Paris-Lyon-Mediterrannee 4-6-2 Locomotives in France

Class 231 E 1/231 E 2 (Locobase 13401)

Data from WikiPLM at [], last accessed 8 November 2011.

The four-cylinder simple-expansion engines of the 6 102 series (Locobase 13400) were redesignated 213 A 1 in 1923. Soon after that update, the entire class began its conversion to a four-cylinder compound system that used a slightly smaller boiler; ; the original simple-expansion trial horse (Locobase 10737) joined the class in 1928. PLM-Oullins began the program in 1925 and was joined by the Compagnie GTnTrale de Constructions et d'Entretien des MatTriels de Chemin de Fer (CGCEM), which completed its portion in 1927. The Ateliers du Nord (ADN) at Haumont finished the makeovers in 1927-1928.

In the 1930s, 62 of the machines received ACFI type RM feedwater heaters. 9 others were fitted with Caille PotoniT type RS, which resulted in slightly higher weights.

Class 231 F 231 / 231 G 231 (Locobase 13403)

Data from WikiPLM at [], last accessed 8 November 2011. See also George Carpenter ("Was there a Conspiracy [against Andre Chapelon]?" SNCF Society Journal Number 131/132, Autumn 2008, archived at [] . In addition to a selection of 231 D-class locomotives (231 D 2, 11, 29, 30, 46, 47, 57, 116-118, 121, 130, 135, 138, 139, 141, 142, 145, 149, 152, 166 in 1931 and 231 D 13, 36, 123, 158 in 1932), Creusot produced 55 new Fs in 1931-1932.

This class of converted Ds and the newly built Fs were refitted with a Dabeg "economiser", which occupied some of the superheater flues and was credited with 25.48 sq m of reheating surface. The retrofit tested two installations, one with separate elements in most of the rebuilt locomotives and one with mixed elements arranged in a series with the ACFI Series RM reheater. The latter was fitted to the Creusot-built set of new F-class Pacifics.

When the Fs were updated with four arch-tubes with 45 litres (2,745 cu in) that may have been similar to thermic syphons, they also had many innovations in steam-circuit redesign (e.g., wider cross-sections in the LP circuit) as well as several other features wider cross-sections in the LP circuit, double-exhaust, mechanical lubrication, and smoke lifters.

According to Georges Carpenter, these engines and other PLM rebuilds fell short of what might have been accomplished had the PLM not resisted Chapelon's ideas. Even so, these engines and the K rebuilds "...gave a maximum drawbar h.p. 36% higher at 100 km/h and 63% higher at 120km/h than the standard 231 D of 1923."

Class 6 001 / 231 C (Locobase 10737)

Data from "Pacific Type Locomotives, PLM Ry," The Locomotive Magazine, Volume XV [15] (15 November 1909), p. 214, supplemented WikiPLM at [], last accessed 8 November 2011. See also "Four-Cylinder Compound Locomotive, Paris, Lyons & Mediterranean Ry." Locomotive Magazine, Volume 20 (15 September 1914), p. 234.

In the late "aughts", the PLM decided to compare Pacifics by pitting a superheated simple locomotive design (Locobase 10738) to this non-superheated compound locomotive. LM's details spell out the trial profile, which ran just under 100 miles (160 km) from Laroche and Dijon on the Paris-Marseilles main line. The first 133 km featured mostly gentle and rising grades culminating in a 15-mile (24 km) stretch of 1 in 125 (0.8%) until it reached Blaisy Bas at the summit, 319 m (1,045 ft) above Laroche. Then the line dropped 157 m (516 ft) to Dijon, which lay 27 km (16.75 mi) away.

The simple engine run up to Blaisy Bas pulled 456 tons (415 tonnes) in 98 1/2 minutes. It consumed 3,870 kg (8,532 lb) of coal and developed 1,178 drawbar horsepower. Over the same route and pulling 487 tons, the compound of this entry took 87 minutes, developed 1,246 dbhp, and using up 3,116 kg (6,870 lb) of coal. Trailing smaller loads, the compound showed even better economy. Results like these showed that the "compound engine gives higher speed, greater power with less coal."

The compound variant won the first round and confirmed the PLM's preference for double-expansion; a group of 40 more fitted with superheaters was produced in 1911 (Locobase 2535).

The 6100 was later superheated; see Locobase 13398.

Class 6 001/231 A 1 (Locobase 10738)

Data from "Pacific Type Locomotives, PLM Ry," The Locomotive Magazine, Vol XV (15 November 1909), p.214, supplemented by WikiPLM at [], last accessed on 8 November 2011. "Four-Cylinder Compound Locomotive, Paris, Lyons & Mediterranean Ry." Locomotive Magazine, Volume 20 (15 September 1914), p. 234; and Railway Engineer, Volume 34, No 8 (August 1913), pp. 253-254.

This was the simple-expansion trial horse used to compare superheated simple to superheated compound locomotives. Piston valves measured a relatively small 220 mm (8.67 inches) in diameter. RE's analysis (author unidentified, but possibly the journal's editor S Richardson Blundstone) noted the doubled load placed by four cylinders in the simple setup vs the two "boiler cylinders" (high pressure only) of the compound. At maximum cutoff of 80%, the steam demand was 52% higher than the compound. "This large excess volume", continued RE, "over-compensates for the reduced pressure of the single." Trial results not only demonstrated lower fuel and water consumption, but also faster acceleration at all speeds.

Then RE's reporter turned to superheating and uttered what Locobase regards as a less defensible conclusion. He argued that the "chief value" of the 6001's trial was that it showed "there is NO saving of condensation by the use of superheated steam, volume for volume and pound for pound equivalent of water delivered to the valve chests."

Locobase suspects that RE did not properly assess the role of supeheat temperature. Beyond a relatively low difference between saturated steam temperature and superheater steam temperature (which consistently increased), the latter's product gained its economy from the almost total lack of entrained moisture. Perhaps most telling as a counter argument, very few trunk-line French locomotives--simple or compound--delivered after this set of trials were not superheated.

The compound prototype is described in Locobase 10737. Compounding proved irresistible to the PLM (as it was to most French express-locomotive designers), so the 6101 was converted to a compound in 1928; see Locobase 13401.

6101 itself went through several designations -- 231 A1, 231 E1 -- before arriving at 231 H8.

Class 6 001/231 C - superheated (Locobase 13398)

Data from WikiPLM at [], last accessed 8 November 2011.

After the 6100's trials delivered the verdict that four-cylinder compounding was the proper course to take in developing new Pacifics (Locobase 10737), the PLM superheated the 6100 (using the same boiler design as the 1001-class Mikados--Locobase 13380-- of the same year) and increased the HP cylinders' diameters. The shops also modified the exhaust.

In later years, the exhaust would be modified again (1920), the shops would install an ACFI reheater in the steam circuit between the HP and LP cylinders (1926), and smoke-lifters would be fitted in 1931.

Class 6 011/231 C (Locobase 2535)

Data from Gustav Reder (Michael Reynolds, trans), The World of Steam Locomotives (New York: Putnam, 1974); and AERJ (Volume 90, #5, May 1916), supplemented by WikiPLM at [], last accessed 8 November 2011. See also "Four-Cylinder Compound Locomotive, Paris, Lyons & Mediterranean Ry." Locomotive Magazine, Volume 20 (15 September 1914), p. 234; and "4-6-2 Compound Superheater Express Locomotive, Paris, Lyons and Mediterranean Ry", Locomotive Magazine, Volume XXIII [23] (15 February 1917), pp. 26-29.

Henschel & Sohn of Germany produced the first 20 (works numbers 10844-10863) because of a lack of available capacity among French builders.

These were the compound half of the superheated batch of engines built by the PLM in 1911 to test superheated against saturated-steam locomotives. Piston valve diameters measured 240 mm (9.4 inches) for the HP cylinders, 360 mm (14.2 inches) for the LP cylinders.

Compound or simple, the trials showed 9.6% lower fuel consumption with superheaters. Further testing in 1913 compared the two superheated contenders and the compound engine burned 25% less coal. Hauling a 646-ton train at 49.7-55.9 mph average speed, the test engine -- 2604 -- achieved 2,425 IHP and 1,604 drawbar HP as measured on the dynamometer .

Marechal's concise conclusion from this exacting comparison was to state that the PLM had "abandoned the employment of simple expansion and the pressure of 12 kg per sq cm [170 psi or 11.75 bar]." LM's report added that the compounds' success shouldn't have surprised observers as it was "only such as has been recorded time and again in years past."

So what delayed acceptance? "[T]he matter has been obscured by so many side issues, e.g., numbers of cylinders, superheating, etc., etc. that the basic principle of a well-designed compound over an equally well-designed simple engine for working heavy and fast trains under parallel conditions has been too frequently forgotten or neglected."

(Locobase notes a key assumption in LM's conclusion is that a simple-expansion locomotive with larger cylinders would not have proved more economical than the four-cylinder locomotives tested by the PLM.)

After this, 230 compound Pacifics were ordered in 1921 with 55 more following in 1931. 30 were later retrofitted with a boiler pressed to 285 psi and 284 others received more limited upgrades. The last of these engines ran until 1969.

Class 6 051/6172/231 B 1 (Locobase 13399)

Data from WikiPLM at [], last accessed 8 November 2011.

Although the 6 172 series of four-cylinder simple-expansion Pacifics (Locobase 2534) did not prove to be failures, the PLM strongly preferred a four-cylinder compound layout. Beginning in 1917 the PLM-Paris and PLM-Oullins shops converted the entire class to the standard compound arrangement over the next seven years.

Other than a slight weight gain, the changes were limited to the steam circuit and the use of 240-mm (9.4-inch) piston valves for the HP cylinders and 360-mm (14.4-inch) piston valves for the LPs.

They were fitted with smoke-lifters and feedwater heaters in 1931-1937.

Class 6 102/ 231 A 1 (Locobase 13400)

Data from WikiPLM at [], last accessed 8 November 2011. 6102-6131 from Henschel & Sohn in 1911 and 6132-6171 Constructed 1912 by SociTtT frantaise de constructions mTcaniques (Cail) in 1912.

Identical to the four-cylinder simple-expansion engines of the 6 172 series that appeared in the same year (Locobase 2534). Each cylinder was served by its own 220-mm (8.67-inch) piston valve.

While the 6 172s were superheated beginning in 1917 (Locobase 13399), this class retained its simple-expansion layout until 1925. At that point they were rebuilt as compounds using a different boiler and placed in their own 231 E 1 class; see Locobase 13401.

Class 6 172 (Locobase 2534)

Data from tables by Edouard Sauvage in RME (May 1916), supplemented by WikiPLM at [], last accessed 8 November 2011.

Unusual for a French engine in that it was a four-cylinder simple-expansion layout. Each cylinder was served by its own 220-mm (8.67-inch) piston valve. Originally built to show the advantages of superheating and used to compare against superheated compounds, the trials measured 2,425 IHP on one engine as it pulled a 646-ton train.

Despite any such successes, the PLM preferred four-cylinder compounds and began converting this class (and renumbering it) in 1917; see Locobase 13399.The class worked the Paris-Lyon-Marseilles expresses for over 30 years.

Class 6 301/231 D 1 (Locobase 13402)

Data from WikiPLM at [], last accessed 8 November 2011. Creusot produced the 6 301-6 330 in 1918-1922, 6 331-6 360 in 1922-1923, and D 181-D 230 in 1925-1926. Franco-Belge added a single batch of 20 (6 461-6 480) in 1920-1922. Saint Chamond built the 6 411-6 460 in 1922-1923 and the 6 361-6 410 in 1923-1924. Schneider finished the new-builds with 50 locomotives--231 D 181-230--delivered in 1925.

As the 6 172 series was being converted to a four-cylinder compound system (Locobase 13399), the PLM built many more from scratch. These used a higher-pressure boiler with fewer tubes and flues. 240-mm (9.4-inch) piston valves fed the HP cylinders and 360-mm (14.4-inch) piston valves supplied the LPs.

Several different reheaters were fitted in the steam circuit between the HP and LP cylinders. Various locomotives used ACFI system RS, ACFI system RM, ACFI Caille Pontoni T type RS, Dabeg, or Westinghouse type 2 BZ.

Most of the class was rebuilt as 213 F engines.

Ten of the Ds were updated in 1936-1937 using Andre Chapelon's ideas on improving steam-passage streamlining. These Gs (G 15, 16, 17, 61, 125, 133, 146, 157, 170, 178) had wider cross-sections in the LP circuit, double-exhaust, mechanical lubrication, and smoke lifters.

Class 6221/231 C 21/5-231 C 21 (Locobase 20534)

Data from "4-6-2 Compound Superheater Express Locomotive, Paris, Lyons and Mediterranean Ry.", Locomotive Magazine, Volume XXII [22] (15 November 1916), pp. 219-220, 228-229 , (15 December 1916), pp 245-249. Ateliers et Chantiers de la Loire followed with the 6 021-6 050 and 6 251-6 260 in 1913-1914. SACM finished the class after World War One by producting 6 261-6 285 in 1919-1921..

Based on the 6001 (Locobase 13398), and essentially identical to the foreign-built 6201-6220s shown in Locobase 2535, this class had the same cylinder and heating surface dimensions, but working pressure lowered by 1 bar (14.5 psi). This was the production version of the superheated compound layout whose superiority was judged superior in all respects to the simple-expansion test engine.

The LP cylinders lay between the frames under the smokebox, slightly inclined (4 deg, 51 min) and driving the lead coupled axle; their piston valve diameters were 360 mm (14.17") each. Lying outside, but in line with the LP cylinders, the HP cylinders drove the second axle and had piston valves measuring 240 mm (9.45") in diameter. Dampers for the superheaters (for use while drifting to avoid over-heating the flues) had proved unnecessary, and thus the smokebox (impressively long at 3 metres (9.84 ft or 118") had few appliances other than a simple spark arrester.

Both the front and rear plates of the firebox reclined to the rear, clearing the coupled axles and relieving weight on the rear Bissel truck. While nominal pressure was set at 16 kg/sq cm (15.7 bar or 228 psi), the report said that the PLM was more likely set it 1 kg/sq cm lower. in practice.

(Note: See p. 247 of the report cited above for an impressive and thoroughly annotated diagram of the 6221's footplate.)