The NZR

New Zealand Railways Department

The New Zealand Railways Department, NZR or NZGR and often known as the "Railways", was a government department charged with owning and maintaining New Zealand's railway infrastructure and operating the railway system. The Department was created in 1880 and was reformed in 1981 into the New...

 DG and DH class locomotives were a class of diesel-electric

Diesel-electric

Diesel-electric transmission or diesel-electric powertrain is used by a number of vehicle and ship types for providing locomotion.A diesel-electric transmission system includes a diesel engine connected to an electrical generator, creating electricity that powers electric traction motors...

 locomotives used on New Zealand's national rail network

Rail transport in New Zealand

Rail transport in New Zealand consists of a network of gauge railway lines in both the North and South Islands. Rail services are focused primarily on freight, particularly bulk freight, with limited passenger services on some lines...

, built by English Electric

English Electric

English Electric was a British industrial manufacturer. Founded in 1918, it initially specialised in industrial electric motors and transformers...

.

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

Bulldog nose

"Bulldog nose" is the nickname given, due to their appearance, to several diesel locomotives manufactured by GM-EMD and its licencees from 1939 to 1970...

. 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

Vulcan Foundry

Vulcan Foundry was a British locomotive builder sited at Newton-le-Willows, Lancashire .-History:It was originally opened in 1832 as Charles Tayleur and Company to produce girders for bridges, switches and crossings, and other ironwork following the opening of the Liverpool and Manchester Railway...

 both English Electric plants. The South Island

South Island

The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

 allocated locomotives were initially classified 'DH' because of their higher maximum axle weight and tractive effort. However, DG locomotives from the North Island

North Island

The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...

 began operating in the South with the introduction of the Aramoana

Aramoana (ferry)

Government Motor Vessel Aramoana was a roll-on roll-off train ferry operating across the Cook Strait between 1962 and 1983.-History:...

 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

NZR DH class

The NZR DH class is a type of diesel-electric shunting locomotive in New Zealand. The class consists of six heavy shunt U10B type loco built by General Electric in the US in 1978...

.

The DG class suffered from a number of defects, mainly relating to design deficiences in the engines and the standards of design of first-generation diesel locomotives worldwide, especially in relation to noise and crew comfort. Thus with the introduction of the DJ class

NZR DJ class

The NZR DJ class locomotive is a class of diesel-electric locomotive used in New Zealand. The class were purchased from Mitsubishi Heavy Industries with a modernisation loan from the World Bank to replace steam locomotives in the South Island, where most of the class members worked most of their...

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

NZR DF class (1979)

The NZR DF class of 1979 is a class of 30 Co-Co diesel-electric locomotives built by General Motors Diesel of Canada between 1979 and 1981. Between 1992 and 1997, all the locomotives were rebuilt as the DFT class, a turbocharged version of the DF....

 further displaced the class.

Rebuilds

In an attempt to modernise the locomotives and extend their working lives, ten members of the DG class were rebuilt by Hillside Workshops between 1978 and 1980. The main cosmetic change was to the locomotives' cabs, which were replaced with a New Zealand Railways designed structure. Engineering changes included relocation of the front traction motor blower to a position above the main generator, removal of the A7EL brake controls in favour of a hybrid New Zealand designed push button system, upgrading of traction motors and overseas welding to address cracks in engine blocks. Minor cosmetic changes included addition of steps at the rear of the locomotive for roof access, provision of external door handles and step ladders for mid-loco engine room doors and an automated handbrake system. Six of the recabbed locomotives were members of the Robert Stephenson & Hawthorn built batch. At the same time, nine of the Vulcan Foundry built batch and one of the Robert Stephenson & Hawthorn batch were overhauled to work as slaves (B units) with the recabbed locomotives; they did not receive new cabs and thus were not driven in regular service.

However, the class continued to be plagued by operational problems and were all withdrawn from service at the end of 1983, the slave units being written off first, followed by the recabs. Recab DG 2007 and original 2468 ran a farewell excursion on the Christchurch - Arthurs Pass section of the Midland line

Midland Line, New Zealand

The Midland line is a 212 km section of railway between Rolleston and Greymouth in the South Island of New Zealand. The line features five major bridges, five viaducts and 17 tunnels, the longest of which is the Otira tunnel.-Freight services:...

 on 28 August 1983. This marked the end of the old cab DG service. DG 2007 suffered major failure (con rod through engine block) during the following month. DG 2468 moved to the Weka Pass Railway soon after.

Preservation

Four locomotives have been preserved: DGs 770 and 791 at the Weka Pass Railway

Weka Pass Railway

The Weka Pass Railway is a New Zealand heritage railway based in Waipara, North Canterbury. It is operated on a 12 km length of the former Waiau Branch railway between Waipara and Waikari. The railway is operated by an incorporated society whose members come from all walks of life and are largely...

, DG 772 by the Diesel Traction Group at Ferrymead

Ferrymead Railway

The Ferrymead Railway is a New Zealand heritage railway built upon the formation of New Zealand's first public railway, the line from Ferrymead to Christchurch, which opened in 1863. On the opening of the line to Lyttelton on 9 December 1867, the Ferrymead Railway became the Ferrymead Branch and...

, and a fourth, DG 783, is owned privately and stored at Ferrymead.

Dg 772 is registered and certified for use on the National Rail Network.

Class register

Original No.	TMS No.	Introduced	Withdrawn	Status	Notes
DG 750	2007			Scrapped	Recabbed 1979.
DG 751	2474			Scrapped
DG 752	2036			Scrapped	Recabbed 1979.
DG 753	2042			Scrapped
DG 754	2059			Scrapped
DG 755	2065			Scrapped
DG 756	2071			Scrapped
DG 757	2088			Scrapped
DG 758	2094			Scrapped
DG 759	2105			Scrapped	Recabbed 1980.
DG 760	2111			Scrapped	Recabbed 1978.
DG 761	2128			Scrapped	Recabbed 1980.
DG 762	2134			Scrapped
DG 763	2140			Scrapped	Recabbed 1979.
DG 764	2157			Scrapped
DG 765	2163			Scrapped
DH 766	2186			Scrapped
DG 767	2192			Scrapped
DG 768	2480			Scrapped
DG 769	2226			Scrapped
DG 770	2232			Preserved	Weka Pass Railway Weka Pass Railway The Weka Pass Railway is a New Zealand heritage railway based in Waipara, North Canterbury. It is operated on a 12 km length of the former Waiau Branch railway between Waipara and Waikari. The railway is operated by an incorporated society whose members come from all walks of life and are largely... , Waipara Waipara Waipara is a small town in north Canterbury, on the banks of the Waipara River.It is at the junction of State Highways 1 and 7 60 kilometres north of Christchurch... .
DG 771	2249			Scrapped
DG 772	2255			Preserved	Ferrymead Railway Ferrymead Railway The Ferrymead Railway is a New Zealand heritage railway built upon the formation of New Zealand's first public railway, the line from Ferrymead to Christchurch, which opened in 1863. On the opening of the line to Lyttelton on 9 December 1867, the Ferrymead Railway became the Ferrymead Branch and... , Christchurch Christchurch Christchurch is the largest city in the South Island of New Zealand, and the country's second-largest urban area after Auckland. It lies one third of the way down the South Island's east coast, just north of Banks Peninsula which itself, since 2006, lies within the formal limits of... .
DG 773	2261			Scrapped
DG 774	2278			Scrapped
DG 775	2284			Scrapped
DG 776	2290			Scrapped	Recabbed 1980.
DH 777	2301			Scrapped
DH 778	2318			Scrapped
DH 779	2324			Scrapped
DH 780	2330			Scrapped	Recabbed 1980.
DH 781	2347			Scrapped	Recabbed 1979.
DH 782	2497			Scrapped
DH 783	2376			Preserved	Stored at Ferrymead Railway Ferrymead Railway The Ferrymead Railway is a New Zealand heritage railway built upon the formation of New Zealand's first public railway, the line from Ferrymead to Christchurch, which opened in 1863. On the opening of the line to Lyttelton on 9 December 1867, the Ferrymead Railway became the Ferrymead Branch and... .
DG 784	2382			Scrapped
DG 785	2399			Scrapped
DG 786	2416			Scrapped
DG 787	2422			Scrapped
DG 788	2439			Scrapped	Recabbed 1980.
DG 789	2445			Scrapped
DG 790	2451			Scrapped
DG 791	2468			Preserved	Weka Pass Railway Weka Pass Railway The Weka Pass Railway is a New Zealand heritage railway based in Waipara, North Canterbury. It is operated on a 12 km length of the former Waiau Branch railway between Waipara and Waikari. The railway is operated by an incorporated society whose members come from all walks of life and are largely... , Waipara Waipara Waipara is a small town in north Canterbury, on the banks of the Waipara River.It is at the junction of State Highways 1 and 7 60 kilometres north of Christchurch... .