The final duties of the AB class were on branch line workings, where they found their niche after being displaced from most mainline duties by larger locomotives. These in turn displaced the A and Q class 4-6-2 locomotives from their duties, resulting in the withdrawal of all Q class locomotives by 1957 and a reduction in the number of A class locomotives. The locomotives also worked some lesser mainline duties, and others, such as those at Gisborne, were used as bankers to assist trains heading south to Napier.