TOYOTA / HYBRID KNOWLEDGE BASE

01 / INTERACTIVE STUDY

Three shafts.
One transmission.

The Toyota Prius Power Split Device links engine and motor speeds through one planetary gearset. Change the inputs and observe the relationship.

e-CVT / PRIUS II

Local study copy
Alex Hart · eahart.com ↗

All resources are stored here.
No internet is needed after launch.

MODEL IN MOTION

Explore the speed relationship

The diagram requires Canvas support. The description and equation are available below.

Loading local model…

Speed controls
0 rpm

0 — off; working range 1000–4500 rpm.

0 rpm

Negative speed means reverse.

Calculated MG1 speed0 rpm
Vehicle speed ≈0 km/h

You can also drag the original handles on the diagram. The sliders support keyboard input: Tab to focus, arrow keys to change.

HOW IT WORKS

You set two values.
Geometry sets the third.

The sun gear, ring gear and carrier mesh together. They can rotate at different speeds and even in different directions, but their speeds always follow one relationship.

In Alex Hart's modelMG1 = 3.6 × ICE − 2.6 × MG2All values are revolutions per minute.

Leave the engine off and increase MG2 speed: the sun gear turns backwards. Then increase engine speed. MG1 can change direction while vehicle speed stays the same.

ANOTHER VIEWThe original 3D-style illustration is a separate frame animation and is not linked to the sliders.

How the complete powertrain works and what changed: Prius 10–60, alpha and other Toyota hybrids →

What this model shows

This is an educational kinematics demonstration based on second-generation Prius parameters. It shows the relationship between rotational speeds, but does not calculate torque, load, losses, battery charge or real-vehicle control algorithms. Its limits and warnings apply to this demonstration, not to every Prius generation.