NZR Ba class
BA 552 at Mainline Steam's Parnell depot
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| Type and origin | |
|---|---|
| Power type | Steam |
| Builder | NZR Addington Workshops |
| Build date | 1911 - 1913 |
| Specifications | |
|---|---|
| Configuration: |
|
| • Whyte | 4-8-0 |
| Gauge | 3 ft 6 in (1,067 mm) |
| Driver dia. | 42.5 in (1,080 mm) |
| Length | 52 ft 3 in (15.93 m) |
| Adhesive weight | 32.3 long tons (32.8 t) |
| Loco weight | 43.9 long tons (44.6 t; 49.2 short tons) |
| Tender weight | 25.5 long tons (25.9 t; 28.6 short tons) |
| Total weight | 69.4 long tons (70.5 t; 77.7 short tons) |
| Fuel type | Coal |
| Fuel capacity | 4.0 long tons (4.1 t; 4.5 short tons) |
| Water cap | 1,700 imp gal (7,700 l; 2,000 US gal) |
| Firebox: • Firegrate area |
16.7 square feet (1.55 m2) original 26.4 square feet (2.45 m2) rebuild |
| Boiler pressure | 175 psi (1,210 kPa) original 200 psi (1,400 kPa) rebuild |
| Superheater: |
|
| • Heating area | 206 square feet (19.1 m2) |
| Cylinders | Two |
| Cylinder size | 16 in × 22 in (406 mm × 559 mm) |
| Performance figures | |
|---|---|
| Maximum speed | 30 mph (48 km/h) |
| Tractive effort | 18,550 lbf (82,500 N) original 21,200 lbf (94,000 N) rebuild |
| Career | |
|---|---|
| Number in class | 10 |
| Numbers | 148, 497 - 500, 551 - 555 |
| Locale | Otago and Southland |
| First run | November 1911 |
| Last run | June 1969 |
| Preserved | One (BA 552) |
| Disposition | One preserved, remainder scrapped |
The BA class was a class of steam locomotive built by the New Zealand Railways Department (NZR) for use on New Zealand's national rail network. The first BA entered service in November 1911, with the last of the 11 class members introduced on 14 May 1913.
In design and appearance the BA class was very similar to the B class of 1899-1903, but superheated and with a smaller firebox. They were designed primarily for use on freight trains in the South Island, and were capable of hauling a load of goods at speeds up to 30 mph (48 km/h).
In March 1928, BA 552 was modified to have a wider firebox, and later that year the same work was done on BA 498. It was almost two decades before the alterations were performed on any other members of the class: BA 553 was done in May 1948, BA 148 the next month, and fifth and last was BA 499 in November 1949. The other BA locomotives were left with unmodified fireboxes.
The upgraded engines were capable of producing more power: their boiler pressure was raised to 200 psi (1,379 kPa) and they could generate 21,200 lbf (94 kN). On straight, flat track, they could haul 700–750 long tons (784–840 short tons; 711–762 t), and on the arduous Mihiwaka Bank north of Dunedin they were capable of hauling 270 long tons (302 short tons; 274 t), 50 long tons (56 short tons; 51 t) more than the five locomotives that were not upgraded.
Like many classes of specialised freight engines on NZR, eight of the ten BA locomotives were modified to perform shunting duties. This included an all-weather cab fixture on the tender to provide shelter for crews, and second sand domes.
The locomotives occasionally hauled suburban passenger trains in Dunedin, but were primarily freight locomotives. They operated in Otago and Southland on the Main South Line and the many branch lines that fanned from it in the first half of the 20th century. The enhanced locomotives with larger fireboxes were often seen on the Otago Central Railway.
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Wikipedia