Western Pacific 2-8-8-2 "Chesapeake" Locomotives in the USA

Class M-137 (Locobase 332)

Data from tables in 1947 Locomotive Cyclopedia and WP 2 - 1946 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also "Western Pacific Operating 2-8-8-2 Type in Fast Freight Service", Railway Age, Volume 91, No 26 (26 December 1931), pp. 975-976; DeGolyer, Volumes 81, pp. 521+ and 82, pp. 344+; and "Locomotive Feed Water Heaters,", Boiler Maker, Volume 22, No 10 (October 1922), pp. 292-294. (Thanks to Andrew S for his 30 March 2024 email noting the two subclasses of 2-8-8-2s on the WP, which prompted the addition of Locobase 16669.Thanks too to Chris Hohl, whose 1 February 2025 email reported that boiler pressure went up to 250 psi.) Works numbers were 61636-61637, 61641-61642, 61648-61649 in July 1931

Ten of these big articulateds were built for the Feather River Canyon route. This entry gives details for the first six, supplied by Baldwin according to spec 31-D-94. Locobase 16669 describes the last four of the class, which Eddystone built to a 38-D-39 revised spec.

The class hauled Pacific Fruit Express trains (65-74 cars) through the canyon and up a 1% grade at speeds of 18-25 mph (29-40 kph) over a distance of 117 miles (188 km) from Oroville to Portola. The WP had been using two 2-6-6-2s, a 2-6-6-2 and a 2-8-2, or a double-headed set of 2-8-8-2 and 2-8-0 locomotives.

The 251s were oil-fired engines with immense firebox areas. Firebox and combustion chamber had Nicholson thermic syphons which contributed considerably to the heating surface area; three were in the firebox, two in the combustion chamber. The thermic syphons alone amounted to 217 sq ft (20.15 sq m) and the combustion chamber added another 155 sq ft (14.4 sq m). Sometime before 1943, the WP raised the working pressure setting to 250 psi (17.25 bar)..

When delivered, two of the boilers were fitted with Worthington No 6 Type S open-system feedwater heater and four used the Elesco Type K-60 closed-system. Four 12" (305 mm) piston valves fed the cylinders.

A report in the Boiler Maker in 1922 discussed "one of the most important considerations" when choosing between Worthington's open system, where the hot steam was blended directly with the incoming water, and the closed system of Elesco and Coffin, which passed the feed water through a tube in the center of a steam-filled chamber. In bad water districts, said the report, the closed type heater built up scale on the tubes that would "retard the heat transmitted and reduce the efficiency of the heater." One clear result from the difference was that the Worthington could operate from shopping to shopping without being cleaned.

The RA article reported that preliminary tests showed that one M-137 could handle trains of similar tonnage to the earlier consists and with approximately the same fuel consumption".

As good as the class was, the WP soon tested the EMD four-diesel set and plumped for diesels sooner than most other US railroads. As a result, the entire class of M-137s was scrapped in the early 1950s.

Class M-137-257 (Locobase 16669)

Data from WP 2 - 1946 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange; and "Western Pacific 2-8-8-2 Type Locomotives", Baldwin Magazine, Volume 17, No 1 (July 1938), pp. 18-19. (Thanks to Andrew S for his 30 March 2024 email noting the two subclasses of 2-8-8-2s on the WP; it prompted the drafting this entry.) Works numbers were 62149-62152 in 1938.

Ten of these big articulateds were built for the Feather River Canyon route. Locobase 332 describes the first six, built to the 31-D-94 specification. Seven years later, the WP ordered four more to a modified 38-D-39 spec. Baldwin Magazine said that the most important change was "the substitution of a cast steel locomotive bed with integral cylinders for each [engine] unit.in place of the bar frames formerly used."

Like the 251s, this quartet hauled Pacific Fruit Express trains (65-74 cars) through the canyon and up a 1% grade at speeds of 18-25 mph (29-40 kph) over a distance of 117 miles (188 km) from Oroville to Portola.

These were oil-fired engines with immense firebox areas. Firebox and combustion chamber had Nicholson thermic syphons which contributed considerably to the heating surface area; three were in the firebox, two in the combustion chamber. A significant modification reduced thermic syphon count in the firebox to two and area by 79 sq ft (7.34 sq m) to 148 sq ft (13.73 sq m); the combustion chamber kept its two syphons for another 155 sq ft (14.4 sq m). Still later, the firebox syphon count remained the same, but the shops removed one of the two in the combustion chamber.

Each of the four cylinders used a 12" (305 mm) piston valve to admit steam.

Another change adopted Coffin C-2 closed system feed water heaters in place of either the Elesco (closed) or the Worthingtons (open) used in the first batch.

As good as the class was, the WP soon tested the EMD four-diesel set and plumped for diesels sooner than most other US railroads. As a result, the entire class of M-137s was scrapped in the early 1950s.