If you have a scooter, odds are that it doesn’t have a regular manual transmission that you operate with a shifter.
But the transmission isn’t automatic either – instead, it has something known as a “CVT transmission.”
And contrary to popular belief, it’s not the same as an automatic transmission.
In this blog post, you’ll learn:
- What a CVT transmission is and how it works
- Differences between a CVT and an automatic transmission
What is a CVT?
CVT stands for “Continous Variable Transmission,” a standard transmission for vehicles – particularly scooters.
A CVT contains two pulleys connected with a belt. One of these pulleys is connected to the crankshaft and the other one is connected to the final drive:
- The “drive pulley:” fixed in place
- “The driven pulley:” slides on a shaft
As the driven pulley slides on the shaft, the belt moves up or down and changes the size of the fixed pulley, depending on the direction.
If the belt moves down, the fixed pulley gets smaller.
If the belt moves up, the fixed pulley gets bigger – which allows the diameter of each pulley to increase or decrease while the engine’s running.
The changes in size between the pulleys change the gear ratio between them. Depending on which pulley increases, the engine’s torque or RPM increases:
- If the drive pulley’s diameter increases, the engine produces more RPMs
- If the driven pulley’s diameter increases, the torque increases
For more of a context, take a look at this video which shows a scooter CVT in action:
CVT vs. Automatic Transmission
A common misconception is that a CVT gearbox is the same as an automatic gearbox.
While both types don’t have gearshift levers or require the rider to shift through gears, they’re not the same.
Unlike an automatic transmission, a CVT transmission doesn’t have any separate gears. Instead, the two pulleys function as one “long” gear.