The new transmission, designed for Class 7-8 commercial vehicles, is currently in the testing phase with major OEMs and is set to debut in 2022, the company says.
The transmission is the latest addition to Eaton’s growing eMobility portfolio of electrified vehicle (EV) transmissions and other componentry, which also includes medium-duty two- and four-speed models that are also currently in production with several OEMs, the company says.
“Electric buses and trucks need to be able to go up hills and run at highway speeds when they are fully loaded,” says Scott Adams, senior vice president, eMobility, Eaton. “Our solution is to expand the range of the motor by adding an EV transmission. With this addition, the vehicle can perform well on hills and efficiently at highway speeds with a smaller, less costly motor.”
The heavy-duty four-speed EV transmission solves the primary issue related to single-speed drives: contradictory requirements for high efficiency at top speeds and increased torque at launch and low speeds, Eaton says. Fine-pitch helical gears ensure a smooth, low-noise operation, while the Eaton Transmission Control Unit’s shifting strategy is designed for fast gear changes and maximum efficiency, which extend range and battery life.
The transmission is based on traditional and efficient lay shaft architecture typical of AMTs but is designed specifically for electric commercial vehicle applications. Unlike traditional commercial vehicle transmissions, Eaton’s four-speed EV gearbox does not have a clutch and shifts are synchronized using the traction motor, Eaton says. It also operates at higher speeds than its traditional internal combustion gearbox counterparts, and gears are optimized for typical electric motor performance and power curves for maximum efficiency.
By providing higher output speed capability and torque range than a direct-drive system, the transmission enables the usage of a smaller, lighter electric motor for large commercial vehicles, which cuts down on the cost, a major buying point for commercial EV operators, the company says.
