Philadelphia 2-2-0 "Planet" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Ransom (Locobase 12251)

Data from "Steam on Street Railways - Part II", Journal of the Franklin Institute, July 1877, pp. 68- . See also "Steam Cars on City Passenger Railways," Railway World, Quarto Volume 3, No 12 (24 March 1877), p. 268.

Although Baldwin was experimenting with tram motors (Locobase 8429), Louis Ransom's design was the first to hit Philadelphia streets in any number. They engaged in trials by the Market Street Passenger Railway Company.

Most tram motors were designed to resemble tram cars and Ransom's car was no different although the wheelbase was a bit longer than typical horse-drawn trams. The upright boiler occupied the front of the car.

Under the car was the drive train, which was housed in "...a box or casing so perfectly dust-tight, that after running all day through the dusty streets, the engine is not only free from dust, but covered with drops of water, condensed from the slight escape of steam from the stuffing boxes."

Ransom favored the inside-cylinder, crank-axle layout, which placed him at odds with many of his contemporaries. In addition to the reduced "boxing" and high-speed vibration that resulted from placing the cylinders so close to the centerline, the compactness of the arrangement allowed for the better protection afforded by the casing described above.

The cylinders were cast in one piece and provided the front anchorages for the engine frame and journal boxes on the driving axle in the rear, thus isolating the car itself from wracking. Although the slide valves were operated by a link motion involving two eccentrics, the link remained stationary and a pin connected to the valve rod slid up and down .

The cylinders were secured in front by a "bale", an open triangle with the top vertex mounted on the car and the outside ends holding up pins on each outside edge of the cylinders.

The Journal concluded with a discussion of the design's accessibility and other virtues:

"The whole propelling apparatus, being supported at three points, is not easily racked or injured by derailment, gives great flexibility and is easily removed in case of extensive repairs; when slight repairs are needed the car can be run over a pit, the front end of the engine detached and allowed to hang down from the crank axle like a pendulum. The machine is also accessible for cleaning, oiling, packing, etc., through trap-doors in the floor of the car."

Unfortunately, the Ransom simply wasn't powerful enough to handle the Baring Street branch's gradients and curves. His proposal to mount 7" (177 mm) cylinders and fit steel wheels to increase tractive power apparently was not taken up. Moreover, combining passenger accommodation (20 seats but up to 50 riders) with the noise, heat, and vibration of the engine in the same car proved very unpopular.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID12,251
Number in Class6
Road Numbers
Number Built6
BuilderGilbert, Bush & Company
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)7 / 2.13
Engine Wheelbase (ft / m)7 / 2.13
Ratio of driving wheelbase to overall engine wheebase1
Overall Wheelbase (engine & tender) (ft / m)7 / 2.13
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)
Engine Weight (lbs / kg)
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)400 / 1.52
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)35 / 889
Boiler Pressure (psi / kPa)120 / 8.30
High Pressure Cylinders (dia x stroke) (in / mm)5.5" x 14" / 140x356
Tractive Effort (lbs / kg)1234 / 559.73
Factor of Adhesion (Weight on Drivers/Tractive Effort)
Heating Ability
Firebox Area (sq ft / m2)18 / 1.67
Grate Area (sq ft / m2) 6.50 / 0.60
Evaporative Heating Surface (sq ft / m2)116 / 10.78
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)116 / 10.78
Evaporative Heating Surface/Cylinder Volume301.32
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation780
Same as above plus superheater percentage780
Same as above but substitute firebox area for grate area2160
Power L13746
Power MT

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