I don’t post so much on forums now, having accepted that there isn’t enough interest in the stuff to sustain a conversation. Apologies to those who encourage me to post oddball items. However, I expect that this thread will stir some interest. It concerns observations on US steam tractors.
US-made traction engines are very rare sights in the UK. I don’t know if any ever came over here new, but people are now importing old ones from the US for restoration.
I saw my second one yesterday, a 1910 Reeves. I found it very interesting, being very different from UK traction engines, which are all much of a muchness. There are some surprising features to British eyes, and I will highlight some of them here. I would like to know how well these features stood up in service.
Corrosion-wise, it’s in remarkably good condition, as far as I can see.
I was surprised how thin the boiler plate is, and also surprised by the tendency to screw important things into the boiler shell with, apparently, no compensating (thickening) plates or bosses. Some pipes and fittings are screwed straight into the shell. Apart from anything else, it’s not ideal for sealing!
To be honest, I’m not all that familiar with UK traction engine details either, but I was having a look at a Marshall portable boiler today, and the only unreinforced openings were for small plugs and inspection covers. Anything which might transmit external force had a boss riveted on.
The owner of the Reeves tractor told me that US engines used higher strength plate than UK engines. This gives lighter weight, lower cost, and easier forming of complex shapes (when hot!). The downside is that corrosion is no respecter of tensile strength, so a thinner boiler is more vulnerable to corrosion.
US makers used much wider plates. This has to be a good thing - fewer seams in the barrel. Also, note the name OTIS - I’ve never seen a steel mill’s name rolled into plate before.
One thing that impresses me about old American ‘commercial’ vehicles was the tendency not to waste time and money on unnecessary finish. Long ago, this led British engineers to be sniffy about the apparent quality of US locomotives, etc. The impression was given that if the parts that show looked bad, what about the hidden parts? However, informed comment at the time often reported that the finish and accuracy of parts that mattered was usually first class.
The lathe operator must have been in a hurry!
It’s clear that the Reeves was designed to be light and cheap to build. Its uses included direct hauling of many-furrowed ploughs. In contrast, typical domestic British traction engines must have been too heavy for direct ploughing.
Overall, I was impressed by the concept and design. They surely did the job, and were clearly lighter and cheaper than their British counterparts. This led to some cases of British manufacturers following suit, with lightweight, cheap, basic traction engines for export, such as the Marshall ‘Gainsborough’, which adopted many American tractor principles. However, I think US makers would have had a job selling their engines in the UK. They ‘looked’ flimsy (and I know appearance is probably misleading), and I’m sure some of the boiler design features would have been simply unacceptable.
Some of the ‘money-saving’ features:-
The smokebox is an extension of the boiler barrel, rather than being a separate riveted-on item, making repair more difficult when corrosion took hold (although repair is easy nowadays, by welding).
The front axle trunnion is bolted to the pressurised part of the boiler. Did this cause problems - looseness, leakage, cracks? On British engines it was usually riveted to the (unpressurised) smokebox, and the smokebox itself was usually replaceable without too much difficulty.
Marshall (I think).
I was very impressed by the wheels, which seem a good example of ‘value engineering‘. Steel or wrought iron spokes cast into iron hub and rim. However, to the unfamiliar eye, they look delicate. I know they're not.
I’m told that the cast iron rims were chilled.
I think it would have been hard to sell the idea of cast iron rims to British customers, who would not have known that American foundries could produce very tough cast iron.
I know some US makers used wheels with riveted flat spokes (e.g. Kelly, Buffalo-Pitts).
Slight over meshing of the pinion!
US steam tractor's engines often had their own bedplates, which seems better than the British arrangement of having the cylinder and crankshaft bolted separately to the boiler. Also, US engines had steam domes, while UK domestic engines didn’t. I suggested to a UK traction engine owner that these seemed like good features. He disagreed, pointing out that by having the cylinders fixed directly on the boiler, steam-jacketing was easily accommodated, steam going directly from the boiler into the cylinder with no pipework.
UK domestic engines didn’t have friction clutches. No-one I spoke to could understand why a clutch would be needed, but I found some reasons in W J Hughes’ A Century of Traction Engines. He says that if the engine was burning straw, and was driving a thresher, it needed to kept well away from the unthreshed grain, so it needed a very long belt. Having a clutch apparently allowed finer control for positioning for belt tensioning, and also allowed the tension to be altered by moving the engine without stopping threshing. Also, a clutch allowed easier starting when direct ploughing. Good points.
The Reeves engine only had single speed reduction gears. UK domestic engines usually (not always) had two or three speeds, but cheaper export models only had one.
I was surprised to see that the Reeves engine only had one safety valve. Was this normal in the US?
A minor point: the Reeves engine had a cast iron chimney, smoke box end plate, and smokebox door. All were cracked. UK engines used steel or wrought iron for these items (except the chimney base, which was CI).