Carolina, Clinchfield & Ohio 4-6-2 "Pacific" Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class P-1 (Locobase 3089)

Data from "Freight (2-6-6-2) and Passsenger Locomotives for a Low Grade Line," American Engineer and Railroad Journal (September 1910 ), pp. 357-358; DeGolyer, Volume 45, pp. 297+; and from Clinch 1943ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were 34808-34809, 34882 - all in June 1910.

These were the first Pacifics on the Clinchfield (more formally the Carolina, Clinchfield, and Ohio). The P-1s had inside valves and outside valve gear, an extended smokebox, spread domes with the bell between, and coned second course to the boiler. The AERJ report comments on the balance needed to deliver good passenger power in a discussion that anticipates many of the goals later set by Lima's Woolard in the Super-power revolution of the 1920s:

"A large theoretical tractive effort on ...any locomotive ...is meaningless unless it is backed up by sufficient boiler capacity to make it available at other than very low speeds. This feature in this case is well taken care of ...by the large size of the boiler and the liberal spacing of the flues. The BD factor of 625 and a ratio of heating surface to cylinder volume of 283 do not clearly indicate the probable steam making capacity of the boiler."

But the writer did not acknowledge the now-rapid growth in superheater applications and still saw things in a saturated perspective. Noting the large extended wagon top boiler's considerable girth at both the front end and the length and number of tubes, he concluded : "...it is evident that with a good grade of fuel it will be possible to make and free all the steam necessary and that the steam storage space is sufficient to furnish a reasonable dry supply for the cylinders." In the case of the P-1, this facility must have been abetted by the large 15" (381 mm)diameter piston valves.

They served until 1951 and were never superheated.


Class P-2 (Locobase 1322)

Data from Railway Age (November 1914). See also DeGolyer, Vol 50, pp. 126-134. Works numbers were 41679-41680 in September 1914.

Firebox heating surface included 30 sq ft of arch tubes.

As might be expected on a mountain-profiled coal railroad, these passenger-type Pacifics also pulled fast freights. They followed an earlier group of three that had smaller cylinders.

Railway Age noted the hilly terrain over which they had to operate and said that passenger engines in such service "must have capacity to maintain a high drawbar pull for sustained periods, rather than the ability to run at unusually high speeds." This meant high tractive effort and a boiler big enough to supply steam even for long periods of late-cutoff operation. Note the relatively generous superheat and the relatively high cross-sectional area of the tubes and flues compared to the grate area (the A/S ratio).

No complaints here; the engines ran until 1953.

Specifications by Steve Llanso of Sweat House Media
ClassP-1P-2
Locobase ID3089 1322
RailroadCarolina, Clinchfield & Ohio (Clinchfield)Carolina, Clinchfield & Ohio (Clinchfield)
CountryUSAUSA
Whyte4-6-24-6-2
Number in Class32
Road Numbers150-152153-154
GaugeStdStd
Number Built32
BuilderBaldwinBaldwin
Year19101914
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13 / 3.9613 / 3.96
Engine Wheelbase (ft / m)34.75 / 10.5934.50 / 10.52
Ratio of driving wheelbase to overall engine wheebase 0.37 0.38
Overall Wheelbase (engine & tender) (ft / m)66.21 / 20.1866.94 / 20.40
Axle Loading (Maximum Weight per Axle) (lbs / kg)52,500 / 23,81460,300 / 27,352
Weight on Drivers (lbs / kg)152,900 / 69,354176,900 / 80,241
Engine Weight (lbs / kg)233,050 / 105,710280,300 / 127,142
Tender Loaded Weight (lbs / kg)151,950 / 68,923154,600 / 70,125
Total Engine and Tender Weight (lbs / kg)385,000 / 174,633434,900 / 197,267
Tender Water Capacity (gals / ML)8000 / 30.308000 / 30.30
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)14 / 12.7014 / 12.70
Minimum weight of rail (calculated) (lb/yd / kg/m)85 / 42.5098 / 49
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 175369 / 1753
Boiler Pressure (psi / kPa)190 / 13.10200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)23" x 30" / 584x76225" x 30" / 635x762
Tractive Effort (lbs / kg)37,145 / 16848.7146,196 / 20954.18
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.12 3.83
Heating Ability
Firebox Area (sq ft / m2)192 / 17.84238 / 22.11
Grate Area (sq ft / m2)54 / 5.0253.80 / 5
Evaporative Heating Surface (sq ft / m2)4095 / 380.583982 / 369.94
Superheating Surface (sq ft / m2)955 / 88.72
Combined Heating Surface (sq ft / m2)4095 / 380.584937 / 458.66
Evaporative Heating Surface/Cylinder Volume283.86233.63
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10,26010,760
Same as above plus superheater percentage10,26012,804
Same as above but substitute firebox area for grate area36,48056,644
Power L1765618,578
Power MT331.17694.59