Anatomy of a Pinball Machine

To understand why pinball is so addictive and so beloved, you have to actually get inside the machine.

Drop a quarter—or four—in the coin door, and a pinball machine will whir to life. Boom: lights flash, the scoreboard resets, and a stainless-steel ball clinks into place, ready to hurtle down the shooter alley toward a maze of ramps, bumpers, and traps.

Casual players tend to experience pinball as a frenzied series of events that inevitably culminate in a ball breezing past a set of flippers, down a drain, and back to its home beneath the glowing playfield. Without an expert touch, the game can feel almost happenstance, the ball zigging and zagging at the mercy of small movements from flippers and sinking and rising surfaces. In reality, though, pinball is anything but random. You just have to open a machine to learn its secrets.



In early versions of pinball, players used wooden cue sticks to shoot the ball onto the playfield. Today, they use spring-loaded knobs called plungers. When tugged all the way back and released, the plunger will send the ball flying around the playfield with careless abandon, into a potential series of landmines. The plunger shot isn’t all luck, though: designers, who can choose from more than a dozen spring strengths to fine-tune the plunger’s tension, consider plunging the ball a “skill shot”—which means that if the player hits the ball with just-so force, they’ll launch it into a specific target that will net them big points.

Every pinball machine is a mini marvel of engineering. Its guts are a complex series of interconnected machines designed with Rube-Goldbergian precision. “We like to describe it as a world under glass,” says Eric Meunier, a game designer at New Jersey-based Jersey Jack Pinball, one of the last remaining pinball manufacturers in the United States.

Pinball has changed drastically over the years, from running exclusively on solenoids and relays—coils of wire that, when energized with electricity, make pinball mechanics move—to relying primarily on microprocessors and circuit boards. Even still, every old or new game starts more or less the same way. “The first three inches of a game are always the same,” Meunier says. “But after that, the ball could go anywhere.”

After the player pulls the spring-loaded plunger, the ball will travel through the shooter alley and enter a mini amusement park of obstacles that impact its path through the game. Modern pinball machines are built from thousands of parts, if you count things like screws and washers, and most come loaded with a few well-known components. These include flippers, the small mechanical wings players activate by pressing a button on the side of the game’s cabinet; pop bumpers, the mushroom-shaped targets that send the ball flying when touched; ramps, to direct the ball to a new area of the playfield; magnets hidden below the playfield to stop the ball or divert its path; a logic board to process the ball’s position on the playfield and keep track of game play and score; a drain, the hole at the bottom of the playfield where the ball goes when you lose; and a tilt bob, a mechanical sensor under the machine that can sense when a player is tilting the machine too far. It’s up to the designer to lay out the components in imaginative ways and create new toys and tricks that can entice collectors and arcade owners to buy a machine.



Designers use these inclined paths to direct the ball onto a raised area of the playfield. In modern games, ramps are built from plastic or metal and are precisely positioned to catch the ball after a power shot, or from the point at which the ball flies off the flipper at the highest velocity. In early games, the playfields weren’t designed with ramps that were directly shootable; they were more like decorative design additions meant to make the playfield more interesting. Because balls require a certain amount of velocity to enter a ramp, designers rarely position a ramp after a weaker orbit shot, which is the path a ball takes when it travels through a lane at the outer edge of a game.

For designers like Meunier, a pinball game is a puzzle; each component, whether a ramp or a wire, must be in place for the full picture to come into focus. Designers are often trained as electrical or mechanical engineers, and they approach pinball with a scientific eye. They can spend years mocking up playfields and confabing with the art department before a game ever gets built. “It’s a symbiosis,” Meunier says of the process. “The art has to tie into the rules, and the rules have to tie into the shots.”

Most designers start crafting a game with a narrative in mind, which is usually dictated by a film or TV show. From there, they build the playfield’s shots and components around that storyline. Early versions of a game are designed on something called a whiteboard: a piece of slanted wood acts as a physical blueprint, allowing designers to lay out a complex series of components that ensure a game plays as planned. “The way I design a game is to have a lot of broad features that a non-pinball-player—we call them ‘casuals’—can see and easily achieve when they walk up to the game,” Meunier explains.

The average game is designed to last three minutes, a length of time established back when bars and arcades had to turn a profit off the machines. (Today, most of Jersey Jack’s machines are privately owned.) Designers can tweak the layout of a playfield to be more or less challenging by doing things like widening an outlane (the lanes at the far side of the playfield that lead to the drain), or adding a bumper closer to the drain. And game owners can fine-tune software to determine the power behind an electrical jolt to the flipper, which can also impact game play.

Things such as ramps, lanes, spinners, and blinking lights are meant to provide visual targets, and are not particularly complicated in and of themselves: pull the spring-loaded plunger and the ball goes flying. Press a button and the flippers flick. Shoot the ball up a ramp and it’ll roll back down. But when arranged inside a pinball machine’s cabinet, the components create a deliberate maze of cause and effect, all set up to challenge the player and—ideally—make the arcade money.



Pop bumpers have been a mainstay of pinball machines since the game started using solenoids. In the 1930s and ’40s, they were called “dead bumpers,” since the totems merely provided a stationary obstacle in the playfield. Modern pop bumpers, which have changed little since the 1950s, have a plate at the bottom that functions like a 360-degree electromechanical sensor. When the ball rolls onto the skirt underneath the bumper, it activates a solenoid, which then triggers a mechanism at the top of the bumper to clamp down. This motion shoots the ball back into the playfield at random, often into other nearby pop bumpers. Because there’s little control over where the ball goes after it touches a pop bumper, designers usually place them toward the top of the game to avoid draining the ball too quickly.

Pinball wasn’t always so aggressively engineered, and early machines relied on chance. In the 18th century, French aristocrats played a game called bagatelle, an indoor version of croquet in which a player would use a cue to shoot a ball across a wooden table and attempt to sink it into various holes. In the late 1800s, bagatelle evolved into a proto-Plinko setup, in which players would use a spring-loaded plunger to send a metal ball up a sloped playfield, where it would score points as it clinked past a field of pins.

Pinball’s predecessors required little skill, which explains why the game was considered a form of illegal gambling in most U.S. states until 1947, when the pinball manufacturer Gottlieb introduced the arcade game Humpty Dumpty. Gottlieb’s game was the first to use flippers; this new tool gave players more control over where to shoot the ball, which eventually led to its legalization as state courts decided that pinball was a game of skill, not chance.

You can still find pinball machines lighting up casinos today. But modern pinball is anchored by rationale, says Mark Gibson, whose traveling exhibition, Fun With Pinball, explains the science behind pinball components such as flippers, bumpers, and solenoids. “Pinball machines are programmed with a set of rules that behave very predictably,” he says. “What makes it seem arbitrary is the motion of the ball.”



Pinball’s magic is just as much about what’s happening under the playfield. Designers build hidden ramps under the playfield to move the ball from one position to the next, with a touch of magic: balls enter subway paths through a hole in the playfield and roll, unseen, to the end of the subterranean ramp, where they're kicked back up to a new location on the playfield. Since this visual effect relies on gravity to get the ball to where it needs to go, most subway paths are built to mimic the 6.5 degree pitch of the playfield. Every so often, though, designers will build subway ramps deep enough to run in the opposite direction of the game’s slant, allowing the ball to reemerge at the top of the playfield for an extra surprise.

From the 1940s to ’70s, pinball machines functioned like mechanical computers, relying on a complex series of physical components such as relays and switches to activate every part of the machine. “It was basically just a bunch of switches that got actuated and went from step to step to step,” says Michael Schiess, director of the Pacific Pinball Museum in Alameda, California, whose Visible Pinball Machine puts the game’s insides on display.

Lift the colorful ramp on one of Schiess’s transparent games, and you’ll see an organized mess of solenoids, wires, and motors that work together to tell the machine when to activate a flipper or add 500 points to your score. Lift the ramp on one of Meunier’s games, and you get a vastly different view: at Jersey Jack, Meunier designs “solid-state games,” named for the interior logic board that handles all the computing involved in modern pinball machines.



First introduced in 1947, these 3-inch plastic wings are the driving force of pinball. Flippers are powered by solenoids, little wire coils that when energized with electricity make the flippers flick back and forth, and they react instantaneously when the buttons on the side of the machine’s cabinet are pressed. Flippers are the primary way to move a ball through the playfield; they introduce an element of control to what can otherwise feel like a totally randomized game. The truly skilled wield them like hands, catching and holding balls and pressing the buttons with precise pressure to ensure the ball travels exactly where it needs to go.

Instead of relying on individual mechanical parts to tell the scoreboard when to register a point or when a chime should sound, solid-state games have abstracted all of that away, with circuit boards that can track the ball’s location on the playfield, keep score, activate lights and sounds, and power general game play. “We’re essentially building big PCs,” he says.

Though the computer is the brains of a modern pinball machine, a player’s path through the playfield ultimately depends on skill. Every ball is equal when it kicks up to the shooter lane, but finesse (or, more likely, lack thereof) determines where the ball rolls. It’s that tension—between engineering precision and the unpredictable reality of physics—that keeps players plugging the coin door time and time again. “That’s the nature of pinball,” says Schiess. “And that’s why it’s survived for so long.”

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