GWR sandwich and double-framed locos

Reading 'The Dukedog Story" (a ca. 1980s-ish publication by the Bluebell Railway) Tom Gomm makes the following assertion:

"Despite the improvements in normal bull-head permanent way, however, the old track [i.e. baulk road - TJ] was retained on many routes even after the disappearance of the broad gauge and its lack of resilience prolonged the construction of sandwich and double-framed locomotives long after their disappearance from other companies' lines."

(My emphasis).

To which my questions are: does this sound plausible? And is this documented as the reason for the GWR constructing many such locos at the end of the nineteenth and beginning of the twentieth century, or was there some other reason?

(Hoping maybe @Jimc might chip in).

Tom

 

Was it Brunel who didn’t like the Coffee at Swindon? No idea what he thought of the sandwich’s though (apologies Tom)

 

I always understood the issue to be it was excessively stiff (weren't the baulks on piles sometimes). Would a sandwich frame have more flex in it?

Presumably a brunel-designed sandwich would be ground-breaking ambitious design which may or may not have worked in practice with the materials available at the time. I think he'd come up with something like a 14' long rhubarb and anchovy gluten-free ciabatta.

 

Ahrons asserted that the Great Western used sandwich frames much later than other companies principally because the engines ran with less vibration on the baulk road. However Gooch abandoned it in favour of plate frames for new broad gauge locos after 1856 yet continued to use sandwich frames on his narrow gauge locos which is rather the opposite to what one might expect in view of the foregoing assumption.

However renewals of sandwich frame locos continued to be built with sandwich frames, even when the replacements were completely new engines. Then Dean adopted sandwich frames for several new classes in the late 1880s (Barnum 2-4-0s, 3521 0-4-2Ts, many of which were convertibles, and a couple of big convertible 2-4-0s); possibly this decision was prompted by smoother riding on the baulk road as many of them were buillt to the broad gauge.

I think the double plate frame locos were just a consequence of the generous bearing surfaces Swindon always used when combined with the old forged crank axles then used requiring fillets or webs to avoid sharp angles leading to cracking.

 

There is a witty line in 'The Railway. British Track since 1804' that refers to baulk track being rectified of some of its rigidity. 'Brunels troublesome piles were cut off and abandoned'
An excellent read by the way.

 

I wasn't around then... Its always tricky finding out the reason why decisions were made, not recorded in minutes...

The baulk road, with every rail supported (hopefully anyway) over its full length was supposed to be less springy than chaired track which of course is only supported on every chair and has a minute degree of flexibility in between. There are an awful lot of stories about pros and cons, but I find none of them especially convincing. I suspect the biggest advantage of the double framed locomotives, in those days of dubious lubrication, was simply a lot more bearing surface. I'm away from my library, but I think Holcroft tells that if there was a hot box on a double framed single the driver would adjust the springs so that its mate on the other side of the wheel was doing all the work, chuck in plenty of oil and continue carefully.

Note that sandwich frames and double frames were different technology, although both could be present. Sandwich frames had two thin plates with a layer of oak in between, instead of a single thicker plate of steel (exactly analogous to composite construction on boats and aircraft nowadays), double frames were frames each side of the wheel, whether sandwich or plate. Sandwich frames were presumably lighter. To my knowledge there are no GWR sandwich frames left.

Baulk road was only on piles in the very very early days, I think they were abandoned long before the GWR reached Bristol, maybe even before Maidenhead!

 

That is correct, the piles were only used on the section east of Maidenhead and were probably cut off before the line extended westward.

Brunel was dissatisfied with the stone sleepers Stephenson used and although the longitudinal timbers and transoms were more expensive he hoped to counter that cost by being able to use a much lighter form of specially designed rail of only 43 lb (Stephenson was using 65lb). At that time cross sleepers of timber weren't considered suitable for permanent track, although Stephenson did use them on embankments where settlement was expected to continue.

West from Maidenhead Brunel used 62 lb rail and much heavier section baulks.

 

Obviously not original examples, but Fire Fly has sandwich frames, and I think Iron Duke does as well. In the case of Fire Fly, they are marine ply rather than oak. Not sure what the mortal remains of the OWW thing contain, have a feeling it's a 'normal' double frame.

 

Hmm, just as well she'll never have to run any distance at any speed then (and thus in that context a reasonable decision) but the difference in strength between the original end grain oak and marine ply will be considerable.

 

Firefly's frames would have used ash, Iron Duke might well have used oak for its frames.

252 did (does?) indeed have plate frames.

 

They are definitely marine ply. Off hand I'm not sure what was used for Iron Duke, given its background I wouldn't be surprised if they were oak, although the material does of course have its issues. I have a feeling however that they were made from something rather less durable.

 

In the preceding post I was referring to the original locos.

 

Ah right, I understand the original Fire Flies did indeed use oak, unless this is a latter-day assumption.

 

End grain oak was in use for the last sandwich frames, Holcroft saw a set being made and described the process. I just assumed (foolish) all were the same.

 

According to Ahrons the earliest Gooch locos used ash planks.

 

Thanks all. So the general consensus on the frames is that - for double frames at least, the baulk road is a bit of a red herring and it is probably more to do with gaining sufficient bearing surface area.

On sandwich frames - I recall Holcroft noting that the bolts through were heated to red heat before being put in place, the objective being to char the wood and prevent the tannins in the oak from causing later corrosion to the bolts. Those early craftsmen certainly had a detailed knowledge of the materials available to them.

Tom

 

Would a secondary object of heating the bolts be to pull the frames together more tightly as they cooled and shrunk, or would the nuts have been put on and tightened once the bolts cooled?

 

The shift from Ash to Oak is interesting. Ash is used where springiness is required eg Morgan bodywork framing. I wonder if they started off looking for spring and then changed to sheer strength.

As for plywood - they built mosquitos out of the stuff, and plenty of buildings held up with cross-laminated timber, if used properly, laminated timber can be very strong.

 

I have been reading about the resilience of our contemporary technological culture if it collapsed. You highlight a major cause of concern. Although much is known about the development of technology in the industrial period, the knowledge of the craftsmen using even quite recent manufacturing techniques is largely missing. It seems from my limited reading that at best a reversion to the Middle Ages is probable.

 

I find that unduly pessimistic, though I acknowledge your concern about skills. The difference is in the ability society has developed to perform very large organisational feats, and the skills that have developed there. Those soft skills would, I believe, provide significant mitigation against what you describe.