Nashville, Chattanooga & St. Louis 4-6-2 "Pacific" Locomotives in the USA

Class K-2-36 (Locobase 7086)

Data from NC&StL 1 - 1921 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also "Pacific Type Locomotives", American Engineer, Volume 86, Number 3 (March 1912), pp. 141-142 and Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 40, p. Works numbers were 37410-37411 in December 1911 and 37415 in January 1912.

These were the heavyweight express engines on the Dixie Line when they entered service. Their relatively small drivers speak to the undulating profile of most of this railroad's territory. Their duties included a 151-mile run in 4 hours 17 minutes making 6 stops while pulling 12 cars. AE's report added: "The hilly nature of the country makes this a very severe schedule requiring a locomotive of considerable reserve power."

The 1911 Baldwin specs show how closely tolerances had to be measured when C G Herman reported on 4 March 1912 that the "Front end of engines too high. It was found necessary to make Engine Truck center pin 7/8" shorter, to lower the front end and make the engine set level." Inevitably, this led to other adjustments: "This necessitated the raising of the pilot on the bumper, to keep it the proper distance from the rail." And the front spring heights needed to be checked.

There was more. the longitudinal back equal[izing] beams that linked the rearmost driven axle to the trailing truck proved too weak. "Hereafter, make them stronger and of wrot [sic - it was a common spelling] iron."

The 1913 batch of five more Pacifics is shown in Locobase 14091.

Over time, the engines were rebuilt and the result is shown in Locobase 7087.

Class K-2A-37 (Locobase 14091)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 46, p. 267. See also "Pacific-Type Locomotive for the Nashville, Chattanooga & St Louis Ry.", Railway and Engineering Review, Volume 53, No 25 (21 June 1913), pp. 586-588. Works numbers were 39448-39452 in March 1913.

Locobase 7086 shows the first three K2s, which were delivered with saturated boilers. Two years later, this quintet of Pacifics constituted the superheated variant, which sacrificed 199 small tubes for the 34 flues that held the superheater elements. The specs included the requirement that the engines have a "cylinder pattern for 30" stroke, with piston head 2" wider than normal, so as to provide proper clearance between heads when using 28" stroke." Fifteen-inch (381 mm) piston valves supplied steam to the cylinders.

R&ER's report noted that the sizable boiler ws "obtained without cramping the tubes or impeding circulation, as the small 2-inch tubes are spaced with 7/8-inch [22.23 mm] bridges and the mud ring has a uniform width of 5 inches." The firebox also had abrick arch.

Later, the Dixie Line revamped all eight K2s with much more direct heating surface area; see Locobase 7087.

Class K-2B/C/D-41 - updated (Locobase 7087)

Data from NC&StL 2 - 1947 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Over time, the K2 engines first procured in 1911-1913 (see Locobase 7086) were rebuilt with feedwater heaters and the firebox heating surface then amounted to 328 sq ft of which 14 sq ft were arch tubes (14.8 sq ft fewer than originally installed) and 73 sq ft of thermic syphons. At the same time, boiler pressure grew to 200 psi and the cylinder diameter increased by an inch.

Two - 535-536 -- were streamlined for the Dixie Flagler (1940) and the City of Memphis. 535 later gained a cast-steel frame, Timken roller bearings on all axles and a bigger tender that held 16 tons of coal and 15,000 gallons of water. Drury (1993) says this streamliner averaged 14,000 miles/month for several years on the Memphis-Nashville run.

Class K1-34 (Locobase 13500)

Data from DeGolyer, Volume 51, pp. 221+ and NC & StL 1 - 1921 Loco Diagrams Clr Chts - Cranes.

Locobase 13499 shows the original four Ten-wheelers. Once they were returned to Baldwin, the builder "modified" the engines by removing the Baldwin smokebox superheaters and replacing the entire boiler and firebox as far as Locobase can judge. In addition, cylinder size shrank by an inch and boiler pressure was reduced by 15 psi (1.03 bar) Locobase suspects the Philadelphia manufacturer simply built four new Pacifics.

The old/new engines were quite satisfactory and 8 were built to a slightly different design in 1915 (Locobase 13501). The class had 13"(330 mm) piston valves for steam admission, 28 sq ft (2.60 sq m) of arch tubes contributing to the heating surface, and a middling amount of superheater area.

All remained in service until the late 1940s.

Class K1A (Locobase 13501)

Data from NC & StL 1 - 1921 Loco Diagrams Clr Chts - Cranes. DeGolyer, Volume 51, pp. 215+. (Thanks to Chris Hohl for his 7 March 2016 email noting the correct tender capacity, boiler pressure, and class ID.) Works numbers were 41909-41911 in February 1915, 41933-41935 in March, and 42612-42613 in October.

These were very similar to the Baldwins that had been "rebuilt" from unsatisfactory Ten-wheelers in 1912 (Locobase 13500). Both had 13" (330 mm) piston valves and a moderately sized superheater. But these were built new. They trailed cylindrical Vanderbilt tenders and had arch tubes that contributed 26.6 sq ft (2.47 sq m). Baldwin's figures for evaporative heating surface area are said by the diagram to represent a boiler with 186 small tubes. Their calculations suggest, however, that they had reduced the count to 182, probably at the request of the railroad, which showed the latter figure in its 1921 diagram.

By 1921, the NC&StL diagrams showed weights had grown both on the drivers (to 150,000 lb/68,039 kg) and on all engine axles (237,000 lb/107,502 kg). Light weight for the engine was shown as 215,360 lb (97,686 kg). There are other differences that, taken together, suggest that the railroad rebuilt the locomotive's boiler quite soon after delivery. Grate area was now figured at 50.4 sq ft (4.68 sq m) and the firebox heating surface area was calculated at 225 sq ft (20.9 sq m). Perhaps at the same time, the firebox received two thermic syphons, which contributed 65 sq ft (6.04 sq m).

And all served the hilly profiles of the NC & StL until the late 1940s.

Class K1A-37 - with syphons (Locobase 5463)

Data from NC&StL 6 - 1951 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were 41909-41911 in February, 41933-41935 in March, 42612-42613 in October.

Relatively small Pacifics for Atlanta Division main and local passenger service. When delivered, their boilers were pressed to 185 psi ; see Locobase 13501. A later rebuild deleted the arch tubes in favor of 65 sq ft of thermic syphons as part of firebox heating surface, which resulted in the figure shown in the specifications.

The last of these was retired in 1948.