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Hagerty Employee

Go to school on the Chevrolet Bolt's clever Drive Unit

When you look at the Chevrolet Bolt's Drive Unit, it's immediately clear that simplicity plays a vital role in a drivetrain's efficiency. The "Drive Unit" is Chevy-speak for the compact motor and gear set that replaces a traditional engine and transmission in the Bolt EV. A V-8 engine alone uses 100+ moving components, but the Bolt's entire powertrain uses fewer than five gears to transmit power from the rotor, the electric motor's only spinning part, to the wheels.


In this video, Weber State University Professor John D. Kelly breaks down the Bolt's drivetrain into its core components, allowing us to understand the system from the inside out.


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The good Prof Kelly is obviously being paid by the hour.  What he calls a 'CV shaft' is more accurately known as a half-shaft;  each of these wheel drive axles has a CV (constant velocity) joint at each end.

While the Bolt driveline may be simple, it's obviously no more compact than a four-cylinder combustion engine, automatic transaxle, and fuel tank when you add the volume of the control modules, coolers, and sprawling battery pack to the compact AC motor and final drive unit.