How Slot Machines Work

Author: Sylvia Garcia

Did you know that slot machines were originally installed in casinos as diversions for casual gamers? Unlike the ever-popular and traditional table games, slot machines don’t require any gambling knowledge and anyone can get in on a game with very little cash. This idea proved to be a monstrous success as slot machines have moved off the sidelines to become the most popular and most profitable draw in town, bringing in more than 60 percent of the annual gaming profits in the United States.

So how do they work? The technology of slot machines has evolved a lot over the years. The classic mechanical designs have been almost completely replaced by computer-controlled machines. Yet the game has remained the same. The player pulls a handle (or presses a button) to rotate a series of reels (typically three) that have pictures printed on them. Winning or losing is determined by which of these pictures line up with the pay line, a line located in the center of the viewing window. If each reel shows the same winning picture along the pay line (certain single images are sometimes winners as well), you win. The amount you win depends on which pictures land along the pay line.

The classic slot machine design works on an elaborate configuration of gears and levers. The central element is a metal shaft, which supports the reels. This shaft is connected to a handle mechanism that gets things moving. A braking system then brings the spinning reels to a stop, and sensors communicate the position of the reels to the payout system. A coin detector usually registers that a coin has been inserted and unlocks a brake so the handle can move.

These conventional mechanical slot machines eventually gave rise to electrical machines that work on similar principles. In electrical machines, the reels are spun by motors and the stoppers are generally activated by solenoids, but the game basically plays out the same way. Electrical machines also have more sophisticated money-handling systems, similar to those you might find on a vending machine, and flashier light and sound displays.

Payouts There are many different payout systems used in slot machines. In one of the simplest designs, a jackpot is detected by measuring the depth of notches in the discs that drive the reels. For example, when you put coins in one of these machines, they fall into a transparent case. The bottom of the case is a movable shutter that is connected to a metal linkage. Normally the linkage holds the shutter closed. But when the machine hits the jackpot, the third stopper shifts the linkage up, opening the shutter so the coins fall out of the machine.

Most modern slot machines have been designed to look and feel like the old mechanical models, yet work on a completely different principle. The outcome of each pull is actually controlled by a central computer inside the machine, as opposed to the motion of the reels. The computer uses step motors to turn each reel and stop it at the predetermined point.