Boston & Maine class P-4
United States 1934 10 produced
The last ten Pacifics that the Boston & Maine purchased were also the last Pacifics that Lima manufactured. Their task was regional traffic over distances of up to around 200 miles, and they were designed for an average speed of 70 mph or 113 km/h. The firebox contained three thermic syphons and arch tubes. The coffin feed water heater was concealed in the smokebox. Initially there was a skyline casing on the top of the boiler, which was later removed. The locomotives from the two production years 1934 and 1937 were designated P-4a and P-4b. They were given names that were chosen in a competition among kindergarten children and students. Only 3713, which is currently being overhauled in Steamtown, has been preserved.
Technical data
General
- Built
- 1934, 1937
- Manufacturers
- Lima
- Wheel arrangement
- 4-6-2 (Pacific)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Wheelbase
- 11.25 m
- Total wheelbase
- 23.65 m
- Service mass
- 153.9 t
- Adhesion mass
- 95 t
- Total mass
- 263.1 t
- Rigid wheelbase
- 4.27 m
- Axle load
- 31.3 t
- Water capacity
- 45,425 l
- Fuel capacity
- 16.8 t (coal)
Boiler
- Grate area
- 6.215 m²
- Firebox surface
- 29.729 m²
- Tube heating surface
- 327.762 m²
- Evaporative heating surface
- 357.491 m²
- Superheater surface
- 89.744 m²
- Total heating surface
- 447.2 m²
Power plant
- Driver diameter
- 2,032 mm
- Boiler pressure
- 17.9 bar
- Expansion type
- simple expansion
- Cylinders
- two, 584 x 711 mm
Power
- Power source
- steam
- Estimated power
- 2,685 kW (3,651 PS)
- Starting effort
- 182.0 kN
Calculated values
- Factor of adhesion
- 1 : 5.12
- Optimal speed
- 90 km/h
- Power-to-weight ratio
- 17.5 kW/t
- Heating Surface Equivalent
- 685.6 m²
- Cylinder volume/HSE
- 1 : 556.09
- Adhesive weight/Total
- 1 : 1.62
- Tractive force/Heating surface
- 1 : 8.50
- Grate area/Heating surface
- 1 : 71.96
- Firebox/Tube surface
- 1 : 11.02
- Total/Superheater
- 1 : 3.98