Mogiana 2-6-6-2 Locomotives in Brazil

Class Details by Steve Llanso of Sweat House Media

Class 150 (Locobase 3608)

Data from Wiener (1930). See also DeGolyer, Volume 36, pp. 309+. Works numbers were 35783-35784 in December 1910 and 37436-37437 in January 1912.

Used on 250-km (155 mile) line with 3% gradients. This outside- bar frame, wood-burning quartet of Mallets had the same power dimensions as Baldwins delivered to the Sorocabana Railways as their 40-43 in 1909-1910 (see Locobase 12930). That wasn't accidental as both Mogyana and Sorocabana were subsidiaries of the Brazil Railway Company. They had a classic North American profile with a long "cow catcher" pilot. One small difference between the two pairs: the headlight was relocated from a bracket just above the level of the cylinders to a mount at the top of the smokebox.

The Baldwin specs included a 9 May 1910 note from Baldwin's Brazil representative R K Johnson that the smokebox netting's mesh size had been changed from 10 x 10 to 7 x 7, a finer weave more suitable to catch the sparks thrown by the woodl used by the Mogyana. He also called for the fire deck to covered with wood to put the bottom of the fire door 25 1/2" (648 mm) above the deck.

A "Hereafter" note written exactly a year later and after the first two had entered service added that the outside radial valve motion was not to be supported from the guide bars. Locobase supposes that such support by a component that was itself subject to lateral and even vertical strains increased the chance that the motion would work itself out of alignment. In addition, Johnson said that the motion's radius rod struck the valve rod guide; "see that all parts of valve motion clear hereafter", he suggested.

A separate recommendation in the May 1911 note, the Baldwin rep recommended that projecting lugs on the front end of the rear engine be trimmed to avoid striking the rear of the front engine when one or both were on a curve.

The only two readily visible changes apparent in a 1936 photograph were a handle on the smokebox door and a taller, capped stack.

Class 754 (Locobase 3609)

Data from Wiener 1930 and "New Meter Gage [sic] Locomotives for South America", Railway Age, Volume 69 , No 20 (12 November 1920), pp. 839-841. Works numbers were 58790-58793 in 1919.

Henschel also supplied examples of this wood-burning Mallet design, according to Durrant (The Mallet Locomotive) reproduced on (See photo of this Alco-built engine at the same website.) In keeping with the European-oriented design practices of this railway, both the back tube sheet and firebox were made of copper. (Crown and side sheets were made of steel.) The rear engine's HP cylinders were supplied steam through piston valves while the LP cylinders ahead of the smokebox used slide valves.

RA noted that this quartet were "unusually heavy for narrow-gage [sic] service. "An interesting detail", said RA about the specifications called for "polished hand rails and a running board with polished edges." Appearance on South American railroads, they added, was an important factor, so "great pride" was taken to keep "all locomotive fixtures, particularly the apparatus in the cab, in a state of spotless perfection."

The tender carried a relatively heavy load of 4 cords of wood in addition to its water supply.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID3608 3609
Number in Class44
Road Numbers150-151, 162-163/750-753/950-953754-757/954-957
Number Built44
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)10 / 3.05 8.33 / 2.54
Engine Wheelbase (ft / m)42.75 / 13.0339.17 / 11.94
Ratio of driving wheelbase to overall engine wheelbase 0.23 0.21
Overall Wheelbase (engine & tender) (ft / m)66.33 / 20.2263.25 / 19.28
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)161,100 / 73,074156,000 / 70,760
Engine Weight (lbs / kg)189,800 / 86,092185,000 / 83,915
Tender Loaded Weight (lbs / kg)90,200 / 40,91493,900 / 42,592
Total Engine and Tender Weight (lbs / kg)280,000 / 127,006278,900 / 126,507
Tender Water Capacity (gals / ML)4500 / 17.054000 / 15.15
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)45 / 22.5043 / 21.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)47 / 119447 / 1194
Boiler Pressure (psi / kPa)204.50 / 14.10204.50 / 14.10
High Pressure Cylinders (dia x stroke) (in / mm)17" x 22" / 432x56016.5" x 24" / 419x610
Low Pressure Cylinders (dia x stroke) (in / mm)26.5" x 22" / 673x55926.5" x 24" / 673x610
Tractive Effort (lbs / kg)33,318 / 15112.8134,828 / 15797.73
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.84 4.48
Heating Ability
Tubes (number - dia) (in / mm)194 - 2.25" / 57104 - 2.25" / 57
Flues (number - dia) (in / mm)21 - 5.375" / 137
Flue/Tube length (ft / m)21 / 6.4020 / 6.10
Firebox Area (sq ft / m2)142 / 13.20131 / 12.17
Grate Area (sq ft / m2)41.60 / 3.8736.90 / 3.43
Evaporative Heating Surface (sq ft / m2)2528 / 234.941934 / 179.67
Superheating Surface (sq ft / m2)506 / 47.01
Combined Heating Surface (sq ft / m2)2528 / 234.942440 / 226.68
Evaporative Heating Surface/Cylinder Volume437.40325.61
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation85077546
Same as above plus superheater percentage85079131
Same as above but substitute firebox area for grate area29,03932,415
Power L136937469
Power MT303.23633.32

All material Copyright ©
Wes Barris