Paris-Orleans 4-4-2 Locomotives in France

Class 3001 (Locobase 3900)

Data from M P Gonte, "Four Cylinder Compound Locomotives on the Paris-Orleans Railways", Railroad Gazette, Volume XXXIX [39], No 4 (28 July 1905), pp. 91-92 (Original article published in La Revue Generale, July 1904-translated by Baldwin's Lawford H. Fry.). See also Edouard Sauvage (On the Question of Locomotives of Great Power (Subject V for Discussion at the Seventh Session of the Railway Congress)), International Railway Congress Association Bulletin, Vol XVIII, No 12 (December 1904), p. 1667; and Edouard Sauvage, Compound Locomotives in France (March 1904), pp. 332-333, and Maurice Demoulin, Locomotive Actuelle ... (Paris: Librairie Polytechnique Ch.Beranger, 1906), pp. 117-118.

OS Nock (RWC III, pl 103) notes that these engines served as the prototype for compound Atlantics in Great Britain in the form of the Great Western's President. The PO engines were slightly bigger than the Nord de Glehn compounds from which they in turn were derived.

According to Charles Rous-Marten, writing in the January 1904 Page's Engineering Weekly, p. 29: "These fine engines will run the heavy fast expresses- between Paris and Bordeaux which, when they clear the suburban obstacles that cluster near the French capital, are booked at an average inclusive rate of over 52 miles an hour, while the various stages between stops are booked at average start to-stop speeds of 52 to 55 miles an hour over a road which has long banks at 1 in 200 to 1 in 125, and with loads ranging from 200 to 300 tons behind the tender."

Rous-Marten added an important distinction between the trains pulling stock supplied by the Compagnie Internationale des Wagons-Lits, which were limited to 100 kph (62 mph) and those consisting of P-O rolling stock, which are allowed to run up to 74 mph (120 kph).

Experience showed that these engines proved capable of pulling 350 tons at 70 mph, although regulations didn't allow operation at that speed.

Their squared-off Belpaire fireboxes, external steam pipes to the HP cylinders driving the front pair of drivers, lidded stack and slotted running board were characteristic of French locomotives of the time.

Sauvage gave two different tube counts in the two references cited above. In the Compound Locomotives, he credited the boiler with 96 finned tubes while in the later Locomotives of Great Power, Sauvage cited a count of 139 tubes.

Class 576 (Locobase 15926)

Data from the Tuesday, 1 January 2012 entry in Surzillac's Histoire de la ligne de Bretagne Sud au temps du Paris-Orleans blog, found at [] and last accessed 5 December 2014.

Forquenot's extensively produced 2-4-2 design of 1879-1887 (Locobase 7941), as modified in 1899, provided the rear two-thirds of this class of Atlantics. Retained was the 1,840-mm diameter of the drivers and the Ten-Brinck firebox with a supplementary heat-exchanger. The distances between the two driving axles and between the rear axle and the trailing truck were identical as well. To this, the 1909 rebuild added an extended front end with bogie truck and a cross-compound setup of HP cylinder on the left side of the smokebox, LP on the right.

The blogpost says the modification increased the engines' power and reduced their instability at high speed. The eight remained in service until the late 1920s.