Scooter: variator, rollers, movable cheeks, springs?!?!

As you're probably aware, there's no clutch lever, selector or gearbox on a scooter. And yet, the gears shift automatically, allowing the machine to move forward. How does it work?

To make it easier to explain, remember how your bike works: chainrings at the front, sprockets at the rear and 2 derailleurs (1 for the front and 1 for the rear) to regulate the position of the chain. When you're on the small chainring and the large rear sprocket, you've got power but you won't go very fast, whereas if you've got a large chainring and a small rear sprocket, you'll have trouble getting going but you'll be able to reach your maximum speed. Derailleurs act as gearboxes, moving the chain.

Scooters are a bit like that :-)

> The front derailleur and chainrings: this is the variator.

> Rear derailleur: the push spring

> Sprockets: this is the pulley where the clutch is mounted (it's the only part you won't find on a bike ^^).

The chain: this is the belt.

Now that we've mastered a little technical vocabulary, let's get down to the nitty-gritty.

When you start the scooter, the motor drives the speed controller. The variator is made up of 2 cheeks, one fixed and one mobile. It's in the movable cheek that we find the famous rollers. The belt is clamped between the 2 cheeks and runs at the same speed as the engine.

When you accelerate, the rollers inside the movable cheek spread outwards, causing the movable cheek to move. For the curious, this is centrifugal force at work. For those who don't know what centrifugal force is, take a bucket, put some water in it and give it a whirl. If you don't get wet, you've got it.

The cheeks will come together as the rollers accelerate and move, forcing the belt upwards. Bingo, you're changing chainrings. Ain't life grand?

But what's going on at the back of the scoot? We've lost the sprockets... As the belt is not extensible, if it goes up at the front, it goes down at the rear. So we change sprockets and go faster and faster.

What about the scooter clutch ? It allows the rear wheel to turn as soon as the whole assembly turns fast enough, and not before, so that the scooter doesn't idle.

How does a scooter clutch work? It's very basic, so let's start by breaking down the clutch assembly:

- 1 bell

- 2 or 3 linings, most of the time

- Springs holding the linings.

When you accelerate, the variator/receiver pulley assembly drives the clutch. When the clutch rotates fast enough, the springs allow the linings to separate, bringing them into contact with the bell and driving the wheel.

At ixtem-moto .com, you'll find all the parts you need for your scooter.