Pennsylvania 2-4-6 Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Old L/""Jumbo"" (Locobase 5489)

Data from (Viewed 11 April 2003). See also the Christopher T Baer, "A General Chronology Of The Pennsylvania Railroad Company, Its Predecessors And Successors and Its Historical Context -- 1882", Pennsylvania Railroad Historical Society, last updated November 2015, archived online at [], last accessed 12 January 2018. (Thanks to Chris Hohl for his 3 January 2018 email noting the L's road number.). Works number was 645 in 1882.

According to William Edson's exhaustive compilation, this locomotive was designed by Theodore N. Ely. The arrangement looks very much like a Mason Bogie suburban tank engine. 2-4-6Ts (56-60, 1883) ran on the Long Island Railroad, but these were quite a bit smaller. The firebox on the L class was shallow, narrow and long with a sharply sloped backhead--all characteristics of the Altoona boiler. Tube length was exceptional for the time as well, only rivalled the Santa Fe 4-8-0s shown in Locobase 8996.

The L's nickname came from its then great size and reflected the recent arrival of P T Barnum's enormous elephant and its immediate adoption as a template for largeness.

The Jumbo only operated for about 11 years and was scrapped in October 1893

Principal Dimensions by Steve Llanso of Sweat House Media
ClassOld L/""Jumbo""
Locobase ID5489
RailroadPennsylvania (PRR)
Number in Class1
Road Numbers4
Number Built1
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)7 / 2.13
Engine Wheelbase (ft / m)31.33 / 9.55
Ratio of driving wheelbase to overall engine wheebase 0.22
Overall Wheelbase (engine & tender) (ft / m)31.33 / 9.55
Axle Loading (Maximum Weight per Axle) (lbs / kg)32,500 / 14,742
Weight on Drivers (lbs / kg)59,750 / 27,102
Engine Weight (lbs / kg)124,100 / 56,291
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)124,100
Tender Water Capacity (gals / ML)1680 / 6.36
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT) 1.50 / 1.40
Minimum weight of rail (calculated) (lb/yd / kg/m)50 / 25
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)62 / 1575
Boiler Pressure (psi / kPa)125 / 8.60
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x610
Tractive Effort (lbs / kg)11,886 / 5391.41
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.03
Heating Ability
Firebox Area (sq ft / m2)
Grate Area (sq ft / m2)21.05 / 1.96
Evaporative Heating Surface (sq ft / m2)
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)
Evaporative Heating Surface/Cylinder Volume
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2631
Same as above plus superheater percentage2631
Same as above but substitute firebox area for grate area
Power L1
Power MT

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Wes Barris