World War II was a major setback for Western Australia's railway system.

During the war years only 13 new locomotives were built, three S class and 10 Australian Standard Garratts.

By 1944, approximately a quarter of the WAGR's locomotive fleet was out of action pending maintenance.

They were also used as bank engines on the steeply graded Midland Junction to Chidlow section of the Eastern Railway.

The first was withdrawn in 1968, with the remainder in 1970/71 following the entry into service of the ADK/ADB class diesel multiple units.