The New Zealand DC class locomotive is a type of diesel-electric mainline locomotive on the New Zealand rail network, operated by KiwiRail on freight trains, and formerly on long-distance passenger trains. The class was rebuilt from the DA class in the late 1970s and early 1980s, mainly in Australia. After the DA class, they were the most numerous class of diesel locomotive on New Zealand's railway network and remained numerically dominant until the mid-2010s when withdrawals began.
History
The locomotives were introduced as the Phase III units of the DA class, built by General Motors Canada between 1961 and 1967. Between 1978 and 1983, 85 of the later-build DAs were rebuilt.
Because of a backlog of locomotives requiring heavy maintenance, Clyde Engineering were awarded a contract to rebuild 35 DA class as EMD model G22ARs, with upgraded engines, new cabs and low short hoods of a style similar to the DX class introduced earlier in the 1970s and the DF class being introduced at the time. The first few were shipped directly to Port Adelaide, but after the Union Company withdrew its roll-on/roll-off services, most were shipped to Melbourne's Appleton Dock and hauled to Adelaide via the Victorian and South Australian lines.
Further contract extensions resulted in a total of 80 being rebuilt by Clyde Engineering. A further five were rebuilt at the Hutt Workshops near Wellington, but retained their existing engines.
Technical details
Each locomotive has a General Motors 12-645C or 12-645E V12 diesel engine (the same as originally fitted to the DF class) and four traction motors, with an authorised maximum speed of 100 km/h. They are 14 metres long, 3.8 metres high and weigh 82 tonnes. They can be readily identified as they are considerably shorter than the DF and DX classes and have their paired headlights arranged horizontally, rather than vertically on the DFs.
The five 49-series Hutt-built DCs originally retained the 12-567 engine, before later receiving the 12-645.
In service
History
The class was initially employed in the North Island, mainly on freight trains but also hauling either carriage trains or AC class Grassgrub depowered railcars.
Changes came during the 1980s; the deregulation of land transport saw rail freight volumes decline and the opening of the North Island Main Trunk electrification saw the locomotive fleet reallocated. These factors saw the withdrawal between 1985 and 1989 of the DJ class and remaining DA class, with the DC class also seeing service in the South Island for the first time. The locomotives were also used on export coal trains between the West Coast and Christchurch.
The class were used on KiwiRail Scenic's South Island Coastal Pacific, and was also used on the North Island’s Northern Explorer until being replaced by a DFB/T, DXB or occasionally a DXC unit and on the TranzAlpine until being replaced by two DXC locomotives. A DC class locomotive is also occasionally employed to haul the Capital Connection service.
The Northern Explorer's predecessor, the Overlander, was usually hauled on the northern and southern sections of the North Island Main Trunk by a DC class locomotive, and was often used across the central section as well if an EF locomotive was unavailable.
Cab concerns
In March 2001, the Rail & Maritime Transport Union threatened to set the maximum speed of the DC class to 50 kilometres per hour due to corrosion found on cab mounts. This causes the cab of a DC to detach from the frame during a derailment, and a driver had fallen through the floor of a unit. An audit was made on all units and found 19 locomotives had maintenance concerns. The concerned units were relegated to trail-only units, and work was made in a short matter of time to repair the cabs. It was understood the concerned units would be fitted with universal cabs, but this never commenced.
In early 2017, concerns were raised by the RMTU surrounding rusty cab structures, cab mounting, and anti-collision posts. Fearing the cabs could have been ripped off in the course of an accident, all (but one) units were banned from leading in the South Island; again confined to trail-only units until they had been inspected. Although units in the North Island were banned from leading trains, they were seen being used on shunts. Work was carried out at both Hutt and Hillside workshops, most were back leading trains within a couple of months.