Richmond, Fredericksburg & Potomac 4-8-2 "Mountain" Locomotives of the USA

The Richmond Fredericksburg & Potomac bought two 4-8-2 "Mountains" (road numbers 200 and 201) from the American Locomotive Company in 1924 and two more (road numbers 202 and 203) in 1925, also from ALCO. Apparently, these were almost immediately renumberd to 501-504.

These four locomotives had 28 x 30 cylinders, 73" drivers and a 210 psi boiler pressure which gave them 57,500 pounds of tractive effort. Each weighed 381,000 pounds and were 93" - 6" long (including tenders). The tender had a 10,000 gallon water tank and a 16 ton coal bunker.

The RF&P retired these locomotives in 1950 and there are no surviving examples.

Class Details by Steve Llanso of Sweat House Media

Class 501 (Locobase 221)

Data from 1937 RF & P locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Delivered in pairs in 1924 & 1925 with boilers pressing 200 psi, but later increased to 225 psi. Firebox heating surface included 95 sq ft of syphons, 16 sq ft of arch tubes.

They lasted until 1950.

Specifications by Steve Llanso of Sweat House Media
Locobase ID221
RailroadRichmond, Fredericksburg & Potomac (RF&P)
Number in Class4
Road Numbers501-504
Number Built4
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft)20
Engine Wheelbase (ft)42.17
Ratio of driving wheelbase to overall engine wheebase 0.47
Overall Wheelbase (engine & tender) (ft)81.75
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)262,000
Engine Weight (lbs)381,000
Tender Loaded Weight (lbs)201,600
Total Engine and Tender Weight (lbs)582,600
Tender Water Capacity (gals)10,000
Tender Fuel Capacity (oil/coal) (gals/tons)16
Minimum weight of rail (calculated) (lb/yd)109
Geometry Relating to Tractive Effort
Driver Diameter (in)73
Boiler Pressure (psi)225
High Pressure Cylinders (dia x stroke) (in)28" x 30"
Tractive Effort (lbs)61,619
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.25
Heating Ability
Firebox Area (sq ft)465
Grate Area (sq ft)75
Evaporative Heating Surface (sq ft)4762
Superheating Surface (sq ft)1190
Combined Heating Surface (sq ft)5952
Evaporative Heating Surface/Cylinder Volume222.73
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation16,875
Same as above plus superheater percentage20,250
Same as above but substitute firebox area for grate area125,550
Power L122,787
Power MT766.97



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