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Inside the table · Roulette

How does a roulette wheel work?

The bowl stays still. The rotor turns. The ball takes its own route. Look inside a European roulette wheel and see how those movements become one result.

8 labelled parts37 pockets8 knowledge checks
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SO IRISH ACADEMY · INSIDE THE TABLE

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3D lesson · English narration
The Roulette Wheel: cutaway model ready to explore
20 steps · 8 questions · explore at your own pace
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  1. The bowl

    The bowl is the stationary outer part of the wheel. It supports the ball track around the rim and the rotating Rotor in the centre, but never moves itself. The whole assembly rests on this stable base while the croupier sets the rotor spinning and launches the ball.

  2. The ball track

    A narrow groove runs around the upper rim of the bowl: the ball track. The croupier launches the ball along it in the opposite direction to the rotor. The ball circles the track several times, gradually loses momentum and drops inwards towards the Deflectors and then the Rotor.

  3. The deflectors

    Several fixed metal obstacles sit on the slope between the track and the Rotor. These are the Deflectors, sometimes called diamonds. Their number varies between wheel designs. A collision deflects the ball unpredictably before it falls further inwards. Even a single impact can change its direction at the last moment.

  4. The rotor

    The rotating inner part of the wheel is called the Rotor. The croupier sets it spinning before each launch, while the ball travels in the opposite direction. These opposing movements are part of the game: the rotor and the ball initially circle in opposite directions until the ball loses momentum and drops from the track.

  5. 37 pockets

    Metal dividers around the rotor separate 37 pockets: the numbers 1 to 36 and the Single zero. There are 18 red pockets, 18 black pockets and one green pocket for zero. Red and black alternate around the ring, with the green zero pocket interrupting that sequence.

  6. The number ring

    The Number ring does not put the numbers in ascending order. Clockwise from zero, the sequence is 32, 15, 19, 4, 21, 2, 25, 17, 34, 6, 27, 13, 36, 11, 30, 8, 23, 10, 5, 24, 16, 33, 1, 20, 14, 31, 9, 22, 18, 29, 7, 28, 12, 35, 3, 26. This spreads high, low, odd and even numbers around the ring.

  7. The turret

    The cross-shaped turret in the centre acts as the croupier’s handle. With one hand, the croupier uses it to set the Rotor spinning. With the other, they launch the ball along the track in the opposite direction. Together, these actions create the familiar opposing motion of ball and rotor.

  8. The ball in motion

    The rotor and the ball travel in opposite directions until the ball loses momentum. It drops past the Deflectors towards the pockets, bounces several times and eventually comes to rest. The winning number is only settled once the ball has stopped in a pocket.

  9. All the parts at a glance

    From the outside in: the bowl, ball track, Deflectors, Rotor, 37 pockets, Number ring, turret and ball. The rotor assembly turns inside the fixed bowl while the ball follows its own path. This exploded view separates the components so you can see how they fit together.

Questions about the roulette wheel

What is the difference between the bowl and the rotor?

The bowl is the fixed outer base. The Rotor is the rotating inner part. Picture a disc inside a stationary bowl: the disc moves while the bowl stays still. Both components are highlighted in the model.

What are the small metal pieces on the slope for?

Those are the Deflectors. They are fixed to the slope and redirect the ball when it hits them. They do not rotate with the rotor. The ball passes through this area on its way from the outer track to the pockets.

Why are there 37 pockets instead of 36?

The numbers 1 to 36 occupy 36 pockets: 18 red and 18 black. The green Single zero adds one more. That is why this European wheel has 37 pockets. Zero has its own pocket and belongs to neither of the other two colours.

Why are the numbers not in ascending order?

The Number ring follows a fixed sequence that does not count upwards. High, low, odd and even values are spread around the ring. The numbers are not rearranged between rounds. Their order describes the layout of the wheel, not the order of future results.

What rotates, and in which direction?

The Rotor turns inside the fixed bowl. The ball starts along the outer track in the opposite direction. The Deflectors stay still. Use “Pause rotation” to stop the animation and compare the parts at your own pace.

Can you explain the ball’s route again?

First, the ball circles the outer ball track. As it loses momentum, it drops onto the slope, where the Deflectors may redirect it. It then bounces towards the numbered pockets. The outcome is only settled once the ball comes to rest in a pocket.

An illustrative European single-zero wheel. Rotate and separate the parts to see their relationship.

Useful terms
Deflectors
Small, fixed metal obstacles on the slope between the ball track and the rotor. They deflect the ball unpredictably before it drops into a pocket.
Rotor
The rotating inner part of the wheel, carrying the 37 numbered pockets. It spins in the opposite direction to the ball.
Number ring
The fixed sequence of 37 numbers on the rotor. They are arranged in a non-ascending order that spreads high, low, odd and even values around the ring.
Single zero
The single green pocket for zero. Together with the 36 other numbered pockets, it brings the total to 37.
The mechanics, explained

What happens inside the wheel?

A roulette wheel has a stationary outer bowl and a rotating inner rotor. The dealer sends the ball around the outer track in the opposite direction to the rotor. As the ball slows, it leaves the track, crosses the sloping surface and settles into a pocket. The number beside that pocket identifies the result.

Reference: Roulette wheel design and ball path, US20200211327A1.

The parts and their jobs

PartWhat it does
BowlThe fixed outer body that supports the wheel.
Ball trackThe outer circular track where the ball begins its journey.
DeflectorsFixed metal pieces on the slope that can redirect the descending ball.
RotorThe inner assembly that rotates within the bowl.
Pockets and number ringThe ball settles into a pocket; the adjacent number identifies it.
TurretThe raised structure at the centre of the wheel.

Follow one spin, from launch to result

Watch the rotor and ball separately in the lesson. First, the rotor turns while the ball circles the outer track in the other direction. As the ball loses momentum, it drops towards the rotor. It can strike a deflector and bounce before settling. A passing ball above a number is not yet the result: look at the pocket where it finally comes to rest.

Why are there 37 pockets?

This model represents a European single-zero wheel: 1 to 36, plus a green zero. There are 18 red pockets, 18 black pockets and one green pocket. The zero is an additional outcome; it is not part of red or black. The wheel’s number sequence is fixed, even though it does not run in numerical order.

The wheel and the betting layout do different jobs

The wheel produces the numbered result. The printed layout is where players place bets on that result. A number’s neighbour on the wheel need not be its neighbour on the layout. Use the exploded view to find the number ring, then try the roulette trainer to connect a wheel result with the bets on the table.

Real wheels can look different

Track angles, pocket depths, finishes and zero configurations vary between products. Cammegh’s Continental, for example, uses a shallower ball track and a smaller rotor with deeper pockets than its Mercury 360 family. Our model explains the components; it is not a scale replica of every casino wheel.

Reference: Cammegh Continental: construction and options.

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