Nord 4-6-2 Locomotives in France

Class 3 1151/231 A (Locobase 2750)

Data from "New Locomotives, Northern Railway of France," The Locomotive, Volume 18 (14 September 1912), p. 184. See also Edouard Sauvage, "Express Locomotives in France", Railway Mechanical Engineer, Volume 90, No 5 (May 1916), pp. 231-234.

The first of the de Glehn compound Pacifics headed the boat trains from Calais or Boulogne to Paris.

They were tall, Belpaire-boilered engines with a large-diameter trailing truck, as seen in a photograph reproduced by Roland Arzul, of [] (visited November 2002).

Edouard Sauvage, writing in the May 1916 issue of Railway Mechanical Engineer (RME), says that this batch was built when experiments with a 4-6-4 arrangement (known as Baltics) suggested a need to study that design at greater length. Hence these Pacifics were constructed. Sauvage notes the use of by-pass valves on their HP cylinders. Also the valve ports were lengthened and valve travel increased "with a notable gain of power.:" One striking example was the climb up the 1/2% grade from St. Denis to Goussaninville. Before the modifications, maximum speed for a 422-ton train was 21.7 mph (35 kph); after the mods the speed jumped to 57.2 (92 kph)!

Arzul notes that after the creation of the SNCF in 1938, the locomotives were renumbered 2.231A 1 to 20 and remained in service until 1954-1956. In later years they received an Lemaitre exhaust, smoke lifters flanking the smokebox, an ACFI feedwater heater, and a larger tender of 37 cu m (9,775-US gal) capacity.

Class Super Pacific (Locobase 1055)

Data from Gustav Reder (Michael Reynolds, trans), The world of steam locomotives (New York: Putnam, 1974); Brian Hollingsworth, Steam Passenger Locomotives (1986), MRS [Military Railway Service) French Locomotive Diagrams supplied in April 2004 by Allen Stanley from his extensive Rail Data Exchange. See also "Locomotive a Vapeur 231 C 78. 1931" submission document at [], last accessed 22 April 2019.

So-called Collin "Super Pacifics," these represented the end of the trail for the four-cylinder de Glehn compounds. Both Georges Collin and Marc de Caso are credited with the design. All of the variants had narrow, deep Belpaire fireboxes with large grated.

The class appeared in three sub-series:

3.1201 a 3.1240

This group was further divided into the first 23, which used Richardson balanced slide valves on the low-pressure cylinders, and the latter 17, which had piston valves serving all four cylinders.

3.1241 a 3.1248

For some reason, the last eight from Blanc-Misseron resorted to the mixed valve arrangement of the first 23, and incorporated two domes under a single housing.

3.1251 a 3.1291.

3.1249 and 3.1250 were built as simple-expansion, two-cylinder engines. They tested two types of valve gear. 3.1249 used the Caprotti rotary cam gear, 3.1250 tried the Dabeg rotary cam setup.

The class hauled 650 tons of boat train from Calais to Paris for many years and also ran Paris-Brussels nonstop.

OS Nock (RWC V, pl 2) says of them: "They were beautiful engines to ride, traveling always with the quiet and smoothness of a sewing machine; but because of the dusty, poor coal one always finished up as black as a chimney sweep!" Delivered with the distinctive Belpaire firebox, these locomotives received an ACFI feedwater heater in 1925, two-stage air pumps and one was fitted with the Lemaitre exhaust in 1935.

Gustav Reder and Brian Hollingsworth present different dimensions for the evaporative and superheating surface as well as for boiler pressure. Hollingsworth's data are corroborated by a reprint (mikes.railhistory.railfan.net/r043.html) of a 1935 article on the evolution of the compound locomotive. But the MRS diagram, part of a series that have proven to be very accurate, shows a larger grate area and a smaller evaporative surface area.