THE AUSTRALIAN SUGAR industry has more than 50 DH and 73 Class ex- Government nominal 40 tonne locomotives in operation. The first of these locomotives began service after conversion to cane field specification in 1991. At the time, the conversion of these shunting locomotives was an effective strategy to realise additional capacity in a short time frame. It was understood that a compromise with this strategy was that there was no transmission ‘lock-up’ function with the Voith transmission supplied with these locomotives, whereas cane haul duty requires ‘lock-up’ for fuel efficiency. This compromise was acceptable while the Voith transmission was reliable but the transmissions are now no longer reliable. This issue has provided an opportunity to re-design the drivelines for these locomotives to be better matched to cane field duty and thereby realise significant savings in fuel burn and improved locomotive reliability. The Voith transmission is being replaced with an Allison 4000 Series retarder model transmission coupled to a Renk-Maag vertical offset reversing transmission. The re-designed transmission can now achieve an efficiency of up to 96%, which compares with the Voith transmission highest efficiency of around 60%. The improvement in transmission efficiency has allowed the diesel engine to be downsized from a twelve cylinder 23.9 L engine to an eight cylinder 15.9 L engine (33% reduction in engine displacement). Any improvement in the 40 tonne locomotive efficiency is significant for the Australian sugar industry, as these locomotives account for more than 50% of the industry cane haul capacity. The potential for up to 15% locomotive fuel savings for the Queensland sugar industry when this project is fully implemented, combined with reduced whole life costing, is of great interest to cane transport system operators, as is the reduction in exhaust emissions combined with an expected lower radiated noise from the power module. The prototype repower is currently being installed in the locomotive ‘Piralko’ to begin operation in the 2017 season. A replacement program has been scheduled for the remaining 23 of Wilmar’s 40 tonne locomotives, following the successful installation and testing of the prototype.