Antonov and Jaguar collaborate on multi-speed EV transmission
Antonov's 3-speed transmission, developed with input from Jaguar's Limo-Green project, promises up to 15% efficiency gains for electric vehicles.
Antonov, the British engineering specialist, has developed a 3-speed automatic transmission for electric vehicles, with the project originating from work with Jaguar on the Limo-Green hybrid demonstrator. The system, which targets improved efficiency and performance, was presented at the IDTechEX Electric Vehicles conference in Stuttgart in July 2011.
While most electric vehicles use a single-speed or, less commonly, a two-speed gearbox, Antonov's design aims to address the varying efficiency of electric motors across their speed range. Electric motors deliver maximum torque from zero rpm, but their efficiency can drop to 60-70% at lower speeds, compared to a peak of around 90%. By introducing a multi-speed transmission, Antonov claims it is possible to keep the motor operating closer to its optimal efficiency band, thereby increasing range or reducing battery size.
Jaguar Limo-Green project origins
The collaboration with Jaguar began in 2009 as part of the Limo-Green project, a range-extended hybrid limousine concept. Initially, Antonov was asked to supply a fixed-ratio gearbox, but the brief expanded to explore additional gears for better off-the-line acceleration and higher cruising speeds. The resulting 3-speed automatic transmission delivered a 14.7% improvement in efficiency during testing, without sacrificing performance. This allowed for either increased range or the use of a smaller, lighter battery pack.
The transmission is compact enough to fit into existing tunnels and features a conventional twin-shaft layout, dual lubrication pumps (one mechanical, one electric), and a dual-clutch system for smooth gear changes. Antonov also highlighted the possibility of adapting the design for four speeds if required.
Efficiency and cost benefits for electric vehicles
Beyond the headline efficiency gain, Antonov argues that a multi-speed transmission allows for the use of a lower-torque, lighter electric motor, reducing both cost and overall powertrain weight. Other advantages include improved launch acceleration, higher top speed, better hill-climbing ability for commercial vehicles, and quieter cruising. The system also enables more effective regenerative braking by optimising gear selection for energy recovery.
Antonov's approach also opens the door for telematics integration, allowing the vehicle to select the most efficient gear based on route data or battery state. For example, the system could prioritise range in a "limp-home" scenario or select lower gears for maximum regenerative braking when descending hills.
Industry recognition and next steps
The 3-speed EV transmission won the IDTechEx Electric Vehicles Land Sea Air Technology Award in 2011 for its technical contribution. Antonov subsequently partnered with Smith Electric Vehicles to test the system in prototype electric delivery vans, targeting commercial applications where efficiency and payload are critical.
Despite the clear efficiency gains, multi-speed transmissions remain rare in production electric vehicles, as many manufacturers continue to favour the simplicity of single-speed systems. Antonov's work with Jaguar and other partners demonstrates that transmission innovation could yet play a role in the next generation of electric drivetrains.
