Talk:Mallet locomotive

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Please note: Anatole Mallet was a Swiss Engineer. From the French part of Switz. So he cannot be a Frenchman!


The diagram of the Mallet locomotive articulation is wrong. The front engine (not strictly speaking, a bogie) must translate laterally, otherwise it will derail on a curve. The wheels must describe an arc. It does not simply pivot on the locomotive centreline at the front engine centre as indicated. It must be allowed sideways play, provided by a pivot a long way from the centre, or by a bar linkage, or a pin, sprung to centre in a slot. In Baldwin Mallets, the pivot was usually near the rear, high pressure, cylinders on the fixed engine. The two carrying bogies on the diagram are irrelevant to the Mallet design: the rear one as drawn is incorrectly pivoted for the same reason as above; the front one is broadly correct. Two four-wheel engines would be sufficient to illustrate the concept.

The diagram also needs rails and some labels; a non-technical viewer cannot be expected to understand what is shown, because it does not say it is the underside of a locomotive on a curve, and the curved rails are not shown.

Verifiable references: Robins J G, 1973, World Steam Locomotives, Bartholomew ISBN 0851529232 illustrated the original 1887 Mallet articulated 0440 (last accessed 12/3/06) illustrated Baldwin's comparison to the Fairlie with illustrations from Baldwin Record 65

kind regards

Andrew Starr, Manchester UK

The diagram has been replaced with one that is more accurate. Hellbus 15:15, 30 September 2007 (UTC)

Purists claims[edit]

I have seen references in US publications to compound mallets being described as "Mallets" and simple mallets being described as "articulateds" (as if there were no others), with a clear distinction between the two. If I come across a source I will add it. Otherwise it is not a particularly important point. --Michael Johnson (talk) 02:00, 13 February 2008 (UTC)

According to "Those Amazing Cab Forwards" by George H. Harlan, Southern Pacific was careful and rigorous about the use of the terms "Mallet" and "Simple Articulated". Mallet, for them, was a compound locomotive, with a set of high pressure cylinders and a set of low pressure cylinders powered by the exhaust of the high pressures. In a simple articulated, all cylinders received the same steam pressure. They'd found that at the limit of power and traction, only the high pressure cylinders were really providing much tractive effort, so they switched. They were fairly strict about nomenclature: early articulateds were MC-1 through MC-6,standing for "Mallet Consolidation", or 2-8-8-2, and later locos were AC-1 through AC-12, for "Articulated Consolidation". AC-4 and later were actually 4-8-8-2. All Mallets were either scrapped or rebuilt as simple articulateds. — Preceding unsigned comment added by Hans42 (talkcontribs) 06:39, 17 April 2011 (UTC)

Of course their care about the distincton was due to patent liabilities; Mallet insisted on his patented designs being compound, so if you buiilt a simple expansion locomotivve and didn't call it a "Mallet" you could avoid paying him royalties. Afterbrunel (talk) 14:05, 13 August 2012 (UTC)
Well, that, and the SP didn't have any articulated engines that weren't Mallet style articulation, so it made sense for them to call them Mallet and simple; there was no risk of confusion with other types of simple articulated engines (the SP did have a Shay, I think, but in US practice those are not usually considered articulated, LeMassena notwithstanding).


I'm a bit dubious about the claim for the Virginian engines. Can we find a reference that is actually accessible on which to base this? Mangoe (talk) 19:53, 13 August 2012 (UTC)

Well, I cited the reference, of which I have a copy here. All it says is that three locomotives pushed a big train. It doesn't even state a gradient. Is that so implausible? Afterbrunel (talk) 08:56, 14 August 2012 (UTC)
Looks like Reed got that one wrong. Far as anyone else knows VGN got the 2-10+10-2s for the 2% climb out of Elmore; Rwy Age for 7 June 1924 says they ran 5500-ton trains up there with the two 2-10+10-2s shoving, then 2-8+8-2s handled the trains Princeton to Roanoke. Doesn't says anything about east of Roanoke, but I'm guessing no reason to run 2-10+10-2s on the 0.2% grade there. (And I'm guessing Reed wasn't talking about after the 1925 electrification.)Tim Zukas (talk) 17:36, 23 August 2012 (UTC)

Bissel Truck[edit]

I'm dubious about referring to the front engine as a "Bissell truck". While conceptually you could call any set of wheels and frames which pivots at one end a Bissell, the term is usually used to refer to two wheel leading trucks (pony trucks) and two or four wheel trailing trucks of the Cole or Delta type (as opposed to the center pivoted type sometimes used on tank engines). None of the references I have, either steam era or modern, call the front engine of a Mallet a Bissell. I'd suggest the article should be amended to more clearly describe how the front engine pivots on the rear, and eliminate reference to a Bissell truck.

Also, in the section on simple locomotives, it says the high pressure steam pipe "passes thru the truck pivot pin". This is wrong, both in that the steam pipe obviously does not pass thru the pin (on locomotives using this routing the pipe passes above the pin - incidently the same routing was used on the C&O compound locomotives), and in that many simple locomotives did not route the high pressure steam forward from the pivot pin, but instead used a direct routing (more or less - two swivels and a sliding section isn't exactly direct) from the smokebox to the front cylinders. Suggest either this be expanded to correctly describe the routing, or simply remove the misleading comment. — Preceding unsigned comment added by 2001:558:6030:44:1B6:90A5:EC7A:E5A6 (talk) 23:06, 19 June 2014 (UTC)

Assessment comment[edit]

The comment(s) below were originally left at Talk:Mallet locomotive/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Needs references, needs sections

Last edited at 15:36, 4 September 2006 (UTC). Substituted at 22:55, 29 April 2016 (UTC)

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