Planet Update

[What About The Bee]

In translating Armengaud's fabulous 2 dimensional drawings into a 3 dimensional CAD model, I firmly decided on two changes.

The first is that the Armengaud drawings are of a Planet-class locomotive, intended for France. Not Planet, a Planet-class locomotive. It is a Left Hand Drive locomotive. That is, the engine men drive it from the left hand side of the plate, as they faced forward. This, I cannot abide. Planet, LMR#9, was a Right Hand Drive. It is relatively straight forward to flip the Armengaud image over, making it a mirror image. The back head and controls will be a mirror image of Armengaud.

The second major deviation is that Armengaud shows the forward suspension (spring assembly) under the frame. Yet Robert Stephenson and Co show the front suspension over the frame [red arrow].

The existing Planet reproduction also has the front suspension over the frame. So over the frame it shall be, in contravention to Armengaud. I did follow Armengaud, simply leaving off the bits that supported the spring under the frame.

All was wonderful until I placed the forward spring assembly into position. The blue riding rod, under the spring, goes through the wooden sandwich frame via a hole in the wood. Here is the general arrangement.

I was immediately struck by the futility of what I had drawn. That seemingly meaningless segment across the gap has a purpose! [Red arrows] As drawn, the blue rod can take an agle from the vertical. The bottom of the riding rod would then move dramatically over to the side. Causing major force to be applied to the horn guides from the axle box being forced to the side. Premature wear and probable suspension failure would result from that sideways force. Oh no!!

That meaningless segment across the gap is support for a block, with another through hole.

This keeps the linear travel of the end of the rod limited and restricts any sideways force to a minimum. It is present on the reproduction Planet, but is incredibly hard to see, being a black object, inside another black object, without perfect illumination. We can, however, see the bolts that hold the block in place!

The Road Map Ahead

With the front spring assembly finished, I just have some minor cleanup and the chassis is complete. The first major component will have that nice check mark next to it.

Next up is the OO drive assembly. The motor and gears, with the intended oscillating handles. Drawn in OO as OO, to speed match the tender. This should prove quite interesting (well, to me anyway!). The second major assembly.

Then, the drive assembly and the scaled chassis will be married, the third major step. The Armengaud Chassis and the OO drive will be made into one.

The last major step will be the shell to fit over the lot. With this, the design shall be complete!! Hooray!

Of course, then the real fun begins, when Shapeways tells me that none of it can be built and nothing fits as intended!

Bee

[What About The Bee]

Tic in the box

With the exception of sprinkled rivet heads, this full scale chassis drawing is complete.

Onwards to phase 2

Bee

[threelink]

An absolute toure de force, Bee. I look forward to the next instalment. It's fascinating to explore the thinking behind the prototype design of anything by making a working model of it, especially very early locos and rolling stock. It's the nearest one can get to being in the head of the design engineer, and who would not want to be in Stephenson's head!

[What About The Bee]

Hi ThreeLink

Not drawn is the, ahem, three link chain and hook on the front buffer. I want that to be a real chain, therefore no need for 3D printing or presence in the model.

This has been an amazing journey so far. The chance to stand on Robert Stephenson's shoulders, to see the man at work, has been a major treat. The discovery of his thought processes is beyond exciting. Details of the LMR that would otherwise remain out of sight, hidden in plain view.

On the shoulders of giants.

I will soldier on. Thank you for the encouragement!

Bee

[threelink]

Hello again Bee. I'm not sure whether Planet was equipped with three link or five link couplings. I do not know a lot about early coupling systems but have seen illustrations showing five links and a hook, although these may just be side chains. The replica certainly has three links and, according to some photos, screw links but I suspect that the latter are a nod to health and safety issues.

[What About The Bee]

Hi ThreeLink

Taking a break from the gear train, I thought to review the period images of Planet and the planet-class locomotives I know of.

The first appears in Walker An Accurate Description of the Liverpool and Manchester Railway... 1831. This is drawn by Issac Shaw, a known good first hand observer. He shows us 5 links and a hook on center. It is unclear if this is Planet or merely a planet-class.

The only other image that shows the front chain is Armengaud. This is definitively a 3 link chain. The locomotive illustrated is La Jackson, a planet-class locomotive.

So there we have it. One type each. A 3 link and 5 link. No other image, that I know of, bothers to include the chain.

Austen would have us believe there wasn't even a buffer beam, let alone a front chain!

Bee

[threelink]

Interesting that the Walker print appears to show a coupling arrangement which would permit the hook of the coupling on a similarly fitted vehicle to be attached to the loop on the loco buffer beam from which the loco's coupling hangs, whereas the Armengaud illustration apparently shows a 3 link and hook arrangement which would only permit a vehicle similarly fitted to couple up if the hook were placed through the topmost link of the loco's coupling chain, thereby turning a 3 link coupling into a 4 link. As for Austen, well....

[Tom-378683]

Dear Bee,

That is a good spot on the Austen print of the loco, I definitely hadn’t noticed that before. I agree that looks odd - although I haven’t studied the loco development. Thanks for the eye-opener.

Perhaps he was confused with the carriage and wagon buffers which were at one point extensions of the lower sole bars on the open frames.

[What About The Bee]

Tom,

Its actually more than that. The axle for the oscillating levers on the footplate is drawn in completely the wrong place by Austen. He has it going through the firebox, when in fact that axle must be behind the firebox.

These types of discrepancies have caused me to discount Austen.

Bee

[Tom-378683]

Dear Bee,

I haven’t read this myself but Anthony Dawson’s book on the Planet I would imagine is authorative.

In any case, you need to take into account that buffers weren’t standardised until quite late in the development of things so the drawings of Planet with buffers are later…

This image shows the loco without them or a buffer beam too.

It is a major mistake to ‘discount‘ Austen in general as he provides important rollingstock insight however you may well be correct in a failing of his observation of the loco in some aspects.

With regard to buffer development, remember anything before 1832 is going to be experimental.

[Tom-378683]

Dear Bee,

If I have it correct Armengaud’s drawing was published in 1839, but when was it drawn? Mid 1830s?

Austen’s was likely drawn in Nov of 1830 or early 1831. It is worth bearing in mind there was no textbook in these early years. The things you’re expecting to be there simply took time to be developed.

Initially, 1830, no locomotives were allowed to work facing backwards, thus no need for buffers or couplings.

Obviously things had moved on by 1835. But to disregard images because they don’t include the developments you expect will distort the true picture of the development.

See the other technical drawing of Planet without buffer beam or buffers at all in my other response.

[What About The Bee]

Hello Tom

As I wait for your images to be approved, I will offer this reference for your kind consideration.

In James Walker's text, we have this image, of a Planet class locomotive going under the Rainhill Bridge. https://babel.hathitrust.org/cgi/pt?id=mdp.39015076002636&seq=8

Drawn and Engraved by Issac Shaw, known good observer.

Shaw draws a feature on the front buffer which may appear odd at first. There are two buffer beams, arranged vertically. If you now go and examine Armengaud, you will find he replicates this peculiar feature. While I agree that his drawings post date the period by a few years, Armengaud did not work in a vaccuum.

I think it reasonable to expect a feature to be present when we have good evidence for its existence. Shaw is nearly irrefutable.

Bee

Edit: Walker published in 1832. I do suppose it post dates the relevant Austen image.

[What About The Bee]

The Science Museum will offer us the date they think the Austen image was created.

https://collection.sciencemuseumgroup.org.uk/objects/co66065

1831 to 1835

Tom,

You make an excellent point. The drawing of Rocket in Mechanic Magazine, dated October 24th 1829, does not have a front buffer. I agree, it had to be developed at some time after that. I think we have a terminal date for that. 1830. Northumbrian, illustrated in Booth's book of 1830, has a front buffer. It is realistic to expect Planet, delivered AFTER Northumbrian by the same firm, to have a front buffer.

Please read my post on the previous page, with additional issues vis Planet's front buffer.

Bee

[What About The Bee]

Hello Tom

Well sir, now you have gone and done it. You have successfully changed my mind. This is in response to your post including an image of a Planet class locomotive without buffer.

Nicholas Wood portrays a Planet-class locomotive without a front buffer. In appears in the 1834 French translation of Practical Treatise..., or in this case Traité Pratique... Wood being absolutely authoritative, I yield the point. Thank you. 

In close examination, your image appears reproduced¹ from the same tome, as the chimney, with its elegant scalloped indentations, is fairly unique. From a manufacturing standpoint, such scallops could be machined today, but in the early 1830s, would be cast. Similar scallops are observed on the steam dome in the same image.

Take a moment to observe the oscillating handles on the footplate and the location of the axle, in your presented image. Then compare that correct location to what Austen provides us. I think you will observe there is a dilemma for Austen. In fairness to Austen, it took me a dog's age to work out the mechanism, even with Armengaud's mechanical drawings. Austen had to do it on the fly, without mechanical drawings.

I think this is the fascination of these old images. There is always a new detail to discover and interpret.

Bee

¹The drawing you present is from The Engineer, making it a non period drawing. I am always leary of non-period images, just as I am of non-period texts, like Thomas and Dawson. They are interpretative of the record, the artist's or author's view of the record, not the record. In the instant case, the source is Wood of 1834. Wood is the record, The Engineer is an interpretation and a smudged copy, at that.

[Tom-378683]

Dear Bee,

You’re very gallant and gracious. With the experimental nature of the LM - its just that things didn’t stand still (not meant to be a railway pun) - with additions and changes happening on something like a yearly basis.

It’s natural to choose to model Planet with the later additions - its a fine looking loco - this will also fit with the beautiful Hornby firsts which date from 1834-5.

Good luck with your project.