Spitfire's G3 Workbench

[Spitfire2865]

The motion is finished. And it is SO satisfying playing with it in the simulation. It will look perfect once I actually get around to building it.
Ive also made a start on the engine truck.

Everything seems fairly straight forward aside from one specific part which I cant find reference to anywhere in my drawings besides the individual part drawings and an overall sideview which hides most of it.

This photo views the right side and the mystery bits are highlighted. The forked part clearly bolts to the frame there due to the hole patterning, and the downward angled strap hangs forward and down according to the side view line drawing, however the center bolster mount has a hole that "almost" matches the lower strap's hole. (I account calculator rounding limit to that fraction of a millimeter misalignment)
Now my issue is in operation, the swing links will rock the frame in relation to that top bolster mount(which is mounted to the cylinder casting), thus changing the angle between the relevant holes.
Ive yet to find an assembly drawing that shows these parts, nor a part drawing of anything that could link them.
Odder still, I have yet to model one part of the Engine Truck, a brace that goes from the ends of the top frame to the center bolster. This would cross where these two holes should line up.
This isnt even considering how when the truck turns, the distance changes.
Has anyone ever seen an arrangement like this? Is this meant as some form of sprung self centering aid that Im just missing a drawing for?

 

[Peter]

Has anyone ever seen an arrangement like this?

Hi Trevor,

It is a four wheel Bissell truck, similar to that used by Beyer, Peacock in the 4-4-0T built for the Metropolitan Railway.

In my copy of A History of the American Locomotive Its Development: 1830–1880 9780486238180 (the 1968 edition of American Locomotives: An Engineering History: 1830-1880 republished by Dover Publications Inc in 1979), on pages 422 to 426, regarding the Rogers 4-4-0 ca 1865, there are drawings of which two should assist you. They are Fig 222 and Fig 223.

I cannot give you the pages in your edition of this book.

Peter

 

[Jon Nazareth]

Trevor
It's a good thing that I can't use cad the way you do. If I could, I'd be building all sorts of 1860's engines .

Well done.

Jon

 

[Spitfire2865]

Hi Trevor,

It is a four wheel Bissell truck, similar to that used by Beyer, Peacock in the 4-4-0T built for the Metropolitan Railway.

In my copy of A History of the American Locomotive Its Development: 1830–1880 9780486238180 (the 1968 edition of American Locomotives: An Engineering History: 1830-1880 republished by Dover Publications Inc in 1979), on pages 422 to 426, regarding the Rogers 4-4-0 ca 1865, there are drawings of which two should assist you. They are Fig 222 and Fig 223.

I cannot give you the pages in your edition of this book.

Peter

Thanks for that. I honestly forgot I had the book!
I see the arrangement in the book, but something seems wrong.
In the books example, the angled strap points forward and up and looks to be solidly attached to the bogie mount.

However my drawings clearly show that strap forward and down, plus its hinged at both ends. I have no reason otherwise to mistrust these drawings.
Also, how would it swing and lean if its constrained by a pin at both ends?

 

[Peter]

Thanks for that. I honestly forgot I had the book!
I see the arrangement in the book, but something seems wrong.
In the books example, the angled strap points forward and up and looks to be solidly attached to the bogie mount.
View attachment 89663
However my drawings clearly show that strap forward and down, plus its hinged at both ends. I have no reason otherwise to mistrust these drawings.
Also, how would it swing and lean if its constrained by a pin at both ends?

Hi Trevor,

It swings in the same manner as a two wheel Bissell truck but with four wheels.
It leans in your case by swing links and in my example through inclined planes.

Extracts from Fig 222 and Fig 223.



Best regards,

Peter

 

[Peter]

Hi Trevor,

Have you come across this document at:

http://cprr.org/Museum/Books/I_ACCEPT_the_User_Agreement/Jupiter-119_Appleman_NPS.pdf

Being the study into the feasibility of recreating 119 and Jupiter for the National Parks Service, it details the sources of the required information and includes copies of some drawings etc.

Best regards,

Peter

 

[Peter]

Hi Trevor,

Here is a drawing of a four wheel Bissell truck as supplied by Beyer, Peacock & Co.



Best regards,

Peter

 

[Spitfire2865]

Hi Trevor,

Have you come across this document at:

http://cprr.org/Museum/Books/I_ACCEPT_the_User_Agreement/Jupiter-119_Appleman_NPS.pdf

Being the study into the feasibility of recreating 119 and Jupiter for the National Parks Service, it details the sources of the required information and includes copies of some drawings etc.

Best regards,

Peter

I have found that file before but never read if through fully.

Looking at your bissel truck design, I see the bogie is pivoted at the frame towards the drivers. However on my truck, there is no lateral motion aside from the swinging links, having a central pin akin to a standard bogie.
Should this give enough sideways motion to negotiate reaonable turns? I might have to redesign the center section to allow a bit of side to side sliding to push the radius itll negotiate. Cant easily test it in the simulation.

 

[Steph Dale]

Trevor,

On the prototype, the swinging links would be a very effective way of putting a centring force on the bogie, while allowing it to rotate. The pivot over the centre of the bogie still needs to rotate (a little) and carry the weight of the front of the loco. It's intriguing to see the strut from the back of the cylinder block go down to the bogie pivot, but of course US locos typically use the boiler as the main structural element, with everything attached to it. In the UK the mainframes would be doing the same job.

This can be made to work in a model; all the Martin Finney LSWR 4-4-0s (and the M7, in reverse!) use a similar approach to reduce the rotation in the front bogie so that the mainframe which is behind the bogie wheels can be modelled to full profile.

Steph

 

[Spitfire2865]

This can be made to work in a model; all the Martin Finney LSWR 4-4-0s (and the M7, in reverse!) use a similar approach to reduce the rotation in the front bogie so that the mainframe which is behind the bogie wheels can be modelled to full profile.

Steph

Do you have a photo of this arrangement? I want to be able to get this loco around pretty rediculously tight radii, and the short wheelbase should suit, however I may have to design into the bogie a sprung sideways slide to push the bogie out on a curve, akin to the bissel truck posted by Peter. Theres plenty of room under the cylinders for it, but getting it redesigned will be a chore, but not inpossible.

 

[Steph Dale]

Errr, yes; I can take a photo of my M7 tomorrow.

I'm not sure how it will help you though, as the geometry and centres of rotation will be defined by the model and curve you want the loco to take; it won't be as simple as copying what Martin designed.

But yes, I'll try and grab a photo before the Grand Prix starts...

Steph

 

[Spitfire2865]

Errr, yes; I can take a photo of my M7 tomorrow.

I'm not sure how it will help you though, as the geometry and centres of rotation will be defined by the model and curve you want the loco to take; it won't be as simple as copying what Martin designed.

But yes, I'll try and grab a photo before the Grand Prix starts...

Steph

While it may not be a copy and paste arrangement, Im not particularly good with the whole geometry, so seeing how a model may get around the issue could help. Especially getting around model sized curves. Not sure if It would be as easy as loosening the tolerances or having to redesigning the center bogie to slide as well as pivot and swing.

 

[Steph Dale]

Trevor,

I tried taking photos of my M7 and there's too much in the way to pick out anything clearly - I really didn't want to take the model apart. However, @Dikitriki has built a test etch of an LSWR L12, which has the same features. If you look at this page you'll see the bogie with bracket/pivot attached and further down a shot of the chassis spacer with peg: Finney7 LSWR L12

So it works, and is a 'proof of concept' for your model - yours will naturally be different...

Steph

 

[Brian McKenzie]

View attachment 89662
. . . . and the downward angled strap hangs forward and down according to the side view line drawing. . . .

I'm wondering if your downward angled strap shouldn't be rotated about its length axis to rise upwards, so that the two parts you've circled in red fit together, despite the side view suggesting otherwise. This then brings the arrangement closer to the plans uploaded by Peter - mindful that I'm slightly nervous of the draughting quality in your sourced side view, message #144.

The angled strap appears to beef up the strength for the pivot point, or supply the actual pivot point of the truck's radius arm. The loco's bar frame is rather slender in this vicinity, and filled with valve gear internally, thus not offering a solid fixing point. Peter's views show a stretcher bar, or a sandwich of two bars, across the loco bar frame giving support to the angled strap. Do you have further information showing this attachment point?

While it might seem inconceivable, I did wonder if there is a pivot attached to the loco frame for the truck's radius arm. By rotating the angled strap under discussion, as suggested, might this then form a swing-link connection, albeit one in a horizontal manner? A bit scary, but Trevor's CAD doesn't hint at firmly bolted joints.

Brian McK.

 

[Peter]

I'm wondering if your downward angled strap shouldn't be rotated about its length axis to rise upwards, so that the two parts you've circled in red fit together, despite the side view suggesting otherwise. This then brings the arrangement closer to the plans uploaded by Peter - mindful that I'm slightly nervous of the draughting quality in your sourced side view, message #144.

The angled strap appears to beef up the strength for the pivot point, or supply the actual pivot point of the truck's radius arm. The loco's bar frame is rather slender in this vicinity, and filled with valve gear internally, thus not offering a solid fixing point. Peter's views show a stretcher bar, or a sandwich of two bars, across the loco bar frame giving support to the angled strap. Do you have further information showing this attachment point?

While it might seem inconceivable, I did wonder if there is a pivot attached to the loco frame for the truck's radius arm. By rotating the angled strap under discussion, as suggested, might this then form a swing-link connection, albeit one in a horizontal manner? A bit scary, but Trevor's CAD doesn't hint at firmly bolted joints.

Brian McK.

The angled strap in question, in my opinion, at its lower point forms the pivot. It is located laterally with a beam attached to top of the two frames of the Rogers locomotive and an inverted T strap on wood burning locomotive number 44 mentioned below.

The “radius arm” is formed by the V shaped strap on the Rogers locomotive and the triangular plate on locomotive number 44 connecting this pivot with the rear of the truck.

This is supported by drawings of another locomotive. They are of wood burning locomotive number 44 as illustrated in the book by G Weissenborn, American Locomotive Engineering and Railway Mechanism.

I include an extract from page 109 of the document by Roy E. Appleman at:

http://cprr.org/Museum/Books/I_ACCEPT_the_User_Agreement/Jupiter-119_Appleman_NPS.pdf

Details of the frames and cross straps are shown on pages 106 (upside-down) and 115.

A side section is on page 117.

From the drawings provided for the Rogers 4-4-0 in Colburn’s Locomotive Engineering and The Mechanism of Railways and the wood burning 4-4-0 number 44 in Weissenborn’s American Locomotive Engineering and Railway Mechanism, it would appear, in my opinion, that the drawing in message #144 may be in error.



Best regards,

Peter

 

[SimonT]

Trevor,
below is a link to the F7 instructions for the M7. Hopefully page 4 should show you how the bogie works.
http://finney7.co.uk/Downloads/SR_Drummond_M7_A3_Pages.pdf
Simon

 

[Spitfire2865]

The angled strap in question, in my opinion, at its lower point forms the pivot. It is located laterally with a beam attached to top of the two frames of the Rogers locomotive and an inverted T strap on wood burning locomotive number 44 mentioned below.

The “radius arm” is formed by the V shaped strap on the Rogers locomotive and the triangular plate on locomotive number 44 connecting this pivot with the rear of the truck.

This is supported by drawings of another locomotive. They are of wood burning locomotive number 44 as illustrated in the book by G Weissenborn, American Locomotive Engineering and Railway Mechanism.

I include an extract from page 109 of the document by Roy E. Appleman at:

http://cprr.org/Museum/Books/I_ACCEPT_the_User_Agreement/Jupiter-119_Appleman_NPS.pdf

Details of the frames and cross straps are shown on pages 106 (upside-down) and 115.

A side section is on page 117.

From the drawings provided for the Rogers 4-4-0 in Colburn’s Locomotive Engineering and The Mechanism of Railways and the wood burning 4-4-0 number 44 in Weissenborn’s American Locomotive Engineering and Railway Mechanism, it would appear, in my opinion, that the drawing in message #144 may be in error.

View attachment 89704

Best regards,

Peter

Yes, that is my current theory. However, something odd is the radius arm has no means of constraining itself and at approx 10° from straight it will collide with the valve gear.
So Ive added a slot in the bogie mount to constrain that beam to 9° either side to hopefully avoid any strike.
Im also playing around with adding a radiused slot in the bogie to give some sideways motion, that way hopefully the bogie pivots around that radius arm aft pin rather than the center bogie.
Havent gotten it perfect yet, but its certainly better.

 

[Spitfire2865]

Well quick update.
Took time off from the loco to make a start on the tender.

Strangely I cant see from the drawings how the truck springs actually...work...
They press onto the axleboxes, however the rear ones are solid with the archbar. The front do float in the archbar though.
But aside from the axlebox bearing surface, there is nothing for the tender frame to bear down onto for the rear.
Hmmm....

 

[Spitfire2865]

Been working on the cab drawings. Id like to have it all lasercut in 1mm wood sheet. 3 layers per side should give enough structure to the finished cab.
Quick mockup in the Solidworks assembly.

And ALL the parts for the cab. Almost all drawn up this evening. Quite exhausting work.

Does anyone know someone with a lasercutter who would be willing to do 1mm thick wood?

 

[Spitfire2865]

My planning is soon to come to a close. Im almost done with all the designs. Ive only a few select parts still to design such as pilot, lamp, brakes, bell, whistle, and injector(which I was surprised to find was originally present in the loco as built in 1869 according to original photos and patent dates).

And I even got a bit of practical modelling done! Ive made the two beams that make up the pilot crossbeam.
Its not much, but at 113mm wide, marks the widest part of the locomotive aside from the roof. And of course I havent any wood of the right size but plenty of other various sizes so I was able to make up both beams from thinner sections.

I think Ill begin laying out all the etches I need and send the pattern off.

I still have to count all the fittings Ill need. I know Ill need over 500 1mm rivets to put the tender together. Most will be cosmetic, but quite a number will actually be functional fixings.