Combination Locks

Combination Locks

Combination locks work on a series of flat, round disks that have notches and pegs (one of each, one
set per disk) along their
circumference. Notches are referred to as "gates". The
first tumbler determines the last digit of the combination, and is actually attached
to the
dial directly. As the dial is turned, the peg of the first tumbler catches on the middle tumbler’s
peg, dragging it along. As the dial
is turned further, the middle tumbler latches on to the
peg of the last tumbler, all three turning together. Turning all the tumblers is
known as
"clearing" the lock, and must be done before attempting to operate the lock. For the lock
to open, the gate on each disk must
align up with the pawl (breaking arm) of the bolt.

Dialing the first digit of the combination aligns the last tumbler’s gate to the pawl. Before
dialing the second digit, the dial must be
turned one complete turn in the opposite direction
(assuming a three tumbler lock, twice for a four digit one). Rotating in the original

direction to the last digit will align the first tumbler’s gate, and the lock can open. Modern safe
combination locks are impossible to
crack (literally). Many innovations have given high
quality locks this degree of security. Burglars learned to feel the gates and pegs
rotate
about the lock, allowing them to manipulate the tumblers into their proper position. To combat this,
a searted front tumbler was
designed to create shallow "false gates". The false
gates are difficult to distinguish from the actual gates. To combat this problem, safe

crackers would hook up a high speed drill to the dial. This would wear the tumblers edges smooth,
eliminating the bothersome
shallow gates. Still, despite their security, cheap combination
locks are far from foolproof.

Determining an Unknown Combination

The most
common and difficult to open of these small disk tumbler locks are the Master combination padlocks,
and they are quite
popular. With practice, they CAN be opened. The newer the lock is, though,
the more difficult it will be to open at first. If the lock has
had a lot of use, such as that
on a locker-room door where the shackle gets pulled down and encounters the tumblers while the

combination is being dialed, the serrated front tumblers will become smoothed down, allowing easier
sensing of the tumblers. So, until
you have become good at opening these locks, practice
extensively on an old one. Here’s how.

Step One

First, clear the tumblers
by engaging all of them. This is done by turning the dial clockwise (sometimes these locks open more
easily
starting in the opposite direction) three to four times. Now bring your ear close to
the lock and gently press the bottom back edge to the
bony area just forward of your ear canal
opening so that vibrations can be heard and felt. Slowly turn the dial in the opposite direction. /> As you turn, you will hear a very light click as each tumbler is picked up by the previous
tumbler. This is the sound of the pickup pegs
on each disk as they engage each other. Clear
the tumblers again in a clockwise manner and proceed to step two.

Step Two
/> After you have cleared the tumblers, apply an upward pressure on the shackle of the padlock.
Keeping your ear on the lock, try to hear
the tumblers as they rub across the pawl; keep the
dial rotating in a clockwise direction.

You will hear two types of clicks, each with a
subtle difference in pitch. The shallow, higher pitched clicks are the sound of the false

gates on the first disk tumbler. Do not let them fool you-the real gates sound hollow and empty,
almost nonexistent.

When you feel a greater than normal relief in the shackle once
every full turn, this is the gate of the first tumbler (last number dialed).
This tumbler is
connected directly to the dial as mentioned earlier. Ignore that sound for now. When you have
aligned the other two
tumblers, the last tumbler’s sound will be drowned out by the sound of
the shackle popping open.

Step Three

While continuing in a clockwise
direction with the dial, listen carefully for the slight hollow sound of either one of the first
two
tumblers. Note on the dial face where these sounds are by either memorizing them or
writing them down. Make certain that you do
not take note of the driving tumbler (last number
dialed). If you hear and feel only one hollow click (sounds like "dumpf"), chances are /> that the first number could be the same as the last one.

You should have two numbers
now. Let us say one of them is 12 and the other is 26. Clear the tumblers again just to be safe and
stop at
the number 12. Go counterclockwise one complete turn from 12. Continue until there is
another "dumpf" sound. After the complete
turn pass 12, if you feel and hear a
louder than normal sound of a tumbler rubbing on the pawl, the first tumbler is properly aligned /> and the second tumbler is taking the brunt of the force from the shackle-you are on the right
track. When the second tumbler has
aligned in this case, you will feel a definite resistance
with the last turn of the dial going clockwise. The final turn will automatically
open the
shackle of the lock. If none of these symptoms are evident, try starting with the number of the
combination, 26, in the same
way.

Step Four

If the lock still does
not open, don’t give up. Try searching for a different first number. Give it a good thirty or forty
minute try. If you
play with it long enough, it will eventually open. The more practice you
have under your belt, the quicker you will be able to open
these padlocks in the future.

Using a stethoscope to increase audibility of the clicks is not out of the question when
working on disk tumbler locks, though usually
not needed for padlocks. A miniature
wide-audio-range electronic stethoscope with a magnetic base for coupling a piezoelectric-type

microphone is ideal for getting to know the tumblers better.

• UNLOCKING MASTER COMBINATION PADLOCKS
• manipulating locks.
• Tubular Cylinder Locks Picking
• OPENING COMBO LOCKS
• OPENING COMBO LOCKS