ZF’s eTRAC drive system offers an all-electric solution for construction machinery from 20-180 kW, including the the eCD160-210 central drive for 10-20 ton wheel loaders. Its new oil cooled e-motors ensure superior power density, best in class efficiency and performance on the same level as today’s conventional drivetrains.
For off-highway applications up to 20 tons, the central drive is expected to be the preferred technology in the market.
This topology offers a modular system and enables to reuse the same driveline installation interface as diesel engine driven vehicles.
The eTRAC electric central drive system satisfies all the expectations for performance and productivity found in traditional drivelines and combines them with the benefits and opportunities electric systems have to offer.
For vehicles like mid-sized wheel loaders, ZF developed the eTRAC eCD110 to 210 series, consisting of an electro-mechanical powershift transmission and one e-motor for traction and ePTO each. By using new oil-cooled e-motors a higher power density and better efficiency can be reached. An electric drive control unit for overall system performance and power management completes the system. With a 700 Vdc (nominally) operating voltage, the system can be scaled up to 176 kW max. power. Thanks to its modular design, the system can be integrated in various other vehicle applications as well and can be driven independently from the power source. This technology solution fits in both battery-electric vehicles and fuel-cell battery electric vehicles, which will also play a big role in the future of construction machineries.
For the central drive eCD110 to 210 series, the inverter, stator and rotor components of the e-motor as well as the clutches and gear ratio variants of the transmission have been taken from existing systems for medium-sized wheel loaders and adapted accordingly.
The reuse of proven technologies and the development of modular components play a decisive role in reducing costs and increasing the efficiency of development processes.
The e-motor's active parts have been designed to achieve a very high torque density and efficiency range in the medium speed range. The use of the machines together with an optimally selected gear stage offers high efficiency within the respective load cycles. The high power density offers the OEM more space for battery and central drive unit.
The e-motor´s active parts are designed for direct oil cooling. Compared to water jacket cooling with the same active part size, the continuous power of the system can thus be increased, which in turn enables a more compact construction of the machines. By using a shared oil circuit, the electric motor can be integrated directly into the transmission compartment.
For the transmission, guaranteeing a certain gearing load capacity, lubrication and meeting the clutches’ requirements in the sliding phase during shifting are essential requirements placed on the oil.
In contrast, oil-cooled e-motors have specific requirements for the oil, aimed at their electrical and material-related properties.
The integration of these different requirements needs thorough coordination of oil properties and specifications to ensure the functionality of both subsystems.
