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Oa Class
CLASS  Oa    2-8-0

Introduced: 1894 Number in Class:  1

Oa Class Register

Locomotive Specifications

  Baldwin Locomotive Works, Philadelphia, USA

Engine Weight:    
38.4 tons
Tender Weight:    19.0 tons Total Weight:    57.4 tons Adhesive Weight:    
33.7 tons
Length over Buffers:    
51' 8"
Total Wheelbase:    43' 7" Engine Wheelbase:    19' 2" Coupled Wheelbase:    
12' 3"
Tender Wheelbase:    
12' 9"
Driver Wheel Dia.:     43" Cylinders HP:    
Two - 11" x 20"
Cylinders LP:    
Two - 18" x 20"
Grate Area:    16.7 sq ft Evaporative Area:    
1056 sq ft
Superheated Area:     Working Pressure:    
180 psig
Tractive Effort:    
13600 lbs f
Coal Capacity:    3.2 tons Oil Capacity:     Water Capacity:    
1300 gals

Remarks:     Ordered by the Wellington and Nanawatu Railway Compnay this locomotive was the first narrow-gauge engine in the world to employ Samuel Vauclain's system of compounding. In this sytem the locomotive was fitted with two superimposed cylinders on each side, a high-pressure and a low-pressure sylinder being cast as a single unit and arranged so that both pistons were coupled to a single cross-head. On a standard gauge locomotive the large low-pressure cylinder was the lower of the two, but for low-slung narrow-gauge locomotives it was customary to reverse the order so that the smaller high-pressure cylinder would provide greater clearance from platforms and other obstructions near the ground. Ex WMRC #13