After 1929, railmotors that provided the service were built on bus and truck chassis of the Associated Equipment Company (AEC). Buses in London had been built on the same type 506 chassis since 1914. Thirty-eight of the chassis were imported into Queensland from 1927-31, and fitted out with seats and bodies, and converted for rail use.
RM31: 45 horsepower AEC, built at Ipswich Railway Workshops 1928, in service Normanton Croydon railway 1929-1945.
RM32: 45 horsepower AEC, built Ipswich Railway Workshops 1929, in service Normanton-Croydon railway 1945-1960.
RM60: 45 horsepower AEC, built Ipswich Railway Workshops 1931, in service Normanton-Croydon railway, 1960-1964.
RM74: 100 horsepower AEC railmotor, built Ipswich Railway Workshops 1934, converted in 1942 to 102 horsepower Gardner diesel engine, in service Normanton-Croydon railway 1964-1982.