Est Articulated Locomotives in France

Class Details by Steve Llanso of Sweat House Media

Class 6001 (Locobase 3614)

Wiener (1930) for data. Data from EncyclopTdie "Trains de lTgende" - Editions Atlas, as reproduced on the French locomotive website [], last accessed 16 November 2006; and "Mallet Articulated Compound Locomotives for the Eastern Railway of France", Railroad Age Gazette, Volume XLII [47], No 21 (19 November 1909), 969-971; and "Articulated Compound Locomotives, Eastern Ry. of France", Railway and Engineering Review, Volume 48 (12 December 1908), pp. 1006-1008. (Thanks to Alexander Blessing for his 1/1/2023 email noting the correct values for boiler pressure, driver wheelbase, and engine and tender wheelbase ) Works numbers were 45580-45581 in November 1908.

An interesting locomotive for several reasons. First, almost as soon as American builders were producing Mallets for domestic use they were exporting them. This design was one of the very few Mallet (or articulated of any sort) to enter service on a French railroad. Note the lack of a superheater and the relatively large heating areas available to even a small Mallet.

The Encyclopedie article notes that the the Est turned to an American for the Mallet because they needed more powerful help on a 2 1/4% grade that ascended from the floor of the Briey valley near Meurthe-et-Moselle. And the two Alcos proved up to the task, pulling 520 tons at 20-30 km/h (12-19 mph). The bar frames and smokebox were purely American and the French found the steam passages between the HP and LP cylinders to be a better solution than those used in France for such engines.

One adjustment was to place the lowest gauge cock to keep at least 60 mm (1 1/3") above the crown sheet when the engine climbed or descended the steepest grade. Another design change was designed to reduce the LP cylinder exhaust pipe deflections around tight curves. Acknowledging the exhaust's complex path from LP cylinder to common exhaust in the smokebox, RG noted that the steam passages were "cored out with large radii to counteract as far as possible the friction of the steam in passing through these tortuous passages."

But the boilers proved too small, being unable to maintain an adequate steam supply for a long period. As a result, their careers were over within 15 years, the 6001 being retired in 1922, the 6002 in 1928.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID3614
Number in Class2
Road Numbers6001-6002
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)18 / 5.49
Engine Wheelbase (ft / m)34.84 / 10.62
Ratio of driving wheelbase to overall engine wheelbase 0.52
Overall Wheelbase (engine & tender) (ft / m)41.83 / 12.75
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)182,000 / 82,554
Engine Weight (lbs / kg)205,632 / 93,273
Tender Loaded Weight (lbs / kg)115,024 / 52,174
Total Engine and Tender Weight (lbs / kg)320,656 / 145,447
Tender Water Capacity (gals / ML)2859 / 10.83
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 5.60 / 5.10
Minimum weight of rail (calculated) (lb/yd / kg/m)51 / 25.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)50 / 1270
Boiler Pressure (psi / kPa)214 / 14.80
High Pressure Cylinders (dia x stroke) (in / mm)17.52" x 25.98" / 445x660
Low Pressure Cylinders (dia x stroke) (in / mm)27.99" x 25.98" / 711x660
Tractive Effort (lbs / kg)41,689 / 18909.83
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.37
Heating Ability
Tubes (number - dia) (in / mm)269 - 1.929" / 49
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)18.01 / 5.49
Firebox Area (sq ft / m2)133.04 / 12.36
Grate Area (sq ft / m2)40.47 / 3.76
Evaporative Heating Surface (sq ft / m2)2547 / 236.62
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2547 / 236.62
Evaporative Heating Surface/Cylinder Volume351.35
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation8661
Same as above plus superheater percentage8661
Same as above but substitute firebox area for grate area28,471
Power L13096
Power MT225.02

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