Data from John Garner's comprehensive site at [] ... (October 2002; last accessed 21 June 2025). See also Charles Rous-Marten, "The New Zealand Railways 3 ft 6 in Gauge-Their Progress and Results for 1884-Their Locomotive Practice, and New Departures in that Department", No 24575, English Mechanic and World of Science, No. 1,063 (7 August 1885), pp. 499-500.
Avonside produced six (works numbers 1038-1043 in 1874),
Dubs four (works numbers 1212-1215 in 1879)
Neilson five (works numbers were 2460-2064 in 1879)
Robert Stephenson & Company five (2367-2371 in 1879), and
Vulcan Foundry twelve (works numbers 998-1007, 1009, and 1076 in 1883.)
Garner said tha these engines held two distinctions: they were the first New Zealand tender engines, and they were the only Moguls ever bought for the islands. Photos show a tall stack, sand boxes ahead and behind the slightly taller steam dome. The rear sand box sat on top of the Belpaire firebox. As small as the drivers were already, the running board included small splasher over the top portion of the first two drivers on each side.
Rous-Marten, then with the NZR, noted that the majority of service that then constituted main line traffic were slow-speed mixed trains. He described their occasional runs on the Christchurch-Dunedin service as consisting of "slow expresses for 140 miles [225 km] and fast stopping-trains over 90 miles [145 km]." J-class engines averaged 30 mph (48 kph) over an alignment that included one in 100 (1%) gradients in both directions between Studholme Junction and Oxmarn
As with many of New Zealand's 19th Century engines, the Js could not handle the heavier trains that handled greater demand. Four were later modified as W-class 2-6-2Ts (Locobase 5187) and 11 others became Wa-class switchers (Locobase 5188)..
Four early Vulcans left the roster in 1919, eight more locomotives followed in 1927-1929, and the remainder closed the class in the early 1930s.
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | J |
| Locobase ID | 5174 |
| Railroad | New Zealand Railways |
| Country | New Zealand |
| Whyte | 2-6-0 |
| Number in Class | 32 |
| Road Numbers | 14-15,26,59,61,70,81-86,110, 115-24,234-36,258-63 |
| Gauge | 3'6" |
| Number Built | 32 |
| Builder | several |
| Year | 1874 |
| Valve Gear | Stephenson |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 9 / 2.74 |
| Engine Wheelbase (ft / m) | 15.83 / 4.82 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.57 |
| Overall Wheelbase (engine & tender) (ft / m) | 33.45 / 10.20 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | |
| Weight on Drivers (lbs / kg) | 39,200 / 17,781 |
| Engine Weight (lbs / kg) | 47,040 / 21,337 |
| Tender Loaded Weight (lbs / kg) | 38,080 / 17,273 |
| Total Engine and Tender Weight (lbs / kg) | 85,120 / 38,610 |
| Tender Water Capacity (gals / ML) | 360 / 1.36 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 0.60 / 1 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 22 / 11 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 42 / 1067 |
| Boiler Pressure (psi / kPa) | 130 / 900 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 14" x 20" / 356x508 |
| Tractive Effort (lbs / kg) | 10,313 / 4677.90 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.80 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | |
| Firebox Area (sq ft / m2) | 57 / 5.30 |
| Grate Area (sq ft / m2) | 12 / 1.12 |
| Evaporative Heating Surface (sq ft / m2) | 686 / 63.75 |
| Superheating Surface (sq ft / m2) | |
| Combined Heating Surface (sq ft / m2) | 686 / 63.75 |
| Evaporative Heating Surface/Cylinder Volume | 192.51 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 1560 |
| Same as above plus superheater percentage | 1560 |
| Same as above but substitute firebox area for grate area | 7410 |
| Power L1 | 2480 |
| Power MT | 418.43 |