Assam Bengal Beyer-Garratt Locomotives in India
Class Details by Steve Llanso of Sweat House Media
Class T (Locobase 685)
Data from Wiener (1930) and from "Assam Bengal Railway-Design 1127", Beyer-Garrrat Patent Articulated Locomotives (Manchester, England: Beyer-Peacock & Company Limited, 1931), archived on flickr's Historical Railway Images at [
], et seq, p. 28. Works numbers were 6385-6389 in 1931.
Prairie Garratts bought to work mixed-traffic trains over The Hill over ruling gradients of 1 in 60 (1.67%) and an 11-mile (17.7-km) section between Harangaja and Jatinga up 1 in 37 (2.7%). Described by BP as "a conspicuous example of perseverance and engineering skill overcoming almost insuperable difficulties, the 115 1/4 (185.6 km) miles required 37 tunnels and "numerous bridges" and curves as tight as 382 ft.
Acknowledging that such obstacles required all trains, including those headed by a Garratt, to use "banking" engines, BP was nonetheless able to claim that the average Garratt trainload measured 300 tons or 30% more than "the most powerful EIGHT-coupled locomotives." Moreover, the Garratt's lower axle load and greater flexibility, they claimed, had "added materially to the safe working of this section."
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | T |
| Locobase ID | 685 |
| Railroad | Assam Bengal |
| Country | India |
| Whyte | 2-6-2+2-6-2 |
| Number in Class | 5 |
| Road Numbers | 401-405 |
| Gauge | Metre |
| Number Built | 5 |
| Builder | Beyer, Peacock |
| Year | 1927 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 17.83 / 5.43 |
| Engine Wheelbase (ft / m) | 38.67 / 11.79 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.46 |
| Overall Wheelbase (engine & tender) (ft / m) | 59 / 17.98 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 21,280 / 9652 |
| Weight on Drivers (lbs / kg) | 127,680 / 57,915 |
| Engine Weight (lbs / kg) | 202,048 / 91,648 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 2400 / 9.09 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 6.70 / 6.10 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 35 / 17.50 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 48 / 1219 |
| Boiler Pressure (psi / kPa) | 180 / 1240 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 14" x 24" / 356x610 (4) |
| Tractive Effort (lbs / kg) | 29,988 / 13602.34 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.26 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | 186 - 1.75" / 44 |
| Flues (number - dia) (in / mm) | 26 - 5.25" / 133 |
| Flue/Tube length (ft / m) | |
| Firebox Area (sq ft / m2) | 132 / 12.26 |
| Grate Area (sq ft / m2) | 30 / 2.79 |
| Evaporative Heating Surface (sq ft / m2) | 1430 / 132.85 |
| Superheating Surface (sq ft / m2) | 268 / 24.90 |
| Combined Heating Surface (sq ft / m2) | 1698 / 157.75 |
| Evaporative Heating Surface/Cylinder Volume | 167.21 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 5400 |
| Same as above plus superheater percentage | 6264 |
| Same as above but substitute firebox area for grate area | 27,562 |
| Power L1 | 7580 |
| Power MT | 785.29 |