Baltimore & Ohio class O “Old Maude”
class DD1
United States 1904 1 produced
The name “Old Maude” refers to a mule in a comic, but also the first large Mallet in the USA built for standard gauge. Its job was as a helper for heavy trains on inclines, what didn't require high speeds. This meant that she did not require any carrying axles, meaning that all six axles were available for traction. The top speed of 21 mph or 34 km/h was completely sufficient for her tasks. Although the locomotive, which was initially designated class O and later renamed DD1, did not have any sisters, it remained in service until 1938.
Technical data
General
- Built
- 1904
- Manufacturers
- ALCO
- Wheel arrangement
- 0-6-6-0 (Erie)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Wheelbase
- 9.35 m
- Service mass
- 151.8 t
- Adhesion mass
- 151.8 t
- Rigid wheelbase
- 3.05 m
- Axle load
- 216.6 t
- Water capacity
- 26,498 l
- Fuel capacity
- 11.8 t (coal)
Boiler
- Grate area
- 6.708 m²
- Firebox surface
- 20.383 m²
- Tube heating surface
- 498.574 m²
- Evaporative heating surface
- 518.957 m²
- Total heating surface
- 519.0 m²
Power plant
- Driver diameter
- 1,422 mm
- Boiler pressure
- 16.2 bar
- Expansion type
- compound
- Cylinders
- four, HP: 508 x 813 mm and LP: 813 x 813 mm
Power
- Power source
- steam
- Estimated power
- 1,491 kW (2,027 PS)
- Top speed
- 34 km/h
- Starting effort
- 292.1 kN
- Starting effort simple
- 350.5 kN
Calculated values
- Factor of adhesion
- 1 : 5.10
- Optimal speed
- 31 km/h
- Power-to-weight ratio
- 9.8 kW/t
- Heating Surface Equivalent
- 620.9 m²
- Cylinder volume/HSE
- 1 : 1,209.94
- Adhesive weight/Total
- 1 : 1.00
- Tractive force/Heating surface
- 1 : 11.76
- Grate area/Heating surface
- 1 : 77.36
- Firebox/Tube surface
- 1 : 24.46
