New Zealand DF class locomotive (1979)

Design

The DFs were powered by an EMD 12-645 engine, the same prime mover chosen for the DC class, but were able to make greater use of that power by having six traction motors and Co-Co arrangement as opposed to the four traction motors and A1A-A1A wheel arrangement of the DCs. This gave the DF several advantages: a tractive effort of 198 kN (45,000 lb_f) and a maximum speed of 113 km/h (70 mph), compared to the DCs 140 kN (31,000 lb_f) and 90–100 km/h (56–62 mph). The most noticeable visual difference between the DF and the DC is that the DF is considerably longer with the headlight arrangement on the cabs differing: the DC has the lights arranged horizontally, while the DF has them arranged vertically. The DF is more often confused with the DX class, as both are of similar dimensions though the DX also has the horizontal headlight arrangement.

History

The first 20 members of the DF class arrived in New Zealand in 1979, and initially ten worked on the East Coast Main Trunk, Kinleith, Rotorua and Murupara Branches, making use of the recently opened Kaimai Tunnel; and ten worked freight trains on the Main North Line between Christchurch and Picton. At the time, they were the most powerful locomotives in the South Island, with a total power output of 1,230 kilowatts (1,650 hp).

The next ten DFs arrived in 1981 and were also sent to work in the Bay of Plenty, and some to supplement the South Island fleet, which by this time had also entered service on the Main South Line and Midland Line as far as Arthur's Pass.

In 1986 the DF fleet was reallocated, concentrating 22 of the class in the South Island, and reallocating the remaining eight North Island DFs from Hamilton to Wellington, for use between Wellington and Gisborne, on the Wairarapa Line and Palmerston North - Gisborne Line (PNGL).

In 1988, the fleet was again reallocated due to the opening of the NIMT electrification, with approximately 20 DFs based in Auckland for use in Northland, and between Auckland, Hamilton and the ECMT and its branches. The remaining units were based in the South Island. This removed the DFs from the lower North Island - Gisborne routes, and reduced the number in the South Island.

Rebuilding to DFT

The main downside to the DF was the lack of power output from the diesel engine. This hindered the DF when it came to hauling heavy freight trains out of multiple.

In 1992, DF 6260 was rebuilt with a new turbocharged diesel engine and some other minor alterations. The rebuilt DF was reclassified DFT (the T standing for turbocharged), and renumbered 7008.

After 18 months of trial, the decision was made to convert the remaining 29 DFs to DFTs, with the last unit converted in 1997. The turbocharged locos can now generate 1,800 kW (2,400 hp), and now comfortably fits between the DC class and the DX class in terms of power output.

Current

The class remains predominantly employed on general freight duties on all routes nationwide, with the general exception of through trains on the NIMT and the Midland Line coal workings. The units operate both in multiple with the other mainline locomotive classes, or as single units, depending on availability and the level of motive power required. Since October 2016, DFBs that are fitted with an fire suppression system, have been assigned to all the North Island KiwiRail Scenic Journeys passenger services, but they are occasionally used on the Coastal Pacific in the South Island.

Auckland Transport service

Three DFTs/DFBs were in service in Auckland hauling six-car SA trains on the Auckland suburban network, leased by Auckland Transport. These trains were made up of ex-British Rail Mark 2 carriages, rebuilt for use on Auckland commuter trains. Most were in four- or five-car configurations with a DC class locomotive. The locomotives used on 6-car SA sets were DFBs 7010, 7200 and 7348, and DFT 7104. These began service on 20 September 2010 with the introduction of a new timetable. DFB 7010 was released back to KiwiRail in November 2012 leaving three units operating. Other DFTs have been assigned periodically to cover for when these units undergo maintenance, with DFT 7051 and DFB 7186 most recently filling this role during the 2011 Rugby World Cup when extra six-car trains were in use.

Wairarapa Connection service

Since July 2015, up to five DFB locomotives have been the main motive power on the Wairarapa Connection passenger service and Masterton to Wellington freight services, replacing six of DC class that were used on the service since mid-2014. The units assigned on the service were taken to Hutt Workshops to be fitted with a fire suppression. In July 2016, Transdev Wellington took over operation of the Wairarapa Connection service, with KiwiRail still providing and operating the DFB locomotives on a "hook-and-tow" basis. From October 2016, any fire suppressed DFBs that are mainly kept around the Wellington Region, can be used on the service.

Numbering

In common with NZR practice at the time the class was numbered with reference to the power output (1,650 hp), with the first 20 units numbered 1651 to 1670. With the introduction of the TMS system in 1980 these locomotives were renumbered in order with new four digit numbers starting with 6 in which the last number acted as a check number; DF 1651 became DF 6006 and DF 1670 becoming DF 6202. The second batch all received TMS numbers while under construction. They were then renumbered again when rebuilt to DFT standard in the 7xxx series, with these numbers allocated as they were rebuilt with no reference to their previous number.

Vision upgrades

Prior to the rebuilding to DFT standard, the locomotives received an upgrade in the late 1980s with the introduction of single-manning to improve visibility for the driver; this involved a large single front window replacing the original configuration that had two small windows instead.

In the late 1990s the driver's side front window was enlarged to prevent eye and back problems for drivers focusing on the mainline ahead. The pillar separating the driver's window and the central window created a potentially dangerous blind spot and caused a distraction for drivers as their vision had to adjust to focus, or alternatively adopt unnatural sitting positions. Drivers started to notice left-eye fatigue and back issues after long shifts or extended periods driving the locomotives. The pillar was moved 100mm to the left with the top and bottom sills was raised and lowered at the same time to give drivers a better view of the track immediately in front and below. Fewer issues have been reported since.

Livery

Since the DFs were introduced in the International Orange or "Fruit Salad" livery – orange long-hood, grey cab, and yellow ends with large white numbers on the long hood, which was the standard livery for NZ Railways until the late 1980s, they have been repainted in several liveries since:

In addition, DF 6133 was one of two locomotives to wear the Tasman Forestry livery, with brown long-hood and cab with yellow ends.

Ownership

In December 1996, Tranz Rail sold the DFT class to the General American Transportation Corporation (GATX, an American locomotive and rolling stock leasing company) for $131.5 million. It then leased the locomotives back for a period of 12 years. The lease ended on 19 December 2008 with ownership of the locomotives going to Tranz Rail's successor, KiwiRail, which paid a further $36.6m to buy the locomotives back.

Sub-classes

In the early 2000s a number of DFTs were fitted with the Maxitrax wheelslip control and received an internal sub-classification of DFM. This was used in the Amicus computer system only, and the classification was initially not applied to the locomotives themselves which remained identified as DFT. Although Maxitrax has since been removed from these locomotives the units some of the units that were classed as DFM have had the designation applied to them when repainted into the KiwiRail livery.

Between 2006/07, Toll Rail installed the Brightstar engine management system into twelve DFT class locomotives, with these locomotives then officially reclassified as DFB. In June 2016, KiwiRail re-introduced the programme for a number of DFTs that were stored at Hutt Workshops. As of 000000002017-02-01-0000February 2017, four of these locomotives are being converted and are undergoing the current "DFB overhaul" programme.

Withdrawals

DFT 7117 was withdrawn in July 2011 following an accident north of Kaikoura a month earlier. It is stored at Hutt Workshops and has been used as a source of spare parts for the other locomotives. It was believed that the other 17 remaining DFTs would be withdrawn after the second batch of DLs arrive, owing to the decision to refurbish only the 12 DFB locomotives. However, despite the second 20 DLs now being in service, a total of twelve (including 7117) were withdrawn.

7008 and 7132 were returned to service after receiving repairs in late 2015/early 2016. In May 2016 KiwiRail confirmed that at least three withdrawn DFTs were candidates for DFB conversion and that 7104 was being reinstated. In June it was revealed some withdrawn DFTs would indeed be converted to DFBs with the option of the remaining DFT fleet being converted in the near future. They will be fitted with Brightstar and undergo the 'DFB overhaul' program on reinstatement. The first of these have already begun with 7282 starting on 28 June 2016. Currently four units are now being converted and fully overhauled.

Accidents

A number of DF class locomotives have been involved in derailments and level crossing accidents that have required repair. The most significant incident involving a DF unit was a head-on collision between DFT 7254 and DC 4202 and DX 5448 at Waipahi in Otago on 20 October 1999, in which the driver of the DFT was killed and the locomotive suffered considerable frontal damage. After a lengthy period in storage, it was fully rebuilt and returned to service renumbered as DFB 7348.

In popular culture