Talk:Duplex locomotive

message: I Added link to austrian locomotive Duplex. It uses similar principes as here described locomotives, but 70 years before them. I dont know, how to add it to this article. --Postrach 09:25, 17 October 2006 (UTC)
thread_title:  Austria 

message: In France the duplex type was made famous by the ten 2-4-6-2 (151 A) compound locomotives built in 1932 for the Paris-Lyons-Marseilles company (PLM) to haul heavy goods-trains  on the 1/125 gradient between Les Laumes and Dijon.The performance was so good the company wanted to order more engines but the nationalization of the railways (1938) stopped all projects.
These duplex engines were fitted with Lentz-Dabeg rotary cam valve motion and soon with double exhaust.  The LP cylinders drove the first coupled axle.
(Apologies, but: - Investigation on Google (try 'PLM 151A') will reveal photos. The front (LP) cyls drove on the 2nd coupled axle.
For the record, the rear (HP) cyls drove on the 5th coupled axle.)Herbgarratt (talk) 23:50, 18 May 2009 (UTC)
thread_title:  A successful french duplex 

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thread_title: Image copyright problem with Image:PRRQ1 front view.jpg

message: All 'Duplex's under this Wiki page, except the PLM 151A, have no mechanical/torsional coupling between the two power units, both of which are in the one rigid frame.
It appears implicit that the 'Duplex' concept, as innovated by Ralph P Johnson, excludes any such coupling between units. While there has been much debate as to whether or not such inter-coupling would have been advantageous, it was never included.
The PLM 151A is coupled throughout its 5 driving axles. The 2nd and 3rd coupled coupled axles are coupled by *internal* coupling rods, working on two quartered inside crankpins.
Thus, one suggests that the PLM 151A is a 'divided drive' 2-10-2, not a 'Duplex' 2-4-6-2?  —Preceding unsigned comment added by Herbgarratt (talk • contribs) 13:39, 18 May 2009 (UTC)
thread_title:  Re the PLM 151A 

message: Referencing this page:
http://www.catskillarchive.com/rrextra/odcuri.Html
there are three locomotives that are, or were, related to the Duplex Locomotives page.
As noted in the 'talk' discussion for 'locomotive duplex', the Haswell locomotive of 1862 is not a 'Duplex' in Johnson's terminology (and by reference to the graphic, we can see clearly why this is not so).  It is a balanced design, with two outside cylinders working 180-degree-opposed cranks on each side (with the sides presumably 'quartered' 90 degrees relative to each other).
The James Toleman (1892) is a divided-drive locomotive that (imho) fails the 'duplex' test because
a) only two of its four cylinders are outside; and
b) all four cylinders are ahead of the drivers (a very long piston rod being used to reach a rear-mounted crosshead (which I believe was used to allow all four main rods to be equal in length).  
This design might be compared to the George Strong 4-4-2 of a decade earlier, which used a double crosshead to drive two separate main rods on otherwise-uncoupled drivers.
There is also a picture of the Petiet 441 for the Chemin de Fer du Nord (1862) -- see also
http://www.aqpl43.dsl.pipex.com/MUSEUM/LOCOLOCO/petiet/frexp.htm
which is difficult to express in Whyte notation, and even in German style can be confusing; the design clearly passes the 'Duplex test' in that we have outside cylinders, unconjugated drivers, and a rigid frame.  I don't think, however, that Johnson or anyone else would have envisioned putting even single carrying wheels INSIDE the effective driver wheelbase... let alone three of them (and if I understand correctly, these are three separate axles presumably with LOTS of lateral motion but no radial compensation).
Wizlish (talk) 00:58, 22 May 2009 (UTC)
thread_title:  Additional candidates for "Duplex" locomotives? 

message: Pechristener (talk) 15:17, 30 October 2023 (UTC)
thread_title:  Summary in [[multiplex locomotive]]