NZR DG Class - Introduction

Introduction

Due a change in government dieselisation strategy 21 of the original order for DF class were changed to 42 DG class locomotives, being a 'half' version of the DF with only one cab instead of two, and a similar Bulldog nose. The English Electric Co, as they did with many of their diesel locomotives of the 1950s-60s, did not assemble them at the Preston works, but allocated the final assembly of build numbers 2254/E7821-2273/E7840 (road no. 750-769) to Robert Stephenson & Hawthorn and build numbers 2274/D353-2295/D374 (road no. 770-791) to Vulcan Foundry, both English Electric plants. The South Island allocated locomotives were initially classified DH because they were fitted with adjustable bogies that allowed a higher maximum axle weight and tractive effort.

The first regular outing by a DG class locomotive was that of DG 750 in August 1955 when it was sent with 'Twin-set' railcar RM 100, a EE DF class locomotive, and a newly-arrived Drewry DSB class shunting locomotive to the Wanganui Industrial Fair. Shortly after the class took over workings in the Wairarapa area following the completion of the Rimutaka Tunnel and also the Murupara Branch from the older DE class. These locomotives usually worked in multiple as they were relatively low-powered, although they did occasionally run on their own.

With the arrival of enough DA class locomotives in the North Island, the DG locomotives from the North Island were transferred progressively south with the introduction of the Aramoana rail ferry in 1962. As a result, the DH class locomotives were converted to DG class standards in 1968 and received the DG classification, allowing the DH classification to be re-used in 1978.

With the introduction of the DJ class in 1968 the class was usually relegated to "slave" status. The introduction of the new DF class further displaced the class.