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Q Class
CLASS  Q    4-6-2

Introduced: 1901 Number in Class: 13

Q Class Register

Locomotive Specifications

  Baldwin LocomotiveWorks, Philadelphia, USA

Engine Weight:    
48.0 tons
Tender Weight:    
24.1 tons
Total Weight:    72.1 tons Adhesive Weight:    
30.7 tons
Length over Buffers:    
55' 4"
Total Wheelbase:     48' 3 3/4" Engine Wheelbase:    26' 3" Coupled Wheelbase:    
9' 2"
Tender Wheelbase:    
12' 4"
Driver Wheel Dia.:    49 1/8" Cylinders HP:    
Two - 16" x 22"
Cylinders LP:    
Grate Area:    40.0 sq ft Evaporative Area:    
1683 sq ft
Superheated Area:     Working Pressure:    
200 psig
Tractive Effort:    
18340 lbs f
Coal Capacity:    5.0 tons Oil Capacity:     Water Capacity:    
1700 gals

Remarks:     The 'Q' was the first locomotive to which the generic type name 'Pacific' was applied, this wheel arrangement quickly became extremely popular worldwide. Designed to burn Otago lignite coal, they employed wide Wooten fireboxes supported by a two-wheeled trailing truck. The 'Q' was used on express trains on the Auckland-Rotorua , and Oamaru-Dunedin sections, but were restricted by the use of light rails until they could be replaced with heavier material. They performed well until traffic demands forced them to give way to more powerful Pacifics. The leading bogie of this class, was prone to derailment at speed and this deficiency was remedied by the fitting of a cast-iron ballast blockon the frame in front of the smokebox.