Sharp and Fellows No 7, built by ALCO (Dickson) No. 26264, in December of 1902), a 2-6-2 steam locomotive at Travel Town Museum, Los Angeles, CA in 2010.
(Carl Morrison, CC0, via Wikimedia Commons)
2-6-2 PRAIRIE STEAM LOCOMOTIVE
Under the Whyte notation for the classification of steam locomotives, 2-6-2 represents the wheel arrangement of two leading wheels, six coupled driving wheels and two trailing wheels. This arrangement is commonly called a Prairie.
Schematic of 2-6-2 steam locomotive wheel arrangement. Front of locomotive on left.
(Gwernol, Public domain, via Wikimedia Commons)
Beginnings
The majority of American 2-6-2s were tender locomotives, but in Europe tank locomotives, described as 2-6-2T, were more common. The first 2-6-2 tender locomotives for a North American customer were built by Brooks Locomotive Works in 1900 for the Chicago, Burlington and Quincy Railroad, for use on the Midwestern prairies. The type was thus nicknamed the Prairie in North American practice. This name was often also used for British locomotives with this wheel arrangement.
As with the 2-10-2, the major problem with the 2-6-2 is that these engines have a symmetrical wheel layout, with the center of gravity almost over the center driving wheel. The reciprocation rods, when working near the center of gravity, induce severe side-to-side nosing which results in intense instability if unrestrained either by a long wheelbase or by the leading and trailing trucks. Though some engines, like the Chicago and Great Western of 1903, had the connecting rod aligned onto the third driver, most examples were powered via the second driver and were prone to the nosing problem.
A 2-6-2 Prairie steam locomotive built in the United States by the Baldwin Locomotive Works for the Chicago, Burlington and Quincy Railroad. (1922 Locomotive Cyclopedia of American Practice, Public domain, Wikimedia Commons)
A Lake Shore and Michigan Southern Railway 2-6-2 Prairie locomotive. (Howden, Boys' Book of Locomotives, 1907, Public domain, Wikimedia Commons)
Usage
United States
Narrow gauge
The 2 ft (610 mm) gauge Sandy River and Rangeley Lakes Railroad in Franklin County, Maine, was a major narrow gauge 2-6-2 user.
Standard gauge
In the United States, the type evolved from the 2-6-0 Mogul configuration. The Atchison, Topeka and Santa Fe Railway (AT&SF) became a pioneer of the type in the United States in 1901 and one of the largest fleet users of the type. Problems the road encountered with the type included steam leakage in the compound cylinder plumbing and instability at speed. The former problem was solved by converting them to simplex two-cylinder locomotives; the latter problem required new 4-6-2 Pacific types with four-wheeled guide trucks. The Prairie types were rebuilt with smaller drivers for slightly slower fast freight service. These engines tended to enjoy very long service lives, and outlasted many a newer, more efficient steam locomotive on the Santa Fe and elsewhere. This was due to their modest weight, good speed and ability to operate well in reverse, which made them valuable for branch line operations.
In 1902, the AT&SF had a 2-6-2 with a high, at the time, boiler pressure of 220 pounds per square inch (1,517 kPa), mounted on a large 41-square-foot (3.8-m2) fire grate.
More than a thousand examples of the 2-6-2 wheel arrangement existed in the United States. Of these, one hundred were high-wheeled engines with larger than 69-inch (1,753-mm) drivers. The Lake Shore & Michigan Southern (see photo) operated locomotives with 80-inch (2,032-mm) drivers, but this did not overcome their inherent instability. They were never as successful in passenger service in the U.S. as they were in other nations.
Postcard photo of a 2-6-2 "Prairie" locomotive of the Chicago, Milwaukee and St. Paul Railway. The locomotive was No. 2071 and lettered "CM&STP OF WASHINGTON".
The 2071, class K1, was built by Milwaukee Shops in September 1908; renumbered 5571 in 1912; and scrapped March 1935.
(Photographer was D. Melger, Kirkland, Illinois., Public domain, via Wikimedia Commons)
Overview
Equivalent classifications
UIC class: 1C1, 1'C1'
French class: 131
Turkish class: 35
Swiss class: 3/5
Russian class: 1-3-1
First known tank engine version
First use: 1875
Country: Cape of Good Hope
Locomotive: CGR 2nd Class 2-6-2TT
Railway: Cape Government Railways
Designer: Robert Stephenson and Company
Builder: Robert Stephenson and Company
Benefits: Better stability than a mogul
First known tender engine version
First use: 1884
Country: New Zealand
Railway: New Zealand Railways Department
Builder: Nasmyth, Wilson and Company
Evolved from: 2-6-0