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


Class Details by Steve Llanso of Sweat House Media

Class K-2-36 (Locobase 7086)

Data from NC&StL 1 - 1921 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. 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. 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."

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 Raildata collection.

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 NC & StL 1 - 1921 Loco Diagrams Clr Chts - Cranes.

Locobase 13499 shows the original 4 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. Locobase suspects the Philadelphia manufacturer simply built 4 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" piston valves for steam admission, 28 sq ft 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).

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 Raildata collection. 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.

Specifications by Steve Llanso of Sweat House Media
ClassK-2-36K-2A-37K-2B/C/D-41 - updatedK1-34K1A
Locobase ID7086 14091 7087 13500 13501
RailroadNashville, Chattanooga & St. Louis (NC&StL)Nashville, Chattanooga & St. Louis (NC&StL)Nashville, Chattanooga & St. Louis (NC&StL)Nashville, Chattanooga & St. Louis (NC&StL)Nashville, Chattanooga & St. Louis (NC&StL)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class35848
Road Numbers330-332 / 530-532333-337 / 533-537530-537500-503504-511
GaugeStdStdStdStdStd
Number Built358
BuilderBaldwinBaldwinNCSLNC&StLBaldwin
Year19111913192819121915
Valve GearWalschaertWalschaertWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase13'13'13'13.17'13'
Engine Wheelbase34.08'34.08'35.62'34.08'34.08'
Ratio of driving wheelbase to overall engine wheebase 0.38 0.38 0.36 0.39 0.38
Overall Wheelbase (engine & tender)67.83'38.29'69.17'62.58'69.33'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers157250 lbs158000 lbs165500 lbs137000 lbs137000 lbs
Engine Weight253550 lbs257000 lbs259800 lbs218000 lbs218000 lbs
Tender Light Weight156450 lbs153000 lbs148000 lbs128900 lbs166000 lbs
Total Engine and Tender Weight410000 lbs410000 lbs407800 lbs346900 lbs384000 lbs
Tender Water Capacity8500 gals8500 gals8000 gals6000 gals8000 gals
Tender Fuel Capacity (oil/coal)14 tons14 tons13.5 tons13 tons14 tons
Minimum weight of rail (calculated)87 lb/yard88 lb/yard92 lb/yard76 lb/yard76 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter72"72"72"69"69"
Boiler Pressure200 psi180 psi200 psi185 psi185 psi
Cylinders (dia x stroke)23" x 28"25" x 28"25" x 28"23" x 28"23" x 28"
Tractive Effort34973 lbs37188 lbs41319 lbs33756 lbs33756 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.50 4.25 4.01 4.06 4.06
Heating Ability
Firebox Area240 sq. ft241 sq. ft328 sq. ft225 sq. ft212.70 sq. ft
Grate Area66.70 sq. ft66.70 sq. ft66.50 sq. ft50.40 sq. ft52.40 sq. ft
Evaporative Heating Surface4943 sq. ft3794 sq. ft3881 sq. ft2946 sq. ft2890 sq. ft
Superheating Surface842 sq. ft810 sq. ft590 sq. ft592 sq. ft
Combined Heating Surface4943 sq. ft4636 sq. ft4691 sq. ft3536 sq. ft3482 sq. ft
Evaporative Heating Surface/Cylinder Volume367.11238.50243.97218.80214.64
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation13340120061330093249694
Same as above plus superheater percentage1334014167155611090911342
Same as above but substitute firebox area for grate area4800051188767524870146039
Power L11095017077193281482314666
Power MT460.55714.84772.40715.60708.02

Specifications by Steve Llanso of Sweat House Media
ClassK1A-37 - with syphons
Locobase ID5463
RailroadNashville, Chattanooga & St. Louis (NC&StL)
CountryUSA
Whyte4-6-2
Number in Class8
Road Numbers504-511
GaugeStd
Number Built
BuilderNC&StL
Year1928
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase13'
Engine Wheelbase34.08'
Ratio of driving wheelbase to overall engine wheebase 0.38
Overall Wheelbase (engine & tender)69.40'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers150000 lbs
Engine Weight237000 lbs
Tender Light Weight148000 lbs
Total Engine and Tender Weight385000 lbs
Tender Water Capacity8000 gals
Tender Fuel Capacity (oil/coal)13 tons
Minimum weight of rail (calculated)83 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter69"
Boiler Pressure200 psi
Cylinders (dia x stroke)23" x 28"
Tractive Effort36493 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.11
Heating Ability
Firebox Area262 sq. ft
Grate Area50.40 sq. ft
Evaporative Heating Surface2983 sq. ft
Superheating Surface590 sq. ft
Combined Heating Surface3573 sq. ft
Evaporative Heating Surface/Cylinder Volume221.55
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10080
Same as above plus superheater percentage11794
Same as above but substitute firebox area for grate area61308
Power L116404
Power MT723.29


If you have any railroad data such as diagram books, rail station plans or anything else that you would be willing to share, please contact us.