Paris-Lyon-Mediterrannee 4-8-4 Locomotives in France


Class Details by Steve Llanso of Sweat House Media

Class 242.AT / 242 TA (Locobase 2133)

Data from US Military Railway Service Equipment Data Book for French Locomotives supplied by Allen Stanley in March 2004 from his extensive Rail Data Exchange, supplemented by B Bathiat, "Les 242 Tendre aux PLM et AL", Rail Magazine, No 22 (January 1979), pp. 18-24, archived at Les Trains de l'Histoire, [], last accessed 2 November 2011. See also Robert Tufnell, The Illustrated Encyclopedia of Railway Locomotives (London: Quarto Publishing Ltd, 1986). Builders included Batignolles Chatillon, Creusot, Schneider, and SACM.

Deliveries of the 4-8-4T continued until 1933 in several batches with some modifications. These long-boilered engines with their loaf-of-bread domes worked fast suburban service from the Gare de Lyon in Paris and were credited with speeds of up to 95 km/h (59 mph).

Twelve more smooth firetubes measured 2.16".

All had Belpaire fireboxes and a steeply sloping grate inserted between the 3rd and 4th driving axles and increasing the spacing 16" compared to the spread of the first 3 axles. The HP cylinders drove the second axle and were served by 240-mm (9.45-inch) valves. The LP cylinders turned the first axle and had 310-mm (12.2-inch) valves.

One defect in all of the series was that they suffered from a "weakness of constitution" ("faiblesse de constitution") in the construction of their frames, which were too small for the long wheelbase. This problem had to be fixed several times during their long careers.


Class 242.BT / 242 TB (Locobase 13348)

Data from B Bathiat, "Les 242 Tendre aux PLM et AL", Rail Magazine, No 22 (January 1979), pp. 18-24, archived at Les Trains de l'Histoire, [], last accessed 2 November 2011. See also the PLM Wiki at [], last accessed 4 November 2011.

Locobase 2133 gives details of the original class of 242.ATs delivered in 1926. This second version was produced by Batignolles (1-5) and Schneider (6-30). Like the ATs, the BTs had Belpaire fireboxes and a steeply sloping grate inserted between the 3rd and 4th driving axles and increasing the spacing 16" (406 mm) compared to the spread of the first 3 axles. Also like the ATs, the BTs had 12 more smooth firetubes that measured 55 mm (2.16") in external diameter.

The HP cylinders drove the second axle and were served by 240-mm (9.45-inch) valves. The LP cylinders turned the first axle and had 310-mm (12.2-inch) valves.

Bathiat notes that although they were no more powerful than the ATs, BTs were nevertheless remarkable for their more energetic departures and their tractive power. Perhaps the use of an oscillating-cam valve gear made the difference.


Class 242.CT / 242 TC (Locobase 13349)

Data from US Military Railway Service Equipment Data Book for French Locomotives supplied by Allen Stanley in March 2004 from his extensive Rail Data Exchange, supplemented by B Bathiat, "Les 242 Tendre aux PLM et AL", Rail Magazine, No 22 (January 1979), pp. 18-24, archived at Les Trains de l'Histoire, [], last accessed 2 November 2011. See also [], last accessed 4 November

Combining the oscillating-cam valve gear of the BTs (Locobase 13348) and reducing the driver diameter by 150 mm, the CTs were especially designed for suburban routes that had challenging grades.They also had driving wheelbases that were 15 inches (380 mm) shorter and engine wheelbases just about 3 feet (900 mm) less .

Like the earlier types, however, the CTs had Belpaire fireboxes and a steeply sloping grate inserted between the third and fourth driving axles and increasing the spacing 16" (406 mm) compared to the spread of the first three axles. The HP cylinders drove the second axle and were served by 240-mm (9.45") valves. The LP cylinders turned the first axle and had 310-mm (12.2") valves. And the CTs also had twelve more smooth firetubes in the boiler that measured 55 mm (2.16") in external diameter.


Class 242.DT / 242 TD (Locobase 13350)

Data from US Military Railway Service Equipment Data Book for French Locomotives supplied by Allen Stanley in March 2004 from his extensive Rail Data Exchange, supplemented by B Bathiat, "Les 242 Tendre aux PLM et AL", Rail Magazine, No 22 (January 1979), pp. 18-24, archived at Les Trains de l'Histoire, [], last accessed 2 November 2011. See also the PLM Wiki at [], last accessed 4 November 2011.

The CTs shown in Locobase 13349 conferred the necessary tractive effort to negotiate the steeper portions of the PLM's commuter-rail network. So the railway returned to Batignolles a year later for another set of 50 locomotives. Like all of the 242T series, these had Belpaire fireboxes and like the BT and CT, the DTs had the oscillating-cam valve gear. And the DTs also had twelve more smooth firetubes in the boiler that measured 55 mm (2.16") in external diameter.The principal change was in weight; the DTs were a bit lighter.

Principal Dimensions by Steve Llanso of Sweat House Media

Class242.AT / 242 TA242.BT / 242 TB242.CT / 242 TC242.DT / 242 TD
Locobase ID2133 13348 13349 13350
RailroadParis-Lyon-Mediterrannee (PLM)Paris-Lyon-Mediterrannee (PLM)Paris-Lyon-Mediterrannee (PLM)Paris-Lyon-Mediterrannee (PLM)
CountryFranceFranceFranceFrance
Whyte4-8-4T4-8-4T4-8-4T4-8-4T
Number in Class120315050
Road NumbersAT.001-AT.120BT.001-BT.031TC.001-TC.050TD.001-TD.050
GaugeStdStdStdStd
Number Built120315050
BuilderseveralseveralBatignollesBatignolles
Year1926192919301931
Valve GearWalschaertLentz poppetLentz poppetLentz poppet
Locomotive Length and Weight
Driver Wheelbase (ft / m)19.39 / 5.9019.36 / 5.9018.24 / 5.5618.24 / 5.56
Engine Wheelbase (ft / m)47.08 / 14.3547.11 / 14.3643.96 / 13.4043.96 / 13.40
Ratio of driving wheelbase to overall engine wheelbase 0.41 0.41 0.41 0.41
Overall Wheelbase (engine & tender) (ft / m)47.08 / 14.3547.11 / 14.3643.96 / 13.4043.96 / 13.40
Axle Loading (Maximum Weight per Axle) (lbs / kg)35,274 / 16,00035,274 / 16,00035,274 / 16,000
Weight on Drivers (lbs / kg)143,325 / 65,011141,096 / 64,000141,096 / 64,000141,096 / 64,000
Engine Weight (lbs / kg)264,601 / 120,021257,544 / 116,820258,602 / 117,300257,544 / 116,820
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)264,601 / 120,021257,544 / 116,820258,602 / 117,300257,544 / 116,820
Tender Water Capacity (gals / ML)3168 / 123168 / 123168 / 12
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 5.50 / 5 5.50 / 5 5.50 / 5
Minimum weight of rail (calculated) (lb/yd / kg/m)60 / 3059 / 29.5059 / 29.5059 / 29.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)64.70 / 164365 / 165059.10 / 150059.10 / 1500
Boiler Pressure (psi / kPa)232.10 / 16227.70 / 15.70227.70 / 15.70232.10 / 16
High Pressure Cylinders (dia x stroke) (in / mm)16.54" x 25.59" / 420x65016.54" x 25.59" / 420x65016.54" x 25.59" / 420x65016.54" x 25.59" / 420x650
Low Pressure Cylinders (dia x stroke) (in / mm)24.8" x 25.59" / 630x65024.8" x 25.59" / 630x65024.8" x 25.59" / 630x65024.8" x 25.59" / 630x650
Tractive Effort (lbs / kg)29,550 / 13403.6728,856 / 13088.8831,736 / 14395.2232,350 / 14673.73
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.85 4.89 4.45 4.36
Heating Ability
Tubes (number - dia) (in / mm)62 - 2.756" / 7062 - 2.756" / 7062 - 2.756" / 7062 - 2.756" / 70
Flues (number - dia) (in / mm)21 - 5.63" / 14321 - 5.63" / 14321 - 5.63" / 14321 - 5.63" / 143
Flue/Tube length (ft / m)16.40 / 516.40 / 516.40 / 516.40 / 5
Firebox Area (sq ft / m2)173.95 / 16.16174.16 / 16.18174.38 / 16.20174.38 / 16.20
Grate Area (sq ft / m2)33.15 / 3.0833.15 / 3.0833.15 / 3.0833.15 / 3.08
Evaporative Heating Surface (sq ft / m2)1867 / 173.451861 / 172.921865 / 173.221865 / 173.22
Superheating Surface (sq ft / m2)485 / 45.10489 / 45.47489 / 45.47489 / 45.47
Combined Heating Surface (sq ft / m2)2352 / 218.552350 / 218.392354 / 218.692354 / 218.69
Evaporative Heating Surface/Cylinder Volume293.38292.43293.06293.06
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation7694754875487694
Same as above plus superheater percentage9310913391339310
Same as above but substitute firebox area for grate area48,85247,98448,04548,973
Power L112,42312,29811,19011,406
Power MT764.36768.62699.37712.87

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