. But on the top half above the red bridge things happened - and I noticed what was happening as the back of the train crossed the first point:
You can see how the rear hanging magnet has attached itself to the rail - and that caused the couplings further up the train to part - you can see the locomotive and first carriage going gayly on their way.

Just a few inches further on it happened again. So that hanging magnet hasn't just uncoupled the train it has also derailed the last wagon:
Having sorted out the immediate issue of crossing the point ( diamond crossing actually) and setting the train off again I could see how that magnet was being drawn to the right hand rail - and was putting a twisting force on the last wagon which could easily derail it - before it is derailed by the next point.

So there is an issue with these tipper wagons and this particular version of the coupling.

So far I have only tried pulling a train. What about pushing as in shunting?

Trevor

Shunting, or at least pushing the wagons.

My initial tests in the workshop on my test track using the Wren and the tipper trucks led to the locomotive derailing as well as some of the trucks near the locomotive. The issue was partly lack of weight in the printed locomotive, and partly the couplings preventing the trucks touching each other when being pushed. Because the couplings were taking the pushing strain they were pushing the coupling pivots sideways, making the wheels try to climb the rails - hence the derailing.

So I printed magnet holders to specifically take the 6mm diameter and 1mm deep magnets. These are much more successful with these light wagons:
Here is the Wren pushing 6 tippers and two large bogie vehicles around a double curve. Nothing derailed. Here is the same train going the other way (the bogie vehicles were not attached), and everything worked fine. The couplings are 4mm shorter and that allows them to fold under the wagons when being pushed so that the drawbars touch as per the real thing.

Now I need to establish that these thin magnets are strong enough to keep these wagons together:
I also checked that the magnets don't attach themselves to stainless rail held in the middle of the track. They work in the workshop but the final test will be on the line this afternoon.

Trevor

So I can report total success!

The wren hauled the tipper wagons up the 1 in 60 from the red bridge to Tan-y-bwlch, through the points and diamond crossing, over the viaduct and into Dduallt station with no problems. She ran around the train and automatically coupled to the other end of the train. Shunting up hill on a 1 in 60 was not a problem. The return trip to the red bridge was also uneventful.

So in summary. I have a working system of chopper or Norwegian couplers for locomotives and coaches. I have a working system based on replacing the hanging hooks with hanging magnets which works for goods wagons. There are two versions of that - one for larger wagons and one for light weight wagons. I have a way of coupling the two types of couplings to each other so I can simulate the mixed working of the Ffestiniog railway (empty slate wagons on the end of a passenger train or goods wagons between loco and coaches). Locomotives approaching a train couple automatically which looks and feels appropriate..

The disadvantages are that the hanging magnets are less aesthetically pleasing than the bare hook I previously used, and that things will couple up automatically when you don't want them to (like when you pick a coach up to put it away).

I will add the files for making the hanging magnet holders to the 3 D printing section. However be aware that these print perfectly in a resin printer - and I have not tried them on a filament printer.

I will check the chopper coupling files for errors and then add them to the same place.

I think that really completes this thread unless anyone else wants to add anything!

Trevor

Glad you finally got them sorted out, Trevor. Sounds like you've cracked it!

Rik