Southwold coach
Re: Southwold coach
Managed to test over the entire railway this weekend. There are still two places where it sometimes derails but I can see why it's happening. Oh for a billiard-table railway!!
Rik
Rik
- Peter Butler
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- Location: West Wales
Re: Southwold coach
Congratulations Rik, it not only looks good but performs well too. I know nothing about the prototype in action but should the centre truck extend so far outside the width of the coach sides?
The best things in life are free.... so why am I doing this?
Re: Southwold coach
No. But I don't think the curves on the Southwold were as severe as on the PLR.Peter Butler wrote: ↑Sun Dec 06, 2020 9:44 pm Congratulations Rik, it not only looks good but performs well too. I know nothing about the prototype in action but should the centre truck extend so far outside the width of the coach sides?
Rik
Re: Southwold coach
Very nice Rik! A rake of those is going to look The Business...
Incidentally, for those interested in such things, here's how Hornby solved the "six wheels and tight corners" issue back in the 80s:
It's quite ingenious, the centre truck floats freely within the guides (there's quite a lot of vertical play) and is attached to the couplings, which are themselves pivoted so that they also follow the curve.
It's not high on my priority list, but you never know, I might try to build a Cleminson vehicle one day - the NWNGR had some Cleminson carriages and a wagon, and the FR still has a coal wagon built on that principle, the story of which makes interesting reading. It seems they still have trouble getting it to run properly! ee: https://www.festipedia.org.uk/wiki/Clem ... led_waggon
Cheers,
Andrew.
Incidentally, for those interested in such things, here's how Hornby solved the "six wheels and tight corners" issue back in the 80s:
It's quite ingenious, the centre truck floats freely within the guides (there's quite a lot of vertical play) and is attached to the couplings, which are themselves pivoted so that they also follow the curve.
It's not high on my priority list, but you never know, I might try to build a Cleminson vehicle one day - the NWNGR had some Cleminson carriages and a wagon, and the FR still has a coal wagon built on that principle, the story of which makes interesting reading. It seems they still have trouble getting it to run properly! ee: https://www.festipedia.org.uk/wiki/Clem ... led_waggon
Cheers,
Andrew.
Re: Southwold coach
The model certainly looks like a Southwold passenger coach, so you've nailed that part of the project. I'm also impressed you managed to get it to work on R1 curves.
I can't find any mention of the Southwold minimum curve radius, but the book 'Branchline to Southwold' has a reprint of a piece printed in 'The Engineer' in 1878 describing Mr. Cleminson's brainchild. It mentions that North Wales Narrow Gauge Railway trains with these coaches were running on two chain curves and had safely reached the heady speed of 20 mph.......
What part of your track has problems with the model? Reverse curves by any chance, or are the problems on track with vertical curves?
I've always been intrigued that the diagrams of how Cleminson underframes work only ever show them on constant radius curves. Reverse curves are never discussed, nor what happens when passing from straight to curved track.
A thought experiment suggests that when running through a reverse curve the end axles will be trying to rotate in opposite directions and the whole shebang will become a very long rigid 6 wheel underframe as it passes through the transition from one curve to the other.
The Southwold Cleminson wagons have a much shorter wheelbase, so should be easier to get to work on your track I would think.
Regards,
Graeme
Re: Southwold coach
Peter Paye's book says the sharpest curve on the Southwold was at Halesworth with a radius of 5 chains. Not sure how the NWNGR coaches compared in length with the SR coaches. I had to bring the outer wheels inboard and increase the width of the centre truck to allow it to negotiate my curves.GTB wrote: ↑Mon Dec 07, 2020 1:51 pm I can't find any mention of the Southwold minimum curve radius, but the book 'Branchline to Southwold' has a reprint of a piece printed in 'The Engineer' in 1878 describing Mr. Cleminson's brainchild. It mentions that North Wales Narrow Gauge Railway trains with these coaches were running on two chain curves and had safely reached the heady speed of 20 mph.......
The problems I'm encountering are with vertical curves - more particularly dips where the centre wheels lose contact with the track.GTB wrote: ↑Mon Dec 07, 2020 1:51 pm What part of your track has problems with the model? Reverse curves by any chance, or are the problems on track with vertical curves?
I've always been intrigued that the diagrams of how Cleminson underframes work only ever show them on constant radius curves. Reverse curves are never discussed, nor what happens when passing from straight to curved track.
A thought experiment suggests that when running through a reverse curve the end axles will be trying to rotate in opposite directions and the whole shebang will become a very long rigid 6 wheel underframe as it passes through the transition from one curve to the other.
I've tried it through the R2 reverse curves at Beeston Market and it gets through OK, though I can feel resistance from the flanges just before and after the half way point. The coach wheelbase seems just right for R2 reverse curves as one outer wheelset is leaving at the other is entering the curve.
Peter Paye observes (p209)
Maybe I should buy a lathe ......The coaches advanced in a diagonal movement when in motion and tyre wear was above average especially on the outer pairs of wheels. The wheelsets were regularly sent ...... for retyring and deep tyre turning .....
I did wonder whether to construct a wagon first, but figured that if I could sort out the undercarriage for the coach then modifying it for the wagon would be easier than vice versa.
Rik
Re: Southwold coach
That's interesting, as an R2 curve is approx. 2'6” radius, which scales out to 50' on a real 3' gauge railway. The minimum design radius for a quarry Hunslet was 50' and I bet the flanges were squealing on that tight a curve. Somehow I doubt a Cleminson underframe would have got around the track in Penrhyn quarry.......ge_rik wrote: ↑Mon Dec 07, 2020 3:02 pm The problems I'm encountering are with vertical curves - more particularly dips where the centre wheels lose contact with the track.
I've tried it through the R2 reverse curves at Beeston Market and it gets through OK, though I can feel resistance from the flanges just before and after the half way point. The coach wheelbase seems just right for R2 reverse curves as one outer wheelset is leaving at the other is entering the curve.
If it's just dips in the track that are left as the main issue and if you aren't already using them, fitting LGB wheels with their deep flange in the centre truck would help, but calling out the track gang when the weather improves for a bit of track lifting and ballast packing would be a better way forward long term.
Last resort would be to build in more vertical play in the steering linkages and lightly springing the centre axle with coil springs which would give the longest spring travel.
That's a very interesting comment by Paye. One of the major claims by Cleminson was that his system would reduce tyre wear.ge_rik wrote: ↑Mon Dec 07, 2020 3:02 pm Peter Paye observes (p209)
Maybe I should buy a lathe ......The coaches advanced in a diagonal movement when in motion and tyre wear was above average especially on the outer pairs of wheels. The wheelsets were regularly sent ...... for retyring and deep tyre turning .....
I have actually seen serious flange wear on brass wheels in HO scale after many, many hours of running. With steel wheels and brass track, I would expect to see rail wear first on my garden railway. Given how little running I do, I haven't even seen the tarnish worn off the rail so far.
A lathe is a useful thing in modelling, but one big enough to turn wheelsets costs about the same as buying 120 steel commercial wheelsets.......... That said, if you can figure out how to use a 3D printer and find a use for it, you can probably do the same with a lathe.
Either way would work I think. The main requirement is to be stubborn enough to fight a recalcitrant project into submission.
'Nil Desperandum Carborundum'
Graeme
Re: Southwold coach
Hi All.
This is my home built NWNG railway Cleminson carriage. My difficulty was also trying to keep the centre truck on the track. I initially made it with a flexible coupling of rigid arms connecting the centre truck to the end trucks similar to the system below as used by DLT. On RM Web(His photo). This however did not allow enough flexibility for the lines I run it on. The problem was, as said, on reverse curves where a parallel siding left the main line for instance. When the first truck was turning onto the curve of the turnout the middle and rear truck were still on the strait track, but because of the front truck turning it was forcing the middle truck sideways which made it leave the rails. I then had to redesign my model with a more flexible system as shown below. I used a length of thin plastic coated steel wire to connect the centre truck to each end truck. It is screwed to the centre truck and passes through a hoop about half way along the end truck arm giving about 4cm of unsupported wire either side of the centre truck. This allows one end truck to turn while, due to the flexibility of the wire, the centre truck can still be on strait track. In the extreme case, while one end truck is on the siding and the other end truck is on the parallel main line, the centre truck can be going round the curve of the turnout.
I also allowed plenty of vertical movement in the centre truck guides to allow for the length of the carriage on uneven track.
David.
This is my home built NWNG railway Cleminson carriage. My difficulty was also trying to keep the centre truck on the track. I initially made it with a flexible coupling of rigid arms connecting the centre truck to the end trucks similar to the system below as used by DLT. On RM Web(His photo). This however did not allow enough flexibility for the lines I run it on. The problem was, as said, on reverse curves where a parallel siding left the main line for instance. When the first truck was turning onto the curve of the turnout the middle and rear truck were still on the strait track, but because of the front truck turning it was forcing the middle truck sideways which made it leave the rails. I then had to redesign my model with a more flexible system as shown below. I used a length of thin plastic coated steel wire to connect the centre truck to each end truck. It is screwed to the centre truck and passes through a hoop about half way along the end truck arm giving about 4cm of unsupported wire either side of the centre truck. This allows one end truck to turn while, due to the flexibility of the wire, the centre truck can still be on strait track. In the extreme case, while one end truck is on the siding and the other end truck is on the parallel main line, the centre truck can be going round the curve of the turnout.
I also allowed plenty of vertical movement in the centre truck guides to allow for the length of the carriage on uneven track.
David.
Last edited by River Lin on Fri Dec 11, 2020 11:53 am, edited 1 time in total.
David T.
Re: Southwold coach
That looks ingenious, David.
I'm still fiddling with my system. I've now given the centre truck a lot more downward movement to cope with the deepest dip on my trackwork which also happens to coincide with a curve and a point. I'm finding the outside wheel now sometimes lifts up off the track. I've piled more lead on to the truck but that's not cured it. The next job is to get the PW gang to sort out the track!
All good fun. I'm going to stick with it!
I've just examined the track layouts of all the Southwold stations and it looks like the coaches were never faced with reverse curves, even on the sidings where they stored the coaches. Not sure if it was deliberate planning or serendipity.....
Rik
I'm still fiddling with my system. I've now given the centre truck a lot more downward movement to cope with the deepest dip on my trackwork which also happens to coincide with a curve and a point. I'm finding the outside wheel now sometimes lifts up off the track. I've piled more lead on to the truck but that's not cured it. The next job is to get the PW gang to sort out the track!
All good fun. I'm going to stick with it!
I've just examined the track layouts of all the Southwold stations and it looks like the coaches were never faced with reverse curves, even on the sidings where they stored the coaches. Not sure if it was deliberate planning or serendipity.....
Rik
Re: Southwold coach
I've seen two wheel trucks on steam locos do that on curves, usually the lead truck.ge_rik wrote: ↑Wed Dec 09, 2020 4:08 pm I'm still fiddling with my system. I've now given the centre truck a lot more downward movement to cope with the deepest dip on my trackwork which also happens to coincide with a curve and a point. I'm finding the outside wheel now sometimes lifts up off the track. I've piled more lead on to the truck but that's not cured it.
In the cases I've seen the truck side control forces were applied above the axle, which meant that when the flange was against the rail the side control force tilted the truck using the flange as the pivot and the other wheel lifted off the rail.
If the side force is applied below the axle, the wheel that was lifting is pushed down harder instead........ The fix we made was to move the side control springs down so they were acting below the axle centre line and I now always do that with two wheel trucks on locos. I build.
Since the control arms in every cleminson model I've seen are tucked up out of sight behind the side sills, it may be that the centre axle is running out of travel and is being tilted by the steering forces from the other axles. The lever ratios are presumably high enough that they were able to lift the added weight as well.
If this is what's going on, lifting the track won't stop the axle tilting when the centre truck runs out of travel. Something like David's flexible wire connections, fitted so that they act below the axle on the centre truck might do the trick though.
Graeme
Re: Southwold coach
Thanks Graeme. Another really comprehensive answer.GTB wrote: ↑Thu Dec 10, 2020 10:39 am
I've seen two wheel trucks on steam locos do that on curves, usually the lead truck.
In the cases I've seen the truck side control forces were applied above the axle, which meant that when the flange was against the rail the side control force tilted the truck using the flange as the pivot and the other wheel lifted off the rail.
If the side force is applied below the axle, the wheel that was lifting is pushed down harder instead........ The fix we made was to move the side control springs down so they were acting below the axle centre line and I now always do that with two wheel trucks on locos. I build.
Since the control arms in every cleminson model I've seen are tucked up out of sight behind the side sills, it may be that the centre axle is running out of travel and is being tilted by the steering forces from the other axles. The lever ratios are presumably high enough that they were able to lift the added weight as well.
If this is what's going on, lifting the track won't stop the axle tilting when the centre truck runs out of travel. Something like David's flexible wire connections, fitted so that they act below the axle on the centre truck might do the trick though.
Graeme
I did wonder about using some sort of springing system. It's interesting that the outer wheel only lifts when the coach is travelling in one direct but not when it travels in the opposite direction. I've tried turning the coach around in case it was something to do with the leading outside wheel truck, but the lifting was unchanged, Ok going forwards, wheel lifting in reverse. It's odd. As you surmised though, if I give one of the outside trucks a poke the middle wheel drops back on to the track.
I'll keep tweaking .... I won't be defeated. ..... (Yet!)
Rik
Re: Southwold coach
That's the spirit.........
I used to get similar behavior with HO models, especially the older scratchbuilt ones......
There could be some asymmetry in the track curve at the problem place. The couplings may be involved for that matter, as the forces steering the outer trucks will act differently between pushing and pulling.
Graeme
Re: Southwold coach
It's been a while since I revisited this project. If you recall, I designed and 3D printed a Southwold 6-wheel coach and took a while to tinker with the underframe until it worked reasonably reliably. However, there were a couple of places on my railway where the coach sometimes derailed. At Bulkeley station it was because there was a dip in the track which meant the centre truck floated above the rails and at Beeston Castle it was the opposite - there was a hump which meant the coach see-sawed on the centre truck and one of the outer sets of wheels left the track.
Rather than yet another redesign of the coach underframe, I ripped up the track at these two stations and have just finished relaying it to eliminate the offending undulations. It was worth it, because I also ironed out a few kinks in the track at the same time and, as I also had to remove and replace the island platforms, I installed some wiring for gas lamps beneath them.
Rik
Rather than yet another redesign of the coach underframe, I ripped up the track at these two stations and have just finished relaying it to eliminate the offending undulations. It was worth it, because I also ironed out a few kinks in the track at the same time and, as I also had to remove and replace the island platforms, I installed some wiring for gas lamps beneath them.
Rik
Re: Southwold coach
That seems like time well spent Rik. Looking forward to the finished installation.
As an aside, the castle has weathered in really nicely now.
As an aside, the castle has weathered in really nicely now.
Philip
Re: Southwold coach
Thanks
Yes, it's mellowing nicely. In a couple of years' time I may have to attack it again with the cement dyes
Rik
Re: Southwold coach
Well, it's taken a while but my second Southwold Cleminson coach has just entered service. This seems to have taken longer than the first to construct, maybe because I've been tweaking its design in the light of experience with the first. I think I've got the 6-wheel chassis sorted out but I've not yet had a chance to run both coaches together in a full session - fingers crossed!
Coach number three is about to be printed. It'll take a while as there are quite a few large bits to be done....
Rik
Coach number three is about to be printed. It'll take a while as there are quite a few large bits to be done....
Rik
Re: Southwold coach
Thanks Andrew.
I've tried to recreate this iconic image of the Southwold Rik
I've tried to recreate this iconic image of the Southwold Rik
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