UBC Supermileage Drivetrain
The UBC Supermileage team has competed in the Urban Concept Gasoline category of the Shell Eco-Marathon Americas competition since 2008. Previously, the drivetrain has been comprised of a centrifugal clutch mounted to the engine with a chain and sprocket system transferring power to the drive wheel while reducing the speed. While this method has proven to be robust and easy to maintain, it has had its disadvantages.
Design Goal
To redesign the drivetrain of UBC Supermileage’s urban concept vehicle to improve its fuel efficiency and performance at the 2015 Shell EcoMarathon Americas competition.
Project Description
The team successfully designed and built one of the first, if not the first, two-speed transmissions to be implemented at the Eco-Marathon competition. The final design was a 2-stage, 2-speed, overdriving transmission using a custom centrifugal clutch, a planetary gearbox, an electromagnetic clutch, spur gears, and sprag clutches. The planetary gearbox served as the first stage of speed reduction, and the combination of the electromagnetic clutch, spur gears and sprag clutches allowed for a high torque first gear that could be overdriven by a lower torque, higher speed second gear by engaging the clutch.