Baltimore & Ohio 0-2-2 Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Tom Thumb (Locobase 1015)

Data from Alvin F Staufer's Baltimore & Ohio Steam and Electric Locomotives (Medina, Ohio) supplied by Allen Stanley from his extensive Rail Data Exchange May 2005.

This tiny engine was built by Peter Cooper to show that automotive power was possible for the new B&O. Inside a 5-foot tall vertical boiler were a firebox and boiler flues cobbled together from musket barrels. Cooper kept the vehicle short to ensure that he could negotiate the tightest curves. Kinert perhaps overstates Cooper's ingenuity when he claims that Cooper preceded Stephenson in the use of a multi-tube boiler and forced draft. (Stephenson's layout would be widely used; Cooper's not at all.)

In size a powered handcar, Tom Thumb was gear-driven, the cylinder rod turning a flywheel through a crank as the flywheel teeth engaged the front wheels. It nearly won its demonstration race against a horse-drawn rival until its fan-blower drive belt slipped off again.

Kinert 1962, Sagle 1964, Comstock 1971

Principal Dimensions by Steve Llanso of Sweat House Media
ClassTom Thumb
Locobase ID1015
RailroadBaltimore & Ohio (B&O)
Number in Class1
Road Numbers
Number Built1
BuilderPeter Cooper
Valve Gear
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)13.24 / 4.04
Ratio of driving wheelbase to overall engine wheebase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)5800 / 2631
Engine Weight (lbs / kg)10,800 / 4899
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)52 / 0.20
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT) 0.40 / 0.40
Minimum weight of rail (calculated) (lb/yd / kg/m)
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)30.20 / 767
Boiler Pressure (psi / kPa)90 / 6.20
High Pressure Cylinders (dia x stroke) (in / mm)5" x 27" / 127x686 (1)
Tractive Effort (lbs / kg)855 / 387.82
Factor of Adhesion (Weight on Drivers/Tractive Effort) 6.78
Heating Ability
Firebox Area (sq ft / m2)11.50 / 1.07
Grate Area (sq ft / m2) 2.70 / 0.25
Evaporative Heating Surface (sq ft / m2)40 / 3.72
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)40 / 3.72
Evaporative Heating Surface/Cylinder Volume130.38
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation243
Same as above plus superheater percentage243
Same as above but substitute firebox area for grate area1035
Power L11440
Power MT