LMR: Hornby era 1 carriages

[What About The Bee]

The Hornby LMR carriages used the carriages in the museum as the prototype. I think that a fine choice, as the enthusiast can say they match the "real thing". Of course, the real thing matched 1930s LMS engineering, not 1830s LMR!

Placing the 1830s imagery side by side with 1930s/Hornby imagery reveals a startling difference. I wonder if you can spot it

Glass Carriages 

Blue Boxes

There are plenty of tiny differences, but those are not my focus  The one that always catches my eye is the difference in wheelbase. The axles are so much closer together in the 1830s.  

The solution is not that the 1830s imagery is fantasy. The Ackermann prints are excellent. They depicted what the artist observed.

The answer is found in LMR turntables. Those turntables were sprinkled all over the LMR. At the Liverpool Road Station in Manchester, the track plan¹ shows 55 (fifty five) turntables at that station!! Just that station.

Armengaud presents us with a detailed mechanical drawing on one such turntable.  

The plan view is most illustrative

There is a scale directly by that plan view, and I have added yellow lines to show 2 meters leading into the turntable. From this, we can observe that the tracks on the turntable were 2 meters long +/-.

In that same drawing package, Armengaud provided us with a mechanical drawing of a planet-class locomotive. Armengaud carefully denotes the wheelbase of that locomotive. 1.5 meters.

Essentially, when the chords of the flanges of a planet class wheel are included, that locomotive fits on the turntable with just inches to spare.

Even though the carriages did not need to be turned round to 'face in the right direction', the requirement to switch tracks was ever present. The wheelbase on the carriages was simply as large as it could be, and still fit on a turntable.

Yes, the wheelbase really was that small, something the 1930s LMS engineers missed.

Bee 

¹Fitzgerald, 1980, "Liverpool Road Station, Manchester. An historical and architectural survey" 

[LTSR_NSE]

@bee - is the suggestion that original wheelbase was ‘missed’ fair? has an LMS source ever suggested that their 1930s carriages were intended to be faithful recreations?

The very little I have read suggests that ‘aesthetically pleasing approximates’ were created using current (1930s) wagon wheels, axles and chassis components (& 1930s technical/design knowledge).

Therefore the differences could be attributed to stability/safety improvement, rather than careless/incomplete research.

Your research into the 1830s designs & engineering is fascinating as always!

[What About The Bee]

Hello LT&SR_NSE

Perhaps my word "missed" was a bit harsh.

In all my research and reading, I do try to give the most credence to contemporary resources and first person testimony.

Interpretations at a later date by anyone always suffers from the imperfect knowledge of the record. I suffer from this today, as did the LMS then. This can lead to erroneous conclusions, especially by me.

I was always bothered by the 1830s depicted wheelbase. It does seem unstable. Yet the axles are right at the cabin separators. The only load that is truly cantilevered are the three passengers all the way on the front bench in the first cabin OR in the last bench in the third cabin. The remaining 4 benches are so close to the axles or in between the axles so as to be inconsequential for analysis.

WARNING, an arithmetic exercise follows. Period estimates suggested that 12 passengers weighted 1 ton, or 167lbs each. Thus 3 passengers weigh 500 lbs. Pambour, a period author, notes that a fully loaded first class carriage weighed 3.65 tons and second class 2.23 tons, so 7300 lbs and 4460 lbs respectively. Assume 18 passengers, and the unloaded carriages are 4300 lbs and 1460 lbs respectively. Thus 500 pounds will upset the balance, but not result in a carriage tipping over. Perhaps 3 very chubby passengers; with no other passengers in the carriage; seated in the first row; bouncing up and down simultaneously could be an issue. That goes right out the window once we add other passengers in other compartments. Its not an issue in my estimation.

The LMS moved the axles out to the front edge of the seats. Roughly 4 feet total or 2 feet for each axle. (See image). While we could argue that this is technically more stable, and it is, it is not a significant change in my view.

The engineers at the LMS were asked to make a reproduction, based on....cartoons? Did they have online access to obscure tomes and artwork. No, they did not. I think they did a great job and in general, the appearance is similar. No doubt, they thought the approach they took was safer, more conservative and effective. Hats off to those lads. The carriages do look the part.

When I was first confronted by the wheelbase, I thought to myself, that cannot be. I have pages and pages of calculations, based on the artwork by known good observers. I could not achieve a solid result, just some inconclusive guesses. I was bothered enough to find mechanical drawings of turntables and to compare that to the wheelbase. Something that may not have troubled the engineer tasked with the wheelbase issue at the LMS. I've been at this for years and years. I do not think the lad at the LMS had the same luxury of time.

The result of that comparison provided me with a very good answer, one I think we can rely upon. The 1830s turntables were tiny. The LMR had a large quantity of them installed. The carriages were made to match.

Ordinarily, I would not bother the forum with such trivia. But the recent interest by 81F in the blue boxes encouraged me to share a bit more than previously.

Lest there is any confusion, I am thrilled with the Hornby representation of Era 1, LMR kit. Simply over the moon with it.

If I had not raised the issue as a matter of interest, it would hardly be noticed by the vast body of enthusiasts. I like to share these details as a way to bring out the richness of the era, certainly not to denigrate anyone.

My apologies for the choice of the word. Mea culpa.

Bee

[Peter Stiles]

I'm looking forward to seeing the first modified Hornby carriage showing the historic wheelbase.. not sure I'm brave enough to take my razor-saw to these coaches.

[Rana Temporia]

If someone did knock up a test chassis with the shorter wheelbase I would be interested in the stability of it and also how it affected the couplings on tighter curves.

[atom3624]

May need some form of kinematic coupling to be set up?

[What About The Bee]

When created, these carriages were considered 2nd class, not 3rd. They only became 3rd class in the 1840's, when the LMR finally created enclosed 2nd class. The LMR demoted these, a function of Parliament regulation and also competing railways, who did not offer open travel.

Image Analysis of Stephenson's Open Carriage.

The image presented in this analysis may be ironically be found here: Hornby on Stephenson's Open Carriage

Human anatomy has not changed since the 1830s. Some may suggest we are taller or wider, but the analysis presented here is based on the length of a seat. If you search the internet for seat dimensions, you will find that the bench part of a seat is roughly 17".

If you take 17" as a ruler, and mark pixels, you may determine inches per pixel. From that, we can measure pixels and determine other lengths in inches!

The annotated image shows the seat at 17". Therefore the wheels are 3'2" and the wheelbase 70.5". Please do take these dimensions with a grain of salt.

Recall, however, Armengaud's drawing of a turntable (above), you will see 2 meters, or 78.74". The Stephenson open carriage annotated here does fit on that turntable, but with only inches to spare. As you would expect!

The Model

So what of the model? I measure the wheelbase to be 34mm or 1.34". Likely this matches the scaled LMS reproductions.

Yet 70.5" in OO should be 0.92" (~15/16"). That is a fairly large delta at this scale.

I had a very, very close look at the model, to see the method of axle support. The entire side frame includes the spring, horn guides and horn block, for both axles, molded as one piece. Whilst you could saw it off, re-attaching it while simultaneously keeping the axles parallel to each other and to the floor of the carriage will prove incredibly challenging.

This and other historically accurate carriages are on my list. Some mechanical drawings do exist. Printing the chassis, whilst keeping the carriage body will be my approach.

Bee

[Rana Temporia]

Bee, I noticed someone had 3D print files of a similar coach on the internet and I think it was a free download. As you are 3D CAD proficient it should be easy to move the axle boxes on the model to match the shorter wheelbase. I think the item was on Thingiverse. I can’t access my computer at the moment and for some reason I can’t copy links on my iPad but if I can find it later I will add the link. Col

[Rana Temporia]

Bee, it is on Thingiverse and the item is ‘Victorian Rocket Open Carriage Wagon OO’.

[What About The Bee]

Thank you Rana (Col?)

I did find the item and had a very close look at the imagery.

While it has the look and feel of the carriage, details show it to be a fairly coarse model. The print is targeted for FDM. Four sides are printed independently and whacked onto an un-detailed chassis, which mirrors the LMS wheelbase.

I would essentially have to rework the entire assembly. I do appreciate the effort you put into this and thank you for that

Bee