NZR BA Class - Construction and Later Enhancements

Construction and Later Enhancements

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.

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 and they could generate 21,200 lbf. On straight, flat track, they could haul 700-750 tons, and on the arduous steep section of the Main South Line north of Dunedin they were capable of hauling 270 tons, 50 tons more than the five locomotives that were not upgraded.

In their later years, 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.