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The Pennsylvania Railroad's Q2 Duplex Locomotive.

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PRR Q2 4-4-6-4 Duplex Steam Locomotive
The Pennsylvania Railroad's class Q2 comprised one prototype and twenty-five production duplex steam locomotives of 4-4-6-4 wheel arrangement.

They were the largest non-articulated locomotives ever built and the most powerful locomotives ever static tested, producing 7,987 cylinder horsepower (5,956 kW) on the PRR's static test plant. They were by far the most successful duplex type. The duplex propensity to slip was combated by an automatic slip control mechanism that reduced power to the slipping unit.

The Q2 locomotive was 78% more powerful than the locomotives that PRR had in service at the time, and the company claimed the Q2 could pull 125 freight cars at a speed of 50 mph (80 km/h).

Despite overall success, the Q2s were all out of service by 1951. With dieselization, they were the obvious first targets to be withdrawn since they were only a little more capable than the conventional J1 class 2-10-4s but with far higher operating and maintenance costs.

Pennsylvania Railroad class Q2 Overview
Type and origin
Power type: Steam
Builder: PRR Altoona shops
Build date: 1944–45
Total produced: 26
Configuration: 4-4-6-4
UIC class: 2'BC2'
Gauge: 4 ft 8 1⁄2 in (1,435 mm) standard gauge
Leading diameter: 36 in (0.914 m)
Driver diameter: 69 in (1.753 m)
Wheelbase: 26 ft 4.5 in (8.039 m) (driving)
Wheelbase: 20 ft 4 in (6.20 m) (rigid)
Wheelbase: 53 ft 5.5 in (16.294 m) (locomotive)
Wheelbase: 107 ft 7.5 in (32.804 m) (locomotive and tender)
Length: 124 ft 7.125 in (37.976 m) (locomotive and tender)
Width: 11 ft 4 in (3.45 m) (storm windows open)
Height: 16 ft 5.5 in (5.017 m)
Adhesive weight: 393,000 lb (178,000 kg)
Locomotive weight: 619,100 lb (280,800 kg)
Tender weight: 430,000 lb (195,000 kg)
Total weight: 1,049,100 lb (475,900 kg)
Tender type: PRR class 180F84, 8 axles, with conductor "doghouse"
Fuel type: Soft coal
Fuel capacity: 39.86 short tons (36.16 t; 35.59 long tons)
Water capacity: 19,020 US gal (72,000 l; 15,840 imp gal)
Boiler pressure: 300 psi (2.1 MPa)
Front cylinder: 19 3⁄4 in × 28 in (502 mm × 711 mm)
Rear cylinder: 23 3⁄4 in × 29 in (603 mm × 737 mm)
Performance figures
Power output 7,987 hp (5,956 kW)
Operator: Pennsylvania Railroad
Numbers: 6131, 6175–6199
Last run: 1951
Disposition: Scrapped

See also:


Duplex Locomotives

Steam Locomotives


Front angle view of a PRR Q2 in Crestline, Ohio.

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The Pennsylvania Railroad's Q2 Duplex Locomotive.
Front angle view of a PRR Q2 in Crestline, Ohio. - NFL Jerseys and Gear
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