|At the time of their appearance in service the modernised “Ba’s” were undoubtedly
the most massive-looking locomotives in the South Island, although their total
weight fell short of either the “A” or “Ab” class “Pacifics”.
Because of the increased height of the boiler it was necessary to fit squat boiler
mountings, including the Great Central type of funnel favoured by C. S. Lynde.
At first only one sand dome was fitted, but at a later stage, when a cab was provided
on the tender for added protection from the weather in shunting service, a second
sand dome was added.
The rebuilt “Ba’s”—three more were equipped with large boilers in 1948 and 1949—were
always Otago engines. They were seen in service on various branch lines, including
the Otago Central, and in later days used chiefly for shunting at Dunedin and
for short-distance freight haulage in the Dunedin industrial area. Some were transferred
Rated to haul 700-750 tons on the level, a wide-firebox “Ba” could surmount the
notorious Mihiwaka Bank (north of Dunedin) with 270 tons—50 tons better than one
of the other members of the class fitted with a narrow-firebox boiler.
In March 1928 No. 552 was rebuilt, this time with a high-pitched wide-firebox
boiler. The modifications allowed it to haul heavier mainline trains. Much of
this locomotive’s work was on the Otago Central line, and it was derailed on one
of the many tight curves soon after rebuilding. In November 1947, Ba552 was fitted
with an all-weather cab, rear cowcatcher, and additional sand dome thus equipping
the locomotive for shunting work, and it spent some time on the West Coast between
1957 and 1961. In 1964 it was given a full ‘A’ grade overhaul, receiving another
wide-firebox boiler. No.552 was used on railfan excursions between Dunedin and
Waitati on two occasions, in December 1964 and March 1967. Through 1968 and until
June 1969, it was retained for standby purposes, but was then withdrawn from service.
Mr L. J. Hostick pressed for the preservation of Ba552, and used it on another
excursion, this time to Mosgiel in November 1969. In September 1970 it featured
on a steam delivery trip between Palmerston North and Frankton, assisting A423.
Ba552 thus became the only member of the class to work in the North Island, and
for the greater part of the journey was the lead locomotive ahead of A423.