Ferrovie dello Stato 4-6-0 Locomotives in Italy


Class Details by Steve Llanso of Sweat House Media

Class Gruppo 640 (Locobase 8960)

Data from Albert H Bone, "Some Recent Designs of Locomotives for Service on Continental Railways", Cassier's Magazine, 1910, pp. 561-609.

Bone notes that these were identical to the previous class of 2-cylinder, cross-compound Gruppo 630s locomotives save for the substitution of superheater flues and elements for the wholly saturated boilers of the earlier class of 62 engines. The Zara truck reduced the rigid wheelbase to 2.25 m (7 ft 4.6"). "In actual service," reported Bone,"these engines have shown a marked superiority over the compound engines of similar dimensions in coal and water consumption, especially with heavy trains." They were credited with a sustained output of 1,000 to 1,050 horsepower.


Class Gruppo 666 (Locobase 11407)

Data from "Locomotives for the Italian Government Railways," Railroad Gazette, Volume XLII [42], No 2 (11 January 1907), pp. 50-51; and DeGolyer, Volume 29, p. 125. Additional data from diagram published on DUEGI EDITRICE's TuttoTreno website [link], a modelling site with a great deal of data. (visited 11 July 2004); and "Postcards showing two Baldwin-designed and built steam locomotive classes", Posted byu/Historynerd88

September 2021 on Reddit's r/TrainPorn at [link], last accessed 13 March 2022. Works numbers were 28642 in July 1906; 28701, 28706, 28718-28719, 28763, 28804, 28827, 28833-28834 in August.

Baldwin built this set of balanced compound Ten-wheelers using metric measures, but othewise, according to the RG report, "...the general design of these locomotives follows American practice closely." One result was that these engines had the largest boilers of any Italian 4-6-0. The inside HP cylinders drove the front axle, while the outside LP cylinders drove the second and a single 15" (380-mm) piston valve supplied steam to each group of 1 LP and 1 HP cylinder on a side.

One significant difference in five of the class was the provision of a copper firebox in place of the steel furnaces found in most US locomotives by that time. Another difference, this time from most other four-cylinder compounds, was the provision of a shorter stroke of 610 mm for the inside HP cylinders vs the 660 mm for the outside LP. Still another was the more rudimentary shelter for the crew.

r/TrainPorn wrote that the class arrived in 1907 and was put to work on the Rome-Florence mainline, "but in the end the results were not good enough to justify further orders. " He added that while the Vauclain system "had its advantages ...it did not show a marked superiority to the Plancher engine." The experiment with steel fireboxes proved a failure, they "wore off awfully fast." He acknowledged that the problem "was partly down to issues with the German coal used, especially after WW I."

The Baldwins were gone by the end of the 1930s.

Principal Dimensions by Steve Llanso of Middle Run Media
ClassGruppo 640Gruppo 666
Locobase ID8960 11407
RailroadFerrovie dello Stato (FS)Ferrovie dello Stato (FS)
CountryItalyItaly
Whyte4-6-04-6-0
Number in Class16910
Road Numbers64001 a 641696661-6670
GaugeStdStd
Number Built16910
BuilderBerliner MaschinenbauBurnham, Williams & Co
Year19071906
Valve GearWalschaertStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.78 / 4.2013.45 / 4.10
Engine Wheelbase (ft / m)22.15 / 6.7526.74 / 8.15
Ratio of driving wheelbase to overall engine wheelbase 0.62 0.50
Overall Wheelbase (engine & tender) (ft / m)55.45 / 16.90
Axle Loading (Maximum Weight per Axle) (lbs / kg)34,170 / 16,000
Weight on Drivers (lbs / kg)97,665 / 44,30098,987 / 44,900
Engine Weight (lbs / kg)121,408 / 55,070146,001 / 66,225
Tender Loaded Weight (lbs / kg)73,855 / 33,500100,090 / 45,400
Total Engine and Tender Weight (lbs / kg)195,263 / 88,570246,091 / 111,625
Tender Water Capacity (gals / ML)3886 / 14.725280 / 20
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 5.50 / 5 6.60 / 6
Minimum weight of rail (calculated) (lb/yd / kg/m)54 / 2755 / 27.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)72.80 / 185072.80 / 1849
Boiler Pressure (psi / kPa)169.70 / 1170203.10 / 1400
High Pressure Cylinders (dia x stroke) (in / mm)21.26" x 27.56" / 540x70015.55" x 24.02" / 395x610
Low Pressure Cylinders (dia x stroke) (in / mm)25" x 25.98" / 635x660
Tractive Effort (lbs / kg)24,682 / 11195.5820,289 / 9202.95
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.96 4.88
Heating Ability
Tubes (number - dia) (in / mm)116 - 1.969" / 50250 - 2.008" / 51
Flues (number - dia) (in / mm)21 - 5.236" / 133
Flue/Tube length (ft / m)13.12 / 415.42 / 4.70
Firebox Area (sq ft / m2)106.52 / 9.90150.16 / 13.95
Grate Area (sq ft / m2)26.90 / 2.5033.37 / 3.10
Evaporative Heating Surface (sq ft / m2)1116 / 103.702169 / 201.51
Superheating Surface (sq ft / m2)361 / 33.55
Combined Heating Surface (sq ft / m2)1477 / 137.252169 / 201.51
Evaporative Heating Surface/Cylinder Volume98.56410.82
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation45656777
Same as above plus superheater percentage56616777
Same as above but substitute firebox area for grate area22,41530,497
Power L189064875
Power MT603.11325.73

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