Decauville RR at Paris Exposition Articulated Locomotives in France

Class Details by Steve Llanso of Sweat House Media

Class l'Avenir (Locobase 11383)

Data from M. A Mallet, " The Development of the Compound System in Locomotives," The Railroad and Engineering Journal, Vol LXV, No 5 (May 1891), pp. 202-204.

This little Mallet worked on the railway system set up to convey passengers around the grounds of the 1889 Paris Exposition. Like Eiffel's Tower, which was erected for the same fair, l' Avenir exerted an enduring influence. It was one of the very first to use the four-cylinder compounding system that would dominate articulated-locomotive operation for decades.

The locomotive was rated at 260 tons, pulling bogie passenger cars over a 3 km (1.9 mile) track on the grounds at a maximum 16 kph (10 mph) and 3.2 kph (2 mph) through the level (grade) crossings. Rails weighed 19 lb/yard (9.5 kg/metre) and were laid in 7.75 metre (25 ft 5 in) sections.

At least three of the articulated locomotives operating on the Chemins de fer du Calvados in Normandy had begun their careers on the Exposition Railway in 1889. Calvados numbers 1,m 2, and 6 (Cabourg, Salenelles, and Varaville, respectively) had been sold to the Tramways de Royan in 1891.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID11383
RailroadDecauville RR at Paris Exposition
Number in Class8
Road Numbers
Gauge60 cm
Number Built8
Valve Gearvarious
Locomotive Length and Weight
Driver Wheelbase (ft / m) 5.58 / 1.70
Engine Wheelbase (ft / m) 9.19 / 2.80
Ratio of driving wheelbase to overall engine wheelbase 0.61
Overall Wheelbase (engine & tender) (ft / m) 9.19 / 2.80
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)25,794 / 11,700
Engine Weight (lbs / kg)25,794 / 11,700
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)25,794 / 11,700
Tender Water Capacity (gals / ML)370 / 1.40
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)11 / 5.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)23.60 / 600
Boiler Pressure (psi / kPa)169.70 / 11.70
High Pressure Cylinders (dia x stroke) (in / mm)7.48" x 10.24" / 190x260
Low Pressure Cylinders (dia x stroke) (in / mm)11.02" x 10.24" / 280x260
Tractive Effort (lbs / kg)4795 / 2174.98
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.38
Heating Ability
Tubes (number - dia) (in / mm)
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)
Firebox Area (sq ft / m2)24.76 / 2.30
Grate Area (sq ft / m2) 5.38 / 0.50
Evaporative Heating Surface (sq ft / m2)240 / 22.30
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)240 / 22.30
Evaporative Heating Surface/Cylinder Volume460.82
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation913
Same as above plus superheater percentage913
Same as above but substitute firebox area for grate area4202
Power L12148
Power MT734.36

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