St Louis-San Francisco 4-8-4 "Northern" Type Locomotives

Class 4500 (Locobase 277)

Based on the CB&Q's O-5 Northern design. Baldwin produced the first batch in August 1942 (works 64437-64451)

Firebox heating surface included 137 sq ft in 3 thermic syphons. The first 3 engines -- 4500-4502 -- were oil-fired and used for passenger service. They were painted blue and white with red letters proclaiming their duty as pulling the Meteor.

The other 12 in the first batch -- 4503 to 4514 -- used coal fuel and pulled freight. Boiler pressure and hence TE varied slightly. Ten more came from Baldwin in August 1943 (69731-69740); these were fitted with trailing-truck boosters that soon appeared on the earlier engines.

The web site for the restored 4500 gives slightly different measures for heating surfaces.

Specifications
Class4500
Locobase ID277
RailroadSt Louis-San Francisco (SLSF)
Whyte4-8-4
Road Numbers4500-4524
GaugeStd
BuilderBaldwin
Year1943
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase19.25'
Engine Wheelbase46.50'
Ratio of driving wheelbase to overall engine wheebase 0.41
Overall Wheelbase (engine & tender)
Axle Loading (Maximum Weight per Axle)70620 lbs
Weight on Drivers280000 lbs
Engine Weight462500 lbs
Tender Light Weight241300 lbs
Total Engine and Tender Weight703800 lbs
Tender Water Capacity18000 gals
Tender Fuel Capacity (oil/coal)24 tons
Minimum weight per yard of rail on which locomotive could run116.67 lb rail
Geometry Relating to Tractive Effort
Driver Diameter74"
Boiler Pressure255 psi
Cylinders (dia x stroke)28" x 31"
Tractive Effort71188 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.93
Heating Ability
Firebox Area544 sq. ft
Grate Area88 sq. ft
Evaporative Heating Surface4766
Superheating Surface1530
Combined Heating Surface6296
Evaporative Heating Surface/Cylinder Volume215.72
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation22440
Same as above plus superheater percentage27893.18
Same as above but substitute firebox area for grate area172430.55
Power L130258.56
Power MT952.98

Credits

Introduction and specifications provided by Steve Llanso of Sweat House Media.