With electricity prices on the increase, maximum efficiency is also becoming more important for Electric Multiple Units. Anticipating this development, ZF therefore developed ZF Get2. As opposed to conventional EMU transmissions, this innovative transmission concept has two gears thanks to an additional starting gear. The multispeed transmission continuously moves the load point in such a way that the electric motor and converter always work in a favorable efficiency range. This saves energy and provides greater tractive power at the same level of drive power. These advantages can be brought to bear particularly during the starting processes and thus for metro applications, since the distances between metro stops are short. In this application, ZF Get2 generates energy savings of up to five percent compared to one of the most advanced current metro drive systems.
During constant travel, ZF Get2 also reduces energy consumption because it has a neutral position in addition to the two gears. If this is activated, the rail vehicle is in coasting mode, meaning that all drives not required to maintain the speed are decoupled in order to avoid losses. During deceleration, the multispeed concept makes it possible to use the respectively optimal recuperation point of the traction machine, which improves energy recuperation.
ZF’s multiple traction system also maintains the same high level of passenger comfort in spite of the gear changes: The intelligent electronic control system engages all drive units in the vehicle automatically in serial sequence and thus prevents noticeable interruptions of tractive force. The gears are changed extremely fast. The train accelerates smoothly.