Southern Railway Ps-4 class

Southern Railway class Ps-4 4-6-2
ALCO Richmond built Ps-4 no. 1396 built in 1926.
Type and origin Power type Steam Builder ALCO Schenectady (1923 order) ALCO Richmond (1926 order) Baldwin Locomotive Works (1928 order) Build date 1923-1928 Total produced 64
Specifications Configuration: ​  • Whyte 4-6-2 "Pacific" Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Driver dia. 73 in (1,850 mm) Wheelbase 13 ft 0 in (3.962 m) Frame type Bar Axle load 61 long tons (62.0 t) Adhesive weight 182,000 lbf (809.6 kN) Tender type 3 axle bogie (1926 order), 2 axle bogie (1923 and 1928 orders) Fuel type Coal Fuel capacity 16 long tons (16.3 t) Water cap 14,000 imp gal (64,000 l) (1926 order), 12,000 imp gal (55,000 l) (1928 order) Firebox:  • Firegrate area 70.5 sq ft (6.550 m2) Boiler pressure 200 psi (1,380 kPa) Feedwater heater Worthington(1923 order), Elesco(1926 and 1928 orders), Coffin(SR no. 1409 only) Cylinders Two Cylinder size 27 in (686 mm) bore 28 in (711 mm) stroke Valve gear Baker, Walschaerts (1928 order)
Performance figures Tractive effort 47,500 lbf (211.3 kN)
Career Operators Southern Railway, Alabama Great Southern Railroad, Cincinnati, New Orleans and Texas Pacific Railway Class Class Ps-4 Number in class 64 Numbers SR #1375-1409, AGS #6684-6690, CNO&TP #6471-6482 Delivered 1923-1928 Withdrawn 1949 - 1953 Preserved SR #1401 Disposition one preserved, remainder scrapped

The Ps-4 class was a class of 4-6-2 steam locomotives built for the Southern Railway, as well as its subsidiaries, the Alabama Great Southern Railroad and the Cincinnati, New Orleans and Texas Pacific Railway. The engines are notable for their green with gold trim liveries, and have been regarded by Smithsonian curator John H. White, Jr. as being "among the most celebrated passenger locomotives operated in the United States...."

In 1923, the Southern Railway began placing an order for new locomotives of the 4-6-2 Pacific design capable of handling up to fourteen cars over a moderate grade, as well as top speeds of 80 miles per hour (130 km/h). The first group of engines were built by the American Locomotive Company at their Schenectady Works in that year, with twenty six delivered to the Southern, numbered 1363-1392; as well as five for the Cincinnati, New Orleans and Texas Pacific, numbered 6471-6475; and four for the Alabama Great Southern, numbered 6684-6687. These engines were derived from the standard USRA Light Pacific design, but had notable differences based on the Southern's needs. The Ps-4s had smaller driving wheels (73 inches vs. 79 inch USRA design), as well as larger, more spacious cabs, and featured single unit 3-B Worthington feedwater heaters under the left-hand running boards.

In 1925, Southern president Fairfax Harrison traveled to the United Kingdom, where he admired that country's Southern Railway's use of green-painted steam locomotives. Harrison's trip inspired the appearance of the second order of Ps-4s, which was being built by ALCO's Richmond Works at the time. These Ps-4s were delivered in 1926, painted mostly green (a somewhat different shade, more akin to that used by the London and North Eastern Railway), with gold trim and silver smoke-boxes. This order consisted of eleven engines for the Southern, numbered 1393-1404; seven for the Cincinnati, New Orleans and Texas Pacific, numbered 6476-6482; and four for the Alabama Great Southern, numbered 6688-6691. Aside from the paint scheme, which would soon be applied to all of Southern's passenger locomotives, the second order had other notable differences. They featured an Elesco feedwater heater rather than the Worthington heaters of the previous order, with the former placed on top of the smokebox between the stack and bell instead of under the running boards as the latter were placed. The second order also had larger tenders better suited for long-distance passenger runs, with three-axle bogies and 14,000 gallon water capacity, versus the two-axle bogie, 10,000 gallon standard USRA tender design of the first order.