The DH class were built by Walkers Ltd. in 1966. The first prototype emerged from the factory numbered W1 as a demonstrator unit which was loaned to QR for a while.

The DH class was quite successful at shunting in yards, and also have been used to haul short freights on lightly laid lines such as the Mareeba – Forsayth section. They were an asset during flood times as they could operate in 2′ high waters, whereas Diesel-electrics can’t move through 200mm of water. The DHs were grossly underpowered though and they were quickly superseded in the 80s by the 60-ton Diesel Electrics of the 1700/1720 and 1620 class.

Unfortunately only 2 of the DH class remain in service with QR, DH 72 and 73. These locos are usually used for shunting electric locos at Callemondah and Mackay Depots.

The majority of the DH’s have been regauged and rebuilt into heavy cane locos. A few have been preserved by heritage groups; they are DH 14, 2, 38, 59. DH 2 is at Ipswich Workshops with QR Heritage, DH 14 is with the Ghan Preservation Society at Alice Springs, DH 38 is at Rosewood, and DH 59 is at the Puffing Billy.