[1] Per Queensland Railway's classification system they were designated the BB18¼ class, BB representing they had three driving axles, and the 18¼ the cylinder diameter in inches.

The extremities of that availability when they were introduced were (from Brisbane) Roma, Wallan-garra, Merinda (near Bowen), plus branches Bundamba to 3 miles 8 chains (on loop to Redbank), Gowrie to Wyreema loop, Warwick to Thane (South-Western Line), Ipswich to Workshops Gate, South Brisbane to Lota, Kuraby and Corinda, Shorncliffe, Dayboro, Pinkenba, Kilcoy, Brooloo, Byellee (near Gladstone) to Monto and Selene, Bajool to Pt Alma, Rockhampton to Emerald, Dawson and Callide Valley Branches, Townsville to Charters Towers and Babinda, and Merinda to Collinsville.

They were attached to Mayne (Brisbane), Ipswich, Toowoomba, Maryborough, Rockhampton, Mackay and Townsville depots over the years (see J W Knowles, Queensland Railways Steam Locomotives 1900 - 1960, self published, 2002, Appendix 6, p315, Line Standards).

They did the same work throughout their lives as the earlier B18 1/4, even at the beginning being seen on goods, mixed, suburban and long distance passenger trains.

Engines constructed by Walkers Limited used electricity for the light on the rear of the tender, for side lamps and to illuminate the motion.