| Classic Old
Style Slot Machines
Behind the scenes or under the hood
of the classic old style slot machine
runs 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 brings the spinning reels
to a stop, and sensors communicate the
position of the reels to the payout
system. A coin detector initially registers
that a coin has been inserted and unlocks
a brake so the handle can move.
Over the years, manufacturers have tried
dozens of approaches to arranging these
elements. The diagram above shows one
such design.
The design above includes three reels
mounted on a central shaft. The central
shaft also supports three notched discs,
which are connected to the three reels.
A second shaft below the central shaft
supports a kicker, a piece of metal
comprising three paddles. The kicker
paddles are lined up so they can push
against the notches on the three discs.
The second shaft also supports a series
of connected stoppers, teeth that lock
into the notches on the discs.
The kicker and the stoppers are both
connected to springs, which hold them
in a standby position. The kicker is
held in place behind the discs, while
the stoppers are held up against the
discs, locking them into place.
So here is what happens when a player
pulls the handle:
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The handle rotates a hook mechanism,
which grabs hold of the kicker,
pulling it forward (toward the player).
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A catch on the opposite end of
the kicker grabs a control cam piece
and pivots it forward. This rotates
a series of gears connected to the
control cam. A spring pulls the
control cam back to its original
position, but the gear assembly
slows it down considerably -- the
gears act as a mechanical delay.
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When the control cam is pivoted
forward, it releases a spring-mounted
cam plate extending across the back
of the machine. |
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The control cam also pulls the
stoppers away from the notched discs.
As the kicker keeps moving, it pushes
the stoppers against several catches
on the cam plate. These hold the
stoppers in place, so the discs
and reels can rotate freely. |
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As the handle continues to move
the kicker, the kicker paddles push
the discs forward briefly. When
the handle is pulled all the way
back and the kicker has passed the
discs, the bottom of the hook mechanism
moves up against a slanted surface.
The slant pivots the hook forward,
which causes it to release the kicker.
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The kicker spring jerks the kicker
backward at a good speed. The kicker
paddles hit the notches on the discs,
spinning the reels rapidly. |
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While all of this is happening,
the control cam is slowly returning
to its original position. When it
does return, it pushes the cam plate
back, which releases the stoppers.
The different catches holding onto
the different stoppers are positioned
so that the cam plate will release
the stoppers one at a time. Each
stopper springs forward and locks
into a notch, holding the reel in
position. |
From the player's point of view, here's
how it looks. The player pulls the handle.
There is a clunk, and the three reels
start spinning. Then the three reels
stop abruptly one at a time, followed
by the payout (if necessary). The "stopping
one at a time" part builds suspense.
If the first reel stops on the jackpot
symbol, then you have to wait for the
next reel to stop to see if it is a
jackpot, and then finally the third.
If all three display the right symbol,
the player wins.
Conventional mechanical slot machines
eventually gave rise to electrical machines
that worked on similar principles. In
an electrical machine, the reels are
spun by motors and the stoppers are
generally activated by electromagnets,
but the game basically plays out the
same way. Electrical machines have more
sophisticated money-handling systems,
like those you might find in a vending
machine, and flashier light and sound
displays.
In both types of systems, once the
reels have come to a stop, the slot
machine needs to read whether the player
has won or lost. In the next section,
we'll examine some systems for making
this determination.
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