Wrightspeed announced development of a two-speed Geared Traction Drive (GTD), an integrated inverter, electric motor, and two-speed transmission that shifts electronically, using software-controlled motor synchronization instead of clutches.
The GTD provides a maximum output torque per wheel of 1,893 lbs.-ft. in first gear, and 810 lbs.-ft. in second gear (180 mph max), the company announced.
With the successful integration of a multi-speed gearbox and an electric motor, Wrightspeed's GTD makes this performance available by eliminating the traditional compromise made in electric drivetrains between low-end torque and top-end speed, the company said.
Smaller and lighter than any other traction system of equal performance, the Wrightspeed GTD fits many architectures, including midrange trucks. Wrightspeed uses the GTD in its Digital Drivesystems that use electric drive with micro-turbine power generation including the Route, Wrightspeed's medium duty truck retrofit drivetrain.
Wrightspeed’s Digital Drivesystems move the complexity from mechanical systems into electronic and software systems, making them lighter, cheaper, and more efficient. Clutchless gear shifting is a good example of this, according to the company.
Traditional multi-speed transmissions use clutches (dry clutches, multi-disc wet clutches, or twin-clutch arrangements) and mechanical synchronizers to match speeds before gear engagement; this makes them heavy, expensive, and less efficient, Wrightspeed said. But with electric motors, it becomes possible to control the motor speed so precisely, and change it so quickly, that the gears can be engaged without clashing. The sync function that used to be performed by mechanical means has been shifted into software control of electronics, driving the electric motor with precision.
Wrightspeed's control software weighs nothing, costs nothing to manufacture, doesn't wear out, and uses the electronics that are already present to drive the motor, according the company.