• Slot machines originally used mechanical inner workings to ensure as random of a spin as possible, making use of gears, levers, notched discs, and more.

  • Players originally pulled a handle to engage the machine and get the slot reels spinning.

  • Charles Fey invented the first slot machine in San Francisco, California, in 1887.

  • The slot machine became the first mechanical device that could take a wager, collect losing bets, and pay off winning bets without a human dealer.

  • Vintage mechanical slot machines have become sought-after collector’s items.

Any gambler who’s watched a vintage movie about Las Vegas has likely noticed the iconic mechanical slot machine. These traditional slot machines, unlike today's games which rely on a random number generator, operated using tangible moving parts to determine outcomes.

Charles Fey from San Francisco is credited with inventing the very first mechanical slot machine in the late 19th century, aptly named the "Liberty Bell." Since its introduction, slot machines have evolved with various technological advances. Yet, for many years, players' fortunes depended on the intricate mechanics of these beloved machines, where wins and losses were determined by gears and levers rather than digital computations.

Keep reading to find out a bit about how these mechanical slot machines worked and if they can be found for playing today.

How Do Mechanical Slot Machines Work?

Most slot players take the act of popping a few dollars in a slot machine or opening up their mobile phone or laptop to spin some reels for granted. It's pretty easy to get in on the action and modern games feature plenty of “bells and whistles” – from high-definition video with mind-blowing graphics to cinema-style sound effects to easily-changeable betting options.

But these types of options weren’t always the case. Early machines featured single denominations of stakes and very few bells and whistles (although bells were a common symbol on early machines). Despite these limited options, early slots were highly popular with gamblers. Machines are the main draw and gambling revenue drivers for most casinos around the world.

“There has never been any other gambling device which has produced such enormous profits with so little effort on the part of the operator,” Scarne’s New Complete Guide to Gambling notes. The author adds: “The slot machine is the only mechanical device with a mechanical banker that collects losing bets, pays off winning bets, and makes fewer mistakes than any human dealer in any casino banking game.”

Early machines were manufactured in machine shops and made use of mechanical gadgets instead of techno-wizardry, although there definitely was some skilled engineering to make these gambling devices work. Many of these classic games made use of typical machine-style components including:

  • a cabinet (often metal in the early days) to encase the mechanics

  • gears

  • levers

  • metal shaft to support the spinning reels

  • notched discs

  • kicker

  • connected stoppers

Classic machines may vary a bit, but this is the general idea of how the mechanical inner workings of a slot machine work. A metal shaft is a key part of the machine’s functions by supporting the reels (usually only three on older machines), which display various symbols and signify a certain action such as a win, loss, or jackpot.

The shaft is connected to a handle protruding from the machine (hence the nickname “one-armed bandit”). Some modern machines feature a handle as well, although they only activate the slot’s computer software. But in these older machines, the handle actually worked to get the mechanical reels spinning and in motion.

A braking system brings the spinning reels to a stop to signal a win or loss. Later machines also made use of sensors to enable payouts based on the position of the reels. More advanced mechanical reels eventually also used coin detectors to initiate the game after a coin was inserted into a “slot” – giving the games the name “slot machines.” This mechanism released a brake so a player could move the handle and go for a spin.

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What is the Kicker and Stoppers?

There’s a bit more to this mechanical process with devices called “kickers” and “stoppers” playing a major role. The three reels on the central shaft also house three notched discs. A second shaft supports the slot kicker.

This piece is made up of three paddles that intersect with and push against the disc notches. This second shaft also supports several connected stoppers, which protrude into the disc notches. The kicker and stoppers are joined to springs, which lock them in a “standby” position.

When the handle is pulled, these are released until they come to a stop and the reels display that spin’s results. Line them up just right and some slot token or cash are headed your way. The actual specific mechanics of the machine varied by manufacturer, but as noted, this is the general idea of how mechanical slots work overall.

It seems as the world became more industrialized and new manufacturing processes gained favor, creating a machine that mixed entertainment and gambling just seemed inevitable. Who knew how immensely popular these games would actually become?

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“With the emphasis on streamlined production and mechanization that came with the Second Industrial Revolution in the late 19th Century, it was only a matter of time before someone invented a machine that could help people gamble faster and more efficiently,” author David Schwartz notes in Roll the Bones: The History of Gambling.

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Which Pays Better, Video or Mechanical Slot Machines?

Part of the fun of playing a slot is the hope that a nice win is heading your way. But cash payouts weren’t always the case. Charles Fey invented the first coin-paying slots in San Francisco in 1895. Earlier machines were more mere amusement devices and paid out prizes such as:

  • cigars

  • chewing gum

  • candy

  • more free spins on the machine

  • free drinks

But Fey’s machine revolutionized the gaming industry, transforming this amusement device into a gambling slot machine. His first machine, known as the Liberty Bell, paid out 50 cents when three bells lined up across the three reels.

Slots can now be found in casinos throughout the globe as well as online on real-money gaming platforms and in social media mobile gaming options. Gaming options have changed dramatically but the general idea that payouts come via finding fortuitous luck on those spinning reels remains.

Obviously, as advances were made, payouts advanced beyond that initial 50-cent win on a Liberty Bell. Players could wager higher denominations and also win on multiple lines.

Modern video slots offer much easier ways to win at much higher denominations. However, players must also be willing to wager more per spin because of so many paylines now available to players.

Modern slots also offer the chance to win progressive jackpots as well, which can reach staggering sums. These are reached by games being linked across numerous locations and jurisdictions. A small portion of each spin is put into the progressive payout pool and players getting extremely lucky can take all or even a smaller share of that total.

In general, players now have many more opportunities to win on a video slot machine or a game with spinning reels but also using modern software and technological engineering.

How Do Mechanical Slots Produce Random Results?

The mechanics of a mechanical slot help produce random spins based on the actual spinning of the reels. The kicker and stoppers eventually help bring them to a stop as the reels begin to slow. Is this truly random?

That depends on one’s perspective. But in the age of computer software, probably not a perfectly random outcome. The mechanics of these games may have favored certain results occasionally but manufacturers were working with real machine parts and worked to make these results as random as possible. Gaming commissions also worked to make sure these were fair games.

This is much different than modern slots. These games make use of a random number generator (RNG) to predetermine an outcome before a player even spins the reels. The software predetermines the outcome based on slot machine algorithms for a completely random result. Modern slots are much more computer and software than an actual machine.

How to Fix Vintage Mechanical Slot Machines?

Many people love the feel of old mechanical slot machines, but sometimes they can have problems.

Here's a simple guide to fixing the most common issues:

  • Safety First!

Before diving into repairs, always remember to unplug the machine or ensure it's not connected to any power source. You're dealing with metal parts, and safety should always be a priority.

  • Jammed Coin Mechanism:

A frequent problem with mechanical slot machines is the jamming of the coin mechanism.


- Open the front panel using a slot machine key or a suitable replacement.

- Carefully remove the coin mechanism from the machine.

- Inspect for foreign objects, bent coins, or debris. If found, gently remove them.

- Check moving parts for any visible wear or damage. If worn out, consider replacing them or seeking professional help.

  • Stuck or Non-Spinning Reels:

If your reels aren’t spinning, the cause might be a broken or misaligned spring, or an issue with the internal gears.


  1. Carefully remove the machine's back panel.

  2. Examine the springs connected to the reels. Replace any that appear stretched or damaged.

  3. Check the internal gears. Clear any debris or accumulated dirt using a soft brush.

  4. If gears appear worn out or damaged, sourcing replacements might be necessary. It's advisable to consult with a specialist if you're unfamiliar with the gear system.

  • Non-Functional Pull Lever:

If the lever isn't working, it could be due to a disconnect between the lever and the internal mechanism, or it might be broken.


  1. Open the side or back panel to access the lever mechanism.

  2. Check for disconnections or breaks in the linkage. Reattach or replace as necessary.

  3. Apply a light lubricant to the lever joints to ensure smooth movement.

  • Misaligned Payout System:

Sometimes, the machine doesn't release coins even after a win.


  1. Open the machine's front or back panel.

  2. Examine the coin release pathway for any obstructions and remove them.

  3. Check the payout discs and tubes for misalignments. Ensure they line up correctly with the payout slot.

  • Regular Maintenance:

To keep your machine running smoothly:

  1. Regularly clean and dust the internal components.

  2. Apply a light machine oil to moving parts annually to reduce friction and wear.

  3. Always handle internal components gently to avoid causing inadvertent damage.

What Happened to Mechanical Slot Machines?

As computers became more in use in the 1980 to 2000s, slots began to transform. Slowly those mechanical inner workings were replaced by more modern technology. Developers could create more entertaining and innovative games using new technology.

Even the use of coins and slot tokens faded away. Players could use cash and then be paid out in vouchers which could easily be used in other machines. All these changes revolutionized the industry and this saw a surge in the game’s popularity. Players loved numerous new features such as:

  • user interactivity

  • video clips

  • multiple paylines

  • bonus rounds

  • free spins

  • Pop culture tie-ins such as movies, TV shows, and musical acts

Many slot machines began featuring a narrative element or at least a common theme, such as ancient mythology, animals, or almost anything else imaginable that might resonate with players.

This new breed of slot machines began replacing those older machines featuring real mechanical reels and inner workings. Many were scrapped but some vintage games remain sought after by collectors. Perhaps you’ve seen one in a friend’s game room or a museum such as the Mob Museum in Las Vegas.

A few Las Vegas casinos still offer the chance to gamble on some vintage machines. Some may feature a bit of computer technology but offer the best chance to gamble on classic mechanical slots. For those looking to play some slots of a bygone era, the best place to find some is probably in downtown Vegas. Grab a bucket of quarters, drop a few in the “slot,” pull the handle, and hopefully a nice win is heading your way.

Where to Find Vintage Mechanical Slot Machines for Purchase

Before purchasing an old mechanical slot machine, ensure it's legal to own one in your jurisdiction. Some places restrict ownership based on the machine's age or prohibit it altogether.

Where to Buy:

  1. Online Auctions: Websites like eBay often list vintage slot machines. Always verify the machine's authenticity and the seller's reputation.

  2. Specialty Retailers: Some shops specialize in antique slot machines, such as San Diego Antique Slot Machines or Nation's Attic.

  3. Forums & Clubs: Join slot machine enthusiast forums or clubs. Members might share leads or sell their own machines.

  4. Local Antique Stores: Depending on your location, nearby antique shops might occasionally stock vintage slot machines.

  5. Classifieds: Check local classifieds or platforms like Craigslist or Facebook Marketplace. Ensure you verify the item's authenticity and the seller's trustworthiness.

Buying Tips:

  • Condition Check: Determine if the machine is operational or needs repairs. Consider potential restoration costs.

  • Return Policy: For online purchases, ensure there's a clear return policy in case of discrepancies.

  • Remember, when transporting your purchase, handle with care to protect its delicate mechanisms.

Frequently Asked Questions

How do mechanical slot machines work?

These older machines make use of gears, levers, discs, and other mechanical inner workings to determine the results of a spin of the reels. Early machines featured only machine inner workings whereas today machines make use of software and technology to determine wins and losses.

Can players win more on a mechanical slot or a modern video slot?

Modern machines offer numerous ways to pay, high denominations to wager (and win), and the opportunity to win progressive jackpots.

Did mechanical slots feature random results?

The outcomes of a slot were as random as possible based on the technology at the time. The reels spun after pulling the handle and eventually stopped due to the mechanics found inside the slot cabinet.

Sean Chaffin
Sean Chaffin

Sean Chaffin is a longtime freelance writer, editor, and former high school journalism teacher. He has covered the poker and gaming industry for many years.