Downer EDI Rail GT46C ACe

The GT46C-ACe is a model of Australian diesel-electric locomotive designed and built between 2007–present by Downer Rail at its Cardiff Locomotive Workshops using Electro-Motive Diesel components until 2014, with later units built in Muncie, Indiana.

The first units were built as the SCT class for freight operator SCT Logistics from 2007 followed by the LDP class and TT class for Pacific National, the GWA class and GWB class for Genesee & Wyoming Australia, the WH class for Whitehaven Coal, the SSR class for Southern Shorthaul Railroad, the QE class for Qube Holdings, and the MAN class for Manildra Groups.

Design
The class was a new design for Australian conditions based on other locomotives produced by Downer EDI Rail, such as the narrow gauge GT42CU AC purchased by Queensland Rail and Pacific National and the GT46C purchased by Westrail, Freight Australia and FreightLink. The GT42CU AC used a 12-cylinder EMD 710 engine, based on the US-built SD70MAC with scaled-down traction motors, while the GT46C used a 16-cylinder EMD 710 engine with DC traction systems. The American SD70ACe was EMD's second-generation AC loco with IGBT inverters, but was too large and heavy for the Australian interstate standard gauge network, weighing in at 188 tonnes when the limit was 134 tonnes. In addition, the GT46C design was already at the 134 tonne limit, even before adding inverters, heavier traction motors and more cooling capacity for the higher power engine, and there was a requirement that fuel capacity could not be sacrificed.

The locomotive has AC traction equipment, with a Mitsubishi Electric package also used on the SD70ACe, including a TA17 traction alternator, CA9E companion alternator and six ITB 2630 traction motors, along with solid state IGBT inverters. The prime mover is a turbocharged 16-cylinder EMD 710. New technology used included passive steer bogies, to reduce flange wear on curves. Until local production ceased in 2014, the class were built at Cardiff except for frames constructed at Port Augusta and bogie frames at Kelso. Locomotives were built in the US after 2014.

SCT class
The SCT class are used by SCT Logistics on their freight services from Adelaide to Melbourne, Parkes and Perth. Locomotive SCT007 is named Geoff (James Bond) Smith after the CEO of the company. The benefits of AC traction has enabled a fleet of 15 locomotives to do the work of 20 DC traction equipped locomotives, three AC vs four DC units being needed on the Melbourne to Adelaide journey, and two AC vs three DC units between Adelaide to Perth. An on-train refuelling system carries 50,000 L of diesel fuel in a tank car behind the locomotives, eliminating the need to refuel en route.

TT class and LDP class
With the ageing of the 48 and PL-class fleets, Pacific National purchased 31 TT class locomotives for Hunter Valley traffic. They are equipped with ECP brakes and are used with NHDH, NHEH and NHYH hoppers. They are different in some respects from SCT and LDP category units because they can run at two different weights. The first locomotives were originally intended to be built as LDP010-LDP018 and leased to other railway operators, until Downer EDI and Pacific National reached an agreement to sell directly. TT130, TT131 and TT132 are owned by Pacific National.

Downer built nine locomotives, LDP001 to LDP009, for their subsidiary company, Locomotive Demand Power Pty Ltd, to lease them to other freight operators. In 2018, Pacific National acquired them for coal services. Repaints of the LDP's into PN livery commenced in 2022.

WH class
Three WH class locomotives were ordered by Whitehaven Coal. Operated by Pacific National, they are used to haul coal trains from Whitehaven's mines in the Gunnedah Basin.



GWA and GWB classes
In 2011, Genesee & Wyoming Australia ordered seven locomotives (later increased to 10) for the Adelaide–Darwin rail corridor. The locomotives were used on several grain services throughout South Australia and on Genesee & Wyoming Australia intermodal services between Adelaide and Darwin.

The GWA class were accompanied by three newly commissioned GWB class (GT46C ACe Gen-II) locomotives (formerly known as EMD class) from storage in the United States. Numbered GWB101 to GWB103, they were deployed on intermodal, grain and ore traffic and were included in the sale of One Rail Australia assets to Aurizon in July 2022. A further three locomotives, numbered GWB104 to GWB106 were ordered by One Rail Australia before the sale to Aurizon took place. These locomotives arrived on Australian shores on 24 January 2023, and entered service in March of the same year.

On 14 June 2023, GWA003 and ALF21 collided with a truck near Katherine and subsequently caught fire, with both locomotives sustaining extensive damage and were subsequently scrapped.

SSR class
The 2 class members were ordered by Southern Shorthaul Railroad in 2014 to operate its grain services, displacing hired motive power. SSR ordered two more units in 2020, which were delivered in early 2024 and entered service in February 2024.

QE Class
In 2022, Qube Holdings announced that it had placed an order for 12 units to be built in the US and used on the company's new interstate intermodal rail services. The first 6 units entered service in February 2024.

CBH Group
In December 2022, CBH Group announced that it had ordered seven locomotives from Progress Rail to be delivered by November 2024 to bolster their standard-gauge locomotive fleet. They will be operated by Aurizon under the existing service agreement.

MAN Class
In April 2023, it was announced that Manildra Group had ordered 17 locomotives from Progress Rail. In an agreement similar to CBH Group's contract with Aurizon, beginning from 1 November 2024, Southern Shorthaul Railroad will provide train crews and oversee daily operation of Manildra owned locomotives and wagons. This replaces Manildra Group's existing agreement with Pacific National, who provided their own rolling stock to service Manildra Group's requirements. The locomotives are expected to be delivered by November 2024.

Related models

 * Downer EDI Rail GT46C, ancestor model
 * Downer EDI Rail GT42CU AC, narrow gauge variant
 * Downer EDI Rail GT42CU ACe, narrow gauge variant
 * UGL Rail C44aci, principal competitor