Mediterraneo / FS 4-6-4 Locomotives in Italy


Class Details by Steve Llanso of Sweat House Media

Class Gruppo 690 / 950 (Locobase 9187)

Data from Maurice Demoulin, Locomotive Actuelle ... (Paris: Librairie Polytechnique Ch.Beranger, 1906), p. 269 and [link].

Locobase struggled to find any other information outside of Demoulin's account in his book and Demoulin does not provide the driver diameter. Fortunately, the Italian modeller's site does and gives us information about wheelbases and fuel loadings. The design used a Smith-type compounding system in which the single HP cylinder on the centerline fed 2 LP cylinders outside of nearly the same diameter. (See Locobase 2231 for a description of the Smith system.) The engines were rated at 480 hp and held to a maximum speed of 80 km/h (50 mph).

The Italian sources do not say, but both refer to the locomotives as simple-expansion locomotives with outside cylinders. Possibly the third cylinder was removed to simplify maintenance.

The class was assigned to the Turin area, serving the Pinerolo - Torre Pellice line.

Principal Dimensions by Steve Llanso of Middle Run Media
ClassGruppo 690 / 950
Locobase ID9187
RailroadMediterraneo / FS
CountryItaly
Whyte4-6-4T
Number in Class6
Road Numbers6901-6906 / 9501-9506
GaugeStd
Number Built6
BuilderHartmann
Year1905
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)10.63 / 3.24
Engine Wheelbase (ft / m)31.17 / 9.50
Ratio of driving wheelbase to overall engine wheelbase 0.34
Overall Wheelbase (engine & tender) (ft / m)31.17 / 9.50
Axle Loading (Maximum Weight per Axle) (lbs / kg)29,762 / 13,500
Weight on Drivers (lbs / kg)89,287 / 40,500
Engine Weight (lbs / kg)164,244 / 74,500
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)1584 / 6
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 3.30 / 3
Minimum weight of rail (calculated) (lb/yd / kg/m)50 / 25
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)59.10 / 1500
Boiler Pressure (psi / kPa)213.20 / 1470
High Pressure Cylinders (dia x stroke) (in / mm)16.93" x 25.2" / 430x640 (1)
Low Pressure Cylinders (dia x stroke) (in / mm)17.32" x 25.2" / 440x640
Tractive Effort (lbs / kg)16,989 / 7706.09
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.26
Heating Ability
Tubes (number - dia) (in / mm)
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)
Firebox Area (sq ft / m2)
Grate Area (sq ft / m2)19.37 / 1.80
Evaporative Heating Surface (sq ft / m2)1054 / 98
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1054 / 98
Evaporative Heating Surface/Cylinder Volume321.06
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation4130
Same as above plus superheater percentage4130
Same as above but substitute firebox area for grate area
Power L1
Power MT

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