What gearbox does a Prius have?
The Prius uses an electronic continuously variable transmission (eCVT) that is part of Toyota’s Hybrid Synergy Drive. Rather than a traditional set of gears, it relies on a planetary gear-set-based transaxle to blend power from the gasoline engine and electric motor for smooth, efficient driving.
How the Prius' eCVT actually works
The system centers on a power-split device: a planetary gear set that links the internal combustion engine, the propulsion electric motor, the generator, and the wheels. By varying the relative speeds and torques of these components, the vehicle can accelerate smoothly without shifting gears. The engine can run at its most efficient RPM range, electric motors can drive the wheels at low speeds, and regenerative braking can recover energy.
Key aspects of the design include:
- The engine is connected to the sun gear of a planetary gear set; the electric motor/generator is connected to the planet carrier; the ring gear is linked to the drive wheels.
- The arrangement splits and combines torque between the engine and the electric motor to produce a continuously variable drive ratio.
- There are no conventional fixed gears; control software continuously adjusts the apparent gear ratio to optimize efficiency and performance.
- Regenerative braking uses the electric motor as a generator to convert kinetic energy back into stored electrical energy in the battery.
In practice, this means the Prius can run on electric power at low speeds, run the engine when needed for efficiency or charging, and provide seamless acceleration without the sensation of shifting gears.
Does it differ by Prius generation?
All modern Prius generations (from the second generation onward) use the Hybrid Synergy Drive eCVT architecture with the same fundamental power-split approach. Variations over time mostly involve refinements in control software and improvements to battery and motor hardware, not a change in the basic gearbox concept.
Summary
The Prius does not have a traditional automatic or manual gearbox. It employs an electronic CVT built around a planetary gear-based power-split transaxle as part of Toyota’s Hybrid Synergy Drive, allowing seamless blending of gas engine and electric motor power for efficient, smooth driving across conditions.
