Performance and Efficiency Comparison of 8-Speed Powershift Transmissions to Planetary Transmissions in Dump Trucks

摘要

Articulated Dump Trucks excel through their high productivity. The task is to transport a load as fast and secure as possible over a demanding terrain. For modern machines high fuel efficiency is of great importance also. Therefore the drivetrain components should be optimally harmonized to each other to achieve an efficient overall system. The main development targets for the Ergopower LII transmission for these vehicles were low transmission losses, a high overall ratio spread and small and even individual gear steps. The 8 gear powershift transmission with countershaft design achieves an overall ratio of 10.88 which allows low engine speeds also at high velocities. The constant gear steps of 1.4 enable gearshifts without disengaging of the torque converter lockup clutch over the whole velocity range, which leads to a high system efficiency. Through dynamic performance- and fuel consumption simulations the advantages of the Ergopower LII drivetrain compared to typical 6 gear inline transmissions with drop box could be confirmed. The results show extensive fuel savings mainly caused by more efficient operating points and lower torque converter losses.