The vast majority of mechanical locks in use today are of
the "pin and tumbler" variety.
They have an outer cylinder, an inner cylinder, and pins
which are supposed to prevent these two cylinders from
rotating relative to one another unless the correct key is
The biggest weakness
of the pin and tumbler lock is
"picking", where these two cylinders are twisted relative to
one another using some sort of tensioning tool, and then a
lockpick is inserted into the keyhole to move around the
This idea is prevent picking by preventing tensioning.
Tensioning in a common lock is possible because the outer
cylinder is usually incorporated into the lock housing, while
the inner cylinder is rotated by the key. This means that a
would be thief has physical access to both cylinders.
In my idea, this is reversed: the inner cylinder is
incorporated into the lock housing, and is unable to rotate,
while the outer cylinder is what rotates and moves the
deadbolt, or allows/prevents the latch from moving.
The outer cylinder is completely hidden and protected
inside of the lock housing, and a would-be thief has no
direct access to it, and as you will see, no indirect access
With only access to one of the cylinders, tension cannot be
applied, and the lock cannot be picked.
Now, I'm sure you are wonder, how does the lock actually
First, the TL;DR version: Push the key into the lock, the
key pushes on a rod, when the rod is fully pushed in by the
key, the lock magically changes from locked to unlocked,
or vice versa.
Next, the expanded version:
The rod inside of the lock's keyway has two springs
attached to it; a lightweight spring to reset the rod and
push out the key, and a stiff spring to drive some gears.
When the rod is pressed all the way into the lock by the
key, the stiff spring detaches from the rod, connects to the
planet gear of an epicyclic gear, and expands, rotating the
When the stiff spring is when fully extended, it disconnects
from the planet gear, and reconnects to the rod.
The ring gear of the epicyclic gear is connected to the
outer cylinder of lock and also to the deadbolt or whatever
locks/unlocks the lock.
The sun gear of the epicyclic gear rotates a dampener or
dashpot of some sort.
If the correct key is in the lock then the energy from the
expanding mainspring quickly moves through the epicycle
gear into the ring gear, and successfully locks or unlocks
After a success, lock becomes ready the instant the key is
If an incorrect key is in the lock, then the energy from
expanding main spring moves through the epicycle gear
into the sun gear, and spins the dashpot, putting the spring
into to it's "ready try again" state within several seconds.
After a failure, not only does the key need to be removed
for the lock to be ready, but the main spring needs to be
fully expanded, however long that takes.
This idea does not prevent lock bumping, nor the use of
tryout keys, but should *significantly* increase the time
between one attempt and the next.
This concept should work with pin tumbler locks, wafer
tumbler locks, and disc detainer locks.
Downsides: Your friendly neighborhood locksmith might
need to destroy the lock if you lose your keys and need to
open the lock.