Introduced: 1915
Number in Class: 30
Bb Class as originally built
Bb Class after conversion to shunting and branch line duties
Locomotive Specifications
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| Engine Weight: 43.5 tons | Tender Weight: 25.5 tons |
Total Weight: 69.0 tons |
Adhesive Weight: 32.5 tons |
| Length over Buffers: 52' 7½" |
Total Wheelbase: 45' 2½" |
Engine Wheelbase: 22' 4" | Coupled Wheelbase: 12' 4" |
| Tender Wheelbase: 12' 8" |
Driver Wheel Dia.: 42½" | Cylinders HP: Two - 17" x 22" |
Cylinders LP: |
| Grate Area: 16.8 sq ft | Evaporative Area: 724 sq ft |
Superheated Area: 208 sq ft |
Working Pressure: 175 psig |
| Tractive Effort: 20940 lbs f |
Coal Capacity: 4.0 tons | Oil Capacity: | Water Capacity: 1700 gals |
| Remarks: Very similar to the 'Ba' class, these engines had cylinders an inch larger in diameter with a resultant increase in tractive effort from 18,500lb to 20,940lb. On level track they were rated to haul freight trains up to 700 tons. Like most engines they were also required to handle express and passenger trains where speed restrictions made it unnecessary to run faster than 35-40 m.p.h. As traffic increased and larger more powerful locomotives took over the main duties, the 'Bb' was relegated to shunting and branch line duties. With the heavier trains after the introduction of the 'K' class Locomotives, the 2-6-2 'C' class shunters could no longer handle the load. So ten of the 'Bb' class were converted to shunting engine duties and with its 4-8-0 wheel arrangement and adhesive weight of 32.5 tons with a tractive effort of 20,940 lbs force, they were successful locomotives. |
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