The reference for locomotives and railcars
South Side Rapid Transit No. 1 to 46
United States | 1892 | 46 produced
Ron Ziel, „American Locomotives 1858 to 1949”

For the South Side Rapid Transit in Chicago, it was required that the trains with five four-axle passenger cars should achieve an average speed of 15 mph. This was higher than, for example, on the New York Elevated and required extra powerful Forney locomotives. Thus, in 1892 Baldwin delivered a total of 45 of these locomotives, which were primarily optimized in terms of power.

Unusual for a locomotive of this size was that they had a four-cylinder Vauclain compound engine. All cylinders could be supplied with live steam for starting, which ensured high starting tractive effort and rapid acceleration. Thanks to a large firebox, it was possible to use slow-burning anthracite, which reduced smoke emissions and simplified the crew's work.

Another locomotive with the number 46 was also built with a compound engine, but with only two larger cylinders. Since this did not prove itself as a compound machine, it was converted to simple steam expansion and used in switching service.

The performance of the locomotives was fully utilized with a timetable that had two-minute intervals at rush hour. The network was electrified as early as 1898, so the steam locomotives were sold. Many locomotives ended up in industry or logging service, where their mobility was an advantage.

Axle config0-4-4T (Forney) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Wheelbase16 ft 4 in
Fixed wheelbase5 ft
Service weight58,000 lbs
Adhesive weight40,000 lbs
Axle load20,000 lbs
Water capacity750 us gal
Fuel capacitycoal
Power sourcesteam
Estimated power300 hp (224 kW)
Optimal speed28 mph
Starting effort6,943 lbf
with start valve8,332 lbf
Power Plant
Driver diameter42 in
Boiler pressure180 psi
Expansion typecompound
Cylindersfour, HP: 9 x 16 in
and LP: 15 x 16 in
Grate area19 sq ft
Firebox area70 sq ft
Tube heating area485 sq ft
Evaporative heating area555 sq ft
Total heating area555 sq ft
Calculated Values
steam locomotive
tank locomotive
Vauclain compound
last changed: 07/2023

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