Bachmann, HO Scale, 84406, Pre-War K4 4-6-2 with Slat Pilot, Pennsylvania Railroad, #5492

History of the K4 4-6-2 Steam Engine

The K4 4-6-2, also known as the "Pacific" type, was a class of steam locomotives built by the Pennsylvania Railroad (PRR) between 1914 and 1928. Designed by J.T. Wallis, Alfred W. Gibbs, and Axel Vogt, the K4s were built to haul mainline passenger trains across the PRR system.

Production and Railroads

• Total Units: 425 locomotives were produced.

• Railroads: The primary user was the Pennsylvania Railroad, but other railroads, such as the Duluth, Missabe & Iron Range Railway, Northern Pacific Railway, and Southern Pacific Railroad, also operated the K4s.

Usage

The K4s were known for their speed, stability, and power, making them ideal for passenger service. They hauled prestigious trains like the Broadway Limited, competing with rival railroads for passengers traveling between major cities like New York, Philadelphia, and Chicago. During World War II, the K4s were stretched to their limits, hauling both troop trains and regular passenger services.

Technical Specifications

• Configuration: 4-6-2 (Whyte notation)

• Gauge: 4 ft 8 + 1⁄2 in (1,435 mm)

• Leading Diameter: 36 in (914 mm)

• Driver Diameter: 80 in (2,032 mm)

• Trailing Diameter: 50 in (1,270 mm)

• Boiler Pressure: 205 psi (1.41 MPa)

• Cylinder Size: 27 in × 28 in (686 mm × 711 mm)

• Maximum Speed: 87 mph (140 km/h)

• Tractive Effort: 44,460 lbf (197.8 kN)

Legacy

Despite the introduction of newer locomotives like the K5 and the T1 duplex, the K4s remained the PRR's primary express passenger locomotives for 30-40 years. Many K4s were double-headed or triple-headed to handle the heavier trains from the mid-1930s onward. Today, only a few K4s remain preserved, with Nos. 1361 and 3750 designated as Pennsylvania's official state steam locomotives.