Dundas Tipper Wagon

[Stefan Krebs]

Dear Stephen,

If you use a bent wire aka ROCO (better than Eggerbahn as it is wider) and let the frame act as 'buffer' (as the prototype does) you're reasonably close to the nearest axle with your buffer face, and unless you have extremely tight radii this should work just fine, the width of the hoop will allow for enough side-play to avoid derailment.
If you add a coupler, e.g. Greenwich, you're pushing the buffer face away from the nearest axle, i.e. create more 'overhang', which means the coupling will swing away from the centre of the track, - the more overhang the worse. That's not a problem if the overhang is about the same on all your rolling stock, but it will cause derailment if the overhang varies. Practically all commercial rolling stock, including the prototype, have swivelling couplers for that reason alone!
Without swivelling point a fixed coupler can push or drag its vehicle or the connected one sideways of the track causing derailment as on larger overhang (>~7mm; depends on radius as well) there is not enough leeway in the width of the hoop to compensate for the side-ways movement caused by the overhang.

Being a very small vehicle you will struggle to manually centre a swivelling coupler, i.e. if swivelling coupler, than you need the centring spring too, otherwise you have to fiddle around every time you want to couple up.

To see this in action get yourself A ROCO or Eggerbahn industrial truck (anyone with oblong frame) and a ROCO mine tub (inside frame), which has a substantial overhang. If you put those on a curved (flexi-)track you will see that if the radius is tight enough one is forced off the track.  :laugh:


Hope this helps
Waldschrat

[Stephen Rainsbury]

Thanks Gents, I can see both sides there so I think I am going to try it just to see what happens and understand it better for future models :-)

[JulienW]

The key, I believe, in fitting couplings to the Dundas tippers, and any other short wheelbase wagon come to that, is to do so in such a way as to minimise the amount the business end of the coupling (the buffer and peg) overhangs the end of the wagon - that's partly why the Dundas kits (and other kit skips from Nigel Lawton and Saltford Models) have the peg molded onto the  chassis and ready to run skips of a similar size (Peco, the european makers) have the coupling integrated into the chassis molding.

The photos of Alec Hudson's conversion - using the Peco couplings in his example - is the sort of thing to aim for, and has probably been the most useful addition to this discussion. Fitting the Greenwich couplings that you would like to use may be easier, as being etched it should be possible to lay them on top of the central spine (once the upper surface detail is removed to give a flat surface) with the 'lugs' for the loop pivots bent downwards either side of the spine and the back face of the buffer hard up against the outside of the curved chassis end.

I haven't been able to find my skips with the DG couplings yet but the principle is much the same as shown in Alec's photos, and with the minimum amount of coupling overhang there is no need for any of the complications of fitting pivots and centering springs, even for use on tight  (around 6") radius curves that might be prototypical in an industrial setting where any coupling overhang is most likely to cause issues.

Best of luck with your experimentation.
Julien

[Stephen Rainsbury]

... (Peco, the european makers) have the coupling integrated into the chassis molding.

... Fitting the Greenwich couplings that you would like to use may be easier, as being etched it should be possible to lay them on top of the central spine (once the upper surface detail is removed to give a flat surface) with the 'lugs' for the loop pivots bent downwards either side of the spine and the back face of the buffer hard up against the outside of the curved chassis end.

Thanks, I have been experimenting with several trucks and am starting to get a better feel for the issue. I haven't hacked the truck yet (getting over cold and feel rough) but I think I am going to chop down the ends of the truck so the tab on the Greenwich coupling will be in exactly the same place as the original one on the truck, and see how it goes from there.

I still haven't actually made one up yet, I feel so knackered that I just know I will mess it up :-)

[JulienW]

I can sympathise about the cold, as I seem to get 'knocks me out for 3 weeks' colds rather than a minor sniffle with the odd cough and sneeze that lasts a week.

It's probably worth leaving it for now until you can breath properly (and I always find trying to think with a head full of goop difficult) and tackling the job when you feel up to it.

Get well soon!

[Alan Feldon]

Two suggestions either of which require you to drill a hole through the central part of the chassis
1) Purchase a packet of the original Peco couplings-the ones that require you to cement the two halves together .Use the wire loop from these and slot in the hole you have drilled in the chassis member.The plastic part of the coupling can be used on locos
2)Use the loop from Greenwich couplings or super glue an assembled coupling either under or above main central part (whichever height lines up with your other couplings )

[Stephen Rainsbury]

Two suggestions either of which require you to drill a hole through the central part of the chassis
No problem chopping bits out of the frame, its freelance anyway :)

2)Use the loop from Greenwich couplings or super glue an assembled coupling either under or above main central part (whichever height lines up with your other couplings )
I was starting to think that way too, but somebody from FB sent me an article they had written about making Greenwich couplings fit.  I am going to need a new Swiss saw to make incisions so that I can bend the tabs a bit closer than default, although I think now that I might have worked out how to use the Greenwich loops, as you suggested, but keep the original Dundas peg.

Thanks Alan.