This one-of-a-kind was the Bay.St.B's first Mallet. Its relatively tall drivers reduced its tractive effort and the engine rode badly as well. Only occasionally used, the 2500 was donated to the Nuremburg museum in 1924, where its boiler was cut away to show the internal layout. The DRG's classification system extended to this engine -- 55.7101 -- but it never actually operated in DR service.
See [] for data and comment.
Data from [] (accessed 27 December 2002; US Military Railway Service Equipment Data Book for German Locomotives supplied by Allen Stanley from his extensive Rail Data Exchange collection in March 2004; and Albert Gieseler, "Baureihe 98 701-729" on the Dampfmaschinen und Lokomotiven website at [
], last accessed 12 February 2022.
Obviously learning from the failure of the large BB I Mallet that had represented Bay.St.B's first venture into articulation, this later design was much smaller and less ambitious.
Maffei delivered the first batch (works numbers 2003-2005) in 1899.
Later batches arrived as follows:
Year Works numbers
1900 2077-2084
1901 2177-2190
1903 2290-2293
1908 3023-3024
Their performance was adequate, said the malletlok site, although the BB IIs required considerable maintenance and had high operating costs. Despite this, however, the DRG took all 31 into its national system in 1925.
Most were retired in 1932-1938; some of them were purchased by private industry. 98.727, for example, became South German Sugars AG #4 and was held in readiness for service for decades.
Data from Gustav Reder (Michael Reynolds, trans), The world of steam locomotives (New York: Putnam, 1974), pl. 331. See also K H Miska ([]); and "The Largest Locomotive in Europe," Railway Magazine, Volume 34, p. 332; "The Heaviest and Most Powerful Tank Locomotive in Europe", Locomotive Magazine, Volume XX [20], No 258 (14 February 1914), pp. 45-46; and "Baureihe 96 001-015 " entry at Albert Gielseler's 8
[], last accessed 23 October 2017.
These Mallet compound articulated locomotives were designed to a tonnage requirement of 670 tons up a 2% grade, 540 tons up 2.5%. Interestingly, despite the small drivers, these engines also had to hit 31 mph (50 kph) while pulling expresses. K H Miska reports that these brutes were intended for three locations. the Schiefe Egene between Neuenmarkt and Marktschorgast (4.21 miles/6.8 km at a 2 1/2% grade), Spessartrampe between Laufach and Heigenbrucken (3.22 miles/5.2 km at 2%), and Frankenwaldbahn between Rothenkirchen and Probstzella (15.9 miles at a ruling grade of 2 1/2%).
After 15 were delivered in 1913, Maffei added 10 more in 1923; see Locobase 3635.
Reder observes that the low-pressure cylinders were starved for steam when at full throttle. A later rebuild that improved drafting while increasing the HP cylinder diameter to 23.63" and superheater area proved effective, but its cost confined the rebuild to twelve engines. (See 3635 for further details.) These later became the Deutsche Bahn Class 96. Their service lasted only until the end of World War II, being sidelined by 1947 in West Germany, 1949 in the East.
Wiener (1930) for additional data.
Data from Lionel Wiener, Articulated Locomotives (orig published, 1930, reprinted Milwaukee: Kalmbach Publishing Company, 1970) and Gustav Reder (Michael Reynolds, trans), The world of steam locomotives (New York: Putnam, 1974), pl 331. See also KH Miska []; and "Baureihe 96 016-025 " in Albert Gieseler's Dampmachinen und Lokomotiven website at at [
], last accessed 8 December 2019. Works numbers were 5769-5775 in 1922.
These are a second order of Consolidated Mallet tanks with slightly longer tubes and hence more surface area.
Wiener reported that these were not satisfactory when they were introduced, the tractive effort being no greater than the T-20 tanks that were 30 metric tons lighter. Several deficiencies were noted, one relating to adhesion distribution: As these were helper engines on steep grades, more than the half of the adhesion weight would be thrown back on the HP cylinder set. When this happened, the LP cylinder set would start slipping. Then, Wiener says, "[t]he pressure in the intermediate receiver pipe would drop and this slipping would cease; but, as a corollary, the HP cylinders would develop too high a tractive force and the back set of wheels would start slipping in their turn."
In addition, Reder (1974, pl 331) observes that the low-pressure cylinders were starved for steam when at full throttle. And K H Miska reports that the Mallet had a sideways oscillation around the frame pivot point that was traced back to the difference between high and low pressure cylinder volumes.
The 1925 rebuild improved drafting while increasing the HP cylinder diameter to 23.63" and superheater area; it also corrected the oscillation problem as well. It proved effective, but its cost confined the rebuild to 12 engines. These later became the Deutsche Bahn Class 96.
Wiener (1930) for additional data.
Principal Dimensions by Steve Llanso of Middle Run Media | ||||
---|---|---|---|---|
Class | BB I/BR 55 7101 | BB II / BR 98.7 | Class Gt 2 x 4/4//BR 96.001 | Class Gt 2 x 4/4//BR 96.016 |
Locobase ID | 5064 | 5065 | 2755 | 3635 |
Railroad | Bavarian State | Bavarian State | Bavarian State | Bavarian State |
Country | Germany | Germany | Germany | Germany |
Whyte | 0-4-4-0 | 0-4-4-0T | 0-8-8-0T | 0-8-8-0T |
Number in Class | 1 | 31 | 15 | 10 |
Road Numbers | 2100 | 2501-2531 | 96001-96015 | 96016-25 |
Gauge | Std | Std | Std | Std |
Number Built | 1 | 31 | 15 | 10 |
Builder | Maffei | Maffei | Maffei | Maffei |
Year | 1896 | 1899 | 1913 | 1923 |
Valve Gear | Heusinger | Heusinger | Walschaert | Walschaert |
Locomotive Length and Weight | ||||
Driver Wheelbase (ft / m) | 5.68 / 1.73 | 5.25 / 1.60 | 14.76 / 4.50 | 29.53 / 9 |
Engine Wheelbase (ft / m) | 19.37 / 5.91 | 17.06 / 5.20 | 40.03 / 12.20 | 40.03 / 12.20 |
Ratio of driving wheelbase to overall engine wheelbase | 0.29 | 0.31 | 0.37 | 0.74 |
Overall Wheelbase (engine & tender) (ft / m) | 57.51 / 17.53 | 57.51 / 17.53 | ||
Axle Loading (Maximum Weight per Axle) (lbs / kg) | 31,306 / 14,200 | 23,479 / 10,650 | 33,951 / 15,400 | 36,156 / 16,400 |
Weight on Drivers (lbs / kg) | 123,856 / 56,180 | 93,917 / 42,600 | 271,609 / 123,200 | 289,026 / 131,100 |
Engine Weight (lbs / kg) | 123,856 / 56,180 | 93,917 / 42,600 | 271,655 / 123,221 | 289,026 / 131,100 |
Tender Loaded Weight (lbs / kg) | ||||
Total Engine and Tender Weight (lbs / kg) | ||||
Tender Water Capacity (gals / ML) | 1135 / 4.30 | 2904 / 11 | 2701 / 10.23 | |
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 2.20 / 2 | 5 / 5 | 5 / 5 | |
Minimum weight of rail (calculated) (lb/yd / kg/m) | 52 / 26 | 39 / 19.50 | 57 / 28.50 | 60 / 30 |
Geometry Relating to Tractive Effort | ||||
Driver Diameter (in / mm) | 52.40 / 1330 | 39.60 / 1006 | 47.90 / 1217 | 48 / 1220 |
Boiler Pressure (psi / kPa) | 203.10 / 1400 | 174 / 1200 | 217.60 / 1500 | 217.60 / 1500 |
High Pressure Cylinders (dia x stroke) (in / mm) | 16.34" x 24.8" / 415x630 | 12.2" x 20.87" / 310x530 | 20.47" x 25.2" / 520x640 | 20.47" x 25.2" / 520x640 |
Low Pressure Cylinders (dia x stroke) (in / mm) | 25" x 24.8" / 635x630 | 19.29" x 20.87" / 490x530 | 31.5" x 25.2" / 800x640 | 31.5" x 25.2" / 800x640 |
Tractive Effort (lbs / kg) | 30,570 / 13866.34 | 16,574 / 7517.85 | 57,335 / 26006.75 | 57,215 / 25952.32 |
Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.05 | 5.67 | 4.74 | 5.05 |
Heating Ability | ||||
Tubes (number - dia) (in / mm) | 192 - 2.008" / 51 | 138 - 1.772" / 45 | 213 - 2.087" / 53 | 247 - 2.087" / 53 |
Flues (number - dia) (in / mm) | 24 - 5.315" / 135 | 34 - 5.63" / 143 | ||
Flue/Tube length (ft / m) | 13.39 / 4.08 | 11.81 / 3.60 | 16.67 / 5.08 | 16.67 / 5.08 |
Firebox Area (sq ft / m2) | 96.84 / 9 | 58.13 / 5.40 | 158.77 / 14.75 | 157.69 / 14.65 |
Grate Area (sq ft / m2) | 22.27 / 2.07 | 15.07 / 1.40 | 46.29 / 4.30 | 46.29 / 4.30 |
Evaporative Heating Surface (sq ft / m2) | 1320 / 122.68 | 728 / 67.66 | 2485 / 230.89 | 2157 / 200.43 |
Superheating Surface (sq ft / m2) | 596 / 55.39 | 704 / 65.37 | ||
Combined Heating Surface (sq ft / m2) | 1320 / 122.68 | 728 / 67.66 | 3081 / 286.28 | 2861 / 265.80 |
Evaporative Heating Surface/Cylinder Volume | 219.30 | 257.82 | 258.89 | 224.72 |
Computations Relating to Power Output (More Information) | ||||
Robert LeMassena's Power Computation | 4523 | 2622 | 10,073 | 10,073 |
Same as above plus superheater percentage | 4523 | 2622 | 11,987 | 12,591 |
Same as above but substitute firebox area for grate area | 19,668 | 10,115 | 41,113 | 42,892 |
Power L1 | 2271 | 1657 | 6605 | 7108 |
Power MT | 161.69 | 155.59 | 428.90 | 433.74 |