The 3100/3200 class locos were the first electric locos bought by QR for the electrification of the Bowen Basin. The locos were built by Comeng at Rocklea using Hitachi electronics.

All 84 members of the class are based at Jililan (near Sarina) and work the northern end of the coal fields.

The main difference between the 3100 class and 3200 classes is the 3100s are fitted out as command locos (with Locotrol, Air Conditioning, Stoves, etc.) while the 3200s are only meant to be used as Slave/Remote units.