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A Class 4-6-2
CLASS  A/Ad    4-6-2

Introduced: 1906 Number in Class: 58

A Class Register



Ad Class (until 1916)

Locomotive Specifications

  1.   NZR Addington (8)
  2.   A & G Price Ltd. Thames (50)

Engine Weight:    
51.0 tons
Tender Weight:    25.5 tons Total Weight:    
76.5 tons
Adhesive Weight:    
33.1 tons
Length over Buffers:    
57' 2"
Total Wheelbase:    48' 9 5/8" Engine Wheelbase:    27' 1" Coupled Wheelbase:    
10' 0"
Tender Wheelbase:    
12' 8"
Driver Wheel Dia.:    54" Cylinders HP:    
Two - 12" x 22"
Cylinders LP:    
Two - 19" x 22"
Grate Area:    30.0 sq ft Evaporative Area:    
1724 sq ft
Superheated Area:     Working Pressure:    
225 psig
Tractive Effort:    
17000 lbs f
Coal Capacity:    4.0 tons Oil Capacity:     Water Capacity:    
1700 gals

Remarks:     At the time considered to be the most handsome locomotive ever to run on New Zealand rails, this design was a four cylinder de Glehn balanced compound. The first four locomotives had Stephenson link motion to actuate the valves of the inside cylinders, with Walschearts motion for the outer cylinders. All others had Walschearts gear throughout.

Thirty locomotives built by A. & G. Price were originally classified Ad to distinguish them from the Addington locomotives, having a new live steam supply to the low pressure cylinders, plus several other small differences. Outwardly they had a rectangular front beam, an acetylene headlamp, and a 'Capuchon' funnel having a distinctive extra rim on the front of the funnel, although these were later removed.

Because the compounds were significantly more costly to maintain, the decision was taken that 57 of these locomotives be rebuilt as two cylinder simple engines between 1941 - 1949. One more, No. 409 was built new as a simple engine in 19078. Conversion to simple expansion made it possible to reduce the working pressure from 225 lb to 190 lb sq in, but the tractive effort was increased from 17,000 lb to 20,064 lb. Thus the simple 'A' was the equivalent, for traffic purposes, to an 'Ab', and was rated to haul the same loads.

Preserved Locomotives
  Glenbrook Vintage Railway,    Glenbrook -     A 423,     A&G Price #26/1909   Stored
  Weka Pass Railway,    Waipara -     A 428,     A&G Price #31/1909   Operating