Baltimore & Ohio 4-2-0 "Jervis" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Lafayette (Locobase 2542)

Data from Alvin F Staufer, Steam and Electric Locomotives of the Baltimore and Ohio (Medina, OH: Alvin F Staufer, 1964), p. 6. "Old Time Locomotive Performances", Railway Age, Volume 22 (25 December 1896), pp. 507-508. (Thanks to Chris Hohl for his 22 March 2018 email directing me to Staufer's diagram.

Based on the Philadelphia & Columbia's Washington County Farmer, this engine was a typical William Norris design. It had the Bury "haystack" boiler, a bar (vs plate) frame, and a valve gear that was cam-operated. Hollingsworth (1982) notes that later engines in the class had a more typical "gab" motion.

Hollingsworth contends that these engines were a great success, being reliable and showing markedly reduced fuel consumption. William Norris, whose 3 April 1837 report on his locomotives is reproduced in the 1896 article, certainly agreed. He described in detail tests that demonstrated pulling power that he claimed was typical of every-day results:

"The La Fayette is performing daily on the Columbia railway, and any persons can, at any time, see for themselves the immense powers of this engine. She drags with ease 25 loaded cars, over abrupt curves and high grades, and on a rise of 52 feet per mile, with the actual weight of 241,275 pounds [120.6 short tons or 109.4 metric tonnes] (taken from the weighmaster's books), attached to her; she has come to a dead stand, and started again without the least difficulty in a state of rest. On Friday last, March 31, this engine brought in, attached to her, the unprecedented and enormous load of 45 cars, 25 of which were loaded, and this load she carried over the grade of 52 feet rise per mile, without any difficulty, not a single instant's delay, but steadily at the rate of nearly 9 miles per hour [14.5 kph]."

With reason, Norris closed by challenging: "Let unbelievers come and see for themselves."

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID2542
RailroadBaltimore & Ohio (B&O)
Number in Class8
Road Numbers
Number Built8
BuilderWilliam Norris
Valve Gear
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m) 9.40 / 2.87
Ratio of driving wheelbase to overall engine wheebase
Overall Wheelbase (engine & tender) (ft / m)29 / 8.84
Axle Loading (Maximum Weight per Axle) (lbs / kg)18,030 / 8178
Weight on Drivers (lbs / kg)18,030 / 8178
Engine Weight (lbs / kg)29,200 / 13,245
Tender Loaded Weight (lbs / kg)11,820 / 5361
Total Engine and Tender Weight (lbs / kg)41,020 / 18,606
Tender Water Capacity (gals / ML)600 / 2.27
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT) 0.70 / 0.60
Minimum weight of rail (calculated) (lb/yd / kg/m)30 / 15
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)48 / 1219
Boiler Pressure (psi / kPa)90 / 6.20
High Pressure Cylinders (dia x stroke) (in / mm)9" x 18" / 229x457
Tractive Effort (lbs / kg)2324 / 1054.15
Factor of Adhesion (Weight on Drivers/Tractive Effort) 7.76
Heating Ability
Firebox Area (sq ft / m2)33.80 / 3.14
Grate Area (sq ft / m2) 5.60 / 0.52
Evaporative Heating Surface (sq ft / m2)265 / 24.62
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)265 / 24.62
Evaporative Heating Surface/Cylinder Volume199.95
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation504
Same as above plus superheater percentage504
Same as above but substitute firebox area for grate area3042
Power L12358
Power MT288.32

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