Being highly capable, the AB class were used for both freight and passenger trains. The AB class was easily able to pull an express passenger train at speeds of , or haul 700-tonne goods trains on easy grades. Along with the earlier F class, they were known as the "Maids for all work". Their work on express passenger trains was diminished by the arrival of the J class of 1939, and K class of 1932 tender locomotives in the 1930s, and also with the introduction of the heavier steel-panelled carriages built from 1930 until 1943. Despite being displaced, the AB class could still be found at work on relief expresses during holiday periods.