Bar frame and plate frame

[Grovenor]

Here is a drawing of a 2-8-0 frame which might give a clearer picture.

Model Railroader that month, Sept 1972, had a blow by blow article on how to build it.

[Nearholmer]

Again though, it shows the outline, but not the construction, and I suspect it’s a model-engineering item, probably cut from a plate (laser), rather than genuinely fabricated, which is a hallmark of a classic bar frame.

 

The classic American 4-4-0 side frame was a masterpiece of simplicity: one long horizontal bar at the top, end to end of the loco, usually formed so as to descend slightly ahead of the driving axles; four cast (I think) pedestal and horn-guide sets bolted/riveted to the above; discontinues bar below the horn-guides, swept up to the front and rear of the horn-guides and bolted/riveted to the top bar; pedestal braces that acted to continue the lower bar across the openings (significantly structural, unlike the ‘keep’ on a plate frame). The two side frames were connected by cross members, including a casting acting as bearing point for the front truck/bogie. With compensation beams between the driving-axle axle-boxes, the whole thing was very flexible, yet held the track like a limpet.

 

 

Edited September 5, 2022 by Nearholmer

[Compound2632]

40 minutes ago, Nearholmer said:

The classic American 4-4-0 side frame was a masterpiece of simplicity: one long horizontal bar at the top, end to end of the loco, usually formed so as to descend slightly ahead of the driving axles; four cast (I think) pedestal and horn-guide sets bolted/riveted to the above; discontinues bar below the horn-guides, swept up to the front and rear of the horn-guides and bolted/riveted to the top bar; pedestal braces that acted to continue the lower bar across the openings (significantly structural, unlike the ‘keep’ on a plate frame). The two side frames were connected by cross members, including a casting acting as bearing point for the front truck/bogie. With compensation beams between the driving-axle axle-boxes, the whole thing was very flexible, yet held the track like a limpet.

 

You can see pretty well all those features in the photo of the Baldwin mogul being assembled at Derby, that I posted upthread.

[Grovenor]

1 hour ago, Nearholmer said:

Again though, it shows the outline, but not the construction, and I suspect it’s a model-engineering item, probably cut from a plate (laser), rather than genuinely fabricated, which is a hallmark of a classic bar frame.

Given its for an H0 model and I don't think modellers had laser cutters in 1979, piecing saw and files were more the thing or a milling machine. It may not give all of the protoyype fine details but I think it does provide what the OP was asking.

I could supply the whole article on request.

Edited September 5, 2022 by Grovenor

[rogerzilla]

GWR locos had bar framed front bogies until Hawksworth changed to plate frames.  If you see a Modified Hall from the front, the most obvious difference from the Collett Hall is the solid plate between the front wheels.

[Wickham Green too]

2 hours ago, rogerzilla said:

GWR locos had bar framed front ....

.... ends until Hawksworth changed to plate frames.

[844fan]

Hey ya'll, sorry for the delay. My head was unbearably hurting, haha yeah I have seen many bar framed GWR locos. I will go through an checkout all the replys ASAP.

[The Stationmaster]

15 hours ago, Wickham Green too said:

.... ends until Hawksworth changed to plate frames.

Well sort of.  The extension ahead of the main frames was a casting so it wasn't a plate frame nor, technically was it a bar frame. 

[jim.snowdon]

13 hours ago, The Stationmaster said:

Well sort of.  The extension ahead of the main frames was a casting so it wasn't a plate frame nor, technically was it a bar frame. 

My understanding, based not least on the writings of Holcroft and others, is that the front frame extensions are forgings.

 

[jim.snowdon]

On 05/09/2022 at 13:35, Compound2632 said:

pedestal braces that acted to continue the lower bar across the openings (significantly structural, unlike the ‘keep’ on a plate frame)

It was well into the 20th century, if not by the time they were designing the BR Standards, that the solution to persistent problems with frames cracking at the corners of the hornguide openings was to design the axlebox keeps so that they were always in tension. Otherwise, what was happening was that the frame above the hornguide opening was flexing under dynamic loading, resulting in stress concentrations at the corners turning into fatigue cracks.

[844fan]

On 05/09/2022 at 06:25, Grovenor said:

Here is a drawing of a 2-8-0 frame which might give a clearer picture.

Model Railroader that month, Sept 1972, had a blow by blow article on how to build it.

Ok this I think with the photos will be perfect. This also gives me truck connection points for them too.

 

Was not expecting such a simple question to bring up such strong response.

[sir douglas]

on bar versus plate chassis, some south american railways despised their UK built locos with plate frames because they were prone to cracking while the US built bar frames were prefered as they could flex a bit, such as the Peru Central from Lima to Huancayo, Brian Fawcett says in his book "Railways over the Andes" that the first good british locos they ever had were the "Andes" type 2-8-0's mainly because of the bar frames. There were other reasons like outside valve gear and not hiding rods and pipes away in awkward places to reach for aesthetic reasons but thats irrelevent here. 

 

Beyer Peacock example from 1946

[Morello Cherry]

The Alco on the Ffestiniog has bar frames.

 

https://www.festipedia.org.uk/wiki/Mountaineer_II

 

 

I think that if you want some photos of the frames and how it goes together then I am sure the group restoring might be able to help and they are probably one of the few groups who are likely to have a bar framed loco stripped down to the frames any time soon.

 

https://www.facebook.com/alco1265/

[Nearholmer]

I should have remembered that, having cleaned out its smokebox and ministered to it in other small ways a long time ago.

 

The thing that keeps foxing me about these various frames is that they dont look fabricated, and spme of them seem too early for welding. Were they welded by a process that I'm not aware of? Was welding used earlier than I thought? were they made somehow else? Did bar-framing progress from simple fabrication at quite an early stage?

 

TBH, I'm not expecting answers, unless someone here present is really well clued-up on US locomotive engineering practice.

[Artless Bodger]

Well, I've heard of a process called fire welding, which is what blacksmiths did, heat two pieces of metal and hammer them together into one piece. In the wrought iron production process, iron bars were cut, stacked and heated before hammering them into a block, then hammered or drawn into a bar, re-cut and the proces repeated, the more the better to provide the fibrous structure for ductility. An important process for steel for high quality sword blades too I believe.

[jim.snowdon]

2 hours ago, Nearholmer said:

I should have remembered that, having cleaned out its smokebox and ministered to it in other small ways a long time ago.

 

The thing that keeps foxing me about these various frames is that they dont look fabricated, and spme of them seem too early for welding. Were they welded by a process that I'm not aware of? Was welding used earlier than I thought? were they made somehow else? Did bar-framing progress from simple fabrication at quite an early stage?

 

TBH, I'm not expecting answers, unless someone here present is really well clued-up on US locomotive engineering practice.

The attraction of bar frames for the Americans (and probably others) was they could be assembled from relatively small wrought iron (later steel) sections and castings, without the need for large rolled plates. A lot of early US railway engineering was relatively primitive in relation to what we have become accustomed to simply because in the early days they lacked the heavy industrial facilities. There are other examples - archbar (or, to us, diamond frame) trucks, stub points, for example. Having adopted them, they stuck with them,  and fabricated bar frames served them well, but with increasing problems as locomotives grew in size and power. The bugbear with them was their ability to work loose, which isn't exactly desirable in any machine. That led to the adoption of one piece cast steel frames with, in later days, the cylinders cast integral with the frames. The down side of one piece cast steel locomotive beds, as they called them, is that you need some distinctly large machine tools in order to be able to handle them, as well as some interesting machining techniques, particularly for jobs like boring cylinders. That was less of an issue for the Americans than it might appear since so much of their locomotive construction was subcontracted to a relatively small number of companies, notably Alco, Lima and Baldwin, for whom the investment in machine tools and workshops was justified by the scale of production.

[Cunningham Loco & Machine Works]

The upper portion of the frame on that ALCo is neither cast nor welded, but was instead forged in one piece, a means often employed on these smaller engines.

 

Further details forthcoming.

[eastglosmog]

There is a drawing of the bar frames of the WD Baldwin on p205 of R Gratton and S. R. Band's "The Ashover Light Railway", Wild Swan 1989, ISBN 0 906867 72 X .

[tomparryharry]

I think the largest 'cast' bar frames were the South African class 25.  These were made in the 'States, and exported. It's been a long time, but it was in a foundry journal.

 

Edit: The Pennsy S1 holds the record for the largest bar frame, being some 77 feet long. 

 

On a lighter note, the people replicating the PRR T1 intend to compete for the Mallard record. 

 

There is no truth in the rumour that the NRM intend to hollow out an LNER tender, and install a pannier to help things along..... 

Edited October 6, 2022 by tomparryharry
More information.

[rodent279]

Here is a comparison shot from similar angles of plate framed 9F 92220 Evening Star, at Didcot in March 1983:-

 

 

and bar framed DR class 50 2-10-0 50 3610, at Berlin Schöneweide in 2018:-