Pennsylvania Railroad class D7

Class D7 (formerly Class A (anthracite), pre-1895) on the Pennsylvania Railroad was a class of 4-4-0 steam locomotive.[4] Fifty-eight were built by the PRR's Altoona Works (now owned by Norfolk Southern) between 1882–1891 with 68 in (1.73 m) drivers, while sixty-one of class D7a were constructed with 62 in (1.57 m) drivers.[1]

Pennsylvania Railroad D7
PRR D7a #953 in its builders' portrait
Type and origin
Power typeSteam
BuilderPRR Altoona Works[1]
Build date1882–1891[1]
Total produced58 D7, 61 D7a[1]
Specifications
Configuration:
  Whyte4-4-0
  UIC2′B
Gauge4 ft 8+12 in (1,435 mm)
Leading dia.30 in (762 mm) (D7)[2]
33 in (838 mm) (D7a)[3]
Driver dia.68 in (1,727 mm) (D7)[2]
62 in (1,575 mm) (D7a)[3]
Wheelbase22 ft 7+12 in (6.90 m)[2][3]
Length58 ft 0.6 in (17.69 m)[3]
Height14 ft 4 in (4.37 m)[3]
Axle load32,650 lb (14.8 tonnes)[3]
Adhesive weight56,700 lb (25.7 tonnes) (D7) [2]
58,700 lb (26.6 tonnes)[3]
Loco weight93,500 lb (42.4 tonnes) (D7)[2]
96,330 lb (43.7 tonnes) (D7a)[3]
Total weight160,880 lb (73.0 tonnes)[3]
Fuel typeAnthracite coal[1]
Fuel capacity12,000 lb (5.4 tonnes)[3]
Water cap.2,400 US gal (9,100 L; 2,000 imp gal)[3]
Firebox:
  Firegrate area
34.75 sq ft (3.23 m2)[3]
Boiler pressure140 lbf/in2 (970 kPa)[3]
Heating surface1,289 sq ft (119.75 m2)[3]
  Tubes1,134 sq ft (105.35 m2)[3]
  Firebox155 sq ft (14.40 m2)[3]
Cylinders2[3]
Cylinder size17 in × 24 in (432 mm × 610 mm)[3]
Valve gearStephenson
Valve typeSlide valves
Performance figures
Tractive effort12,138 lbf (53.99 kN) (D7)
13,313 lbf (59.22 kN) (D6a)
Factor of adh.4.7 (D7) 4.4 (D7a)

The D7 was fundamentally an anthracite-burning version of the PRR D6, with a larger fire-grate in order to burn the slower-burning, harder coal.[5]

References

  1. "PRR Steam Roster". Northeast Rails. Retrieved 2007-12-31.
  2. Pennsylvania Railroad. "D7 Diagram". PRR.Railfan.net. Retrieved 2008-08-17.
  3. Pennsylvania Railroad. "D7a Diagram". PRR.Railfan.net. Retrieved 2008-08-17.
  4. Staufer, Alvin F. & Pennypacker, Bert (1962). Pennsy Power: Steam and Electric Locomotives of the Pennsylvania Railroad, 1900–1957. Staufer. LCCN 62020878.
  5. Warner, Paul T. (1924). Motive Power Development on the Pennsylvania railroad System. Philadelphia: Baldwin.
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