Unpickable Lock Idea

unpickable.txt

For several types of locks, the best known means of bypassing them is by by picking.

For many locks, including pin-tumbler, wafer-tumber, disc-tumbler, and tubular lock, picking requires not just a pick to fiddle with the innards of the lock, but also a tensioner to keep the fiddled-with components in the position that the person picking the lock has moved them to.

This idea is to make a lock which cannot be tensioned, which in turn means that it cannot be picked.

Here's how it works:

The lock plug, the part of the lock which the user puts the key into, and which would normally be rotated by turning the key, and which is normally connected to the latch or deadbolt, is instead welded/bolted/splined to the housing / lock body, and is not connected to the latch or deadbolt.  Naturally, it is unable to be turned.

The lock cylinder, which the plug would normally rotate within, and which is normally welded/screwed/etc to the housing, is, in this lock, connected to the latch or deadbolt, and is capable of being turned to unlock the lock.  Naturally, it should only turn if the correct key is inside the plug.

There are a few additional components:

First, there is a lever which the user can press to attempt to unlock the door.  Pressing it down compresses two springs, a strong one and a weak one.  When the lever is fully down, the strong spring disengages from the lever, while the weak spring remains attached.  The weak spring's purpose is to reset the lever, and the strong spring's purpose is to ATTEMPT to rotate the cylinder and unlock the lock.

Second, there is an epicycle gear.  This gear's purpose is to allow the strong spring to either unlock the lock, or reset itself without unlocking the lock.  The expanding strong spring connects to the planet carrier of the epicycle gear, the ring gear connects to the cylinder, and the sun gear spins a dashpot.

If the correct key is in the lock plug, the expanding strong spring turns the planet carrier, which turns the cylinder, which unlocks the lock; in this case, the sun gear and dashpot rotate a tiny amount.

If the wrong key is in the lock plug, or no key, the expanding strong spring turns the planet carrier, and since the cylinder is unable to turn, the ring gear doesn't turn, and the sun gear and dashpot slowly rotate for a couple seconds.

In either case, just before the strong spring is fully uncompressed, it disengages from the planet carrier, and when actually fully uncomrpressed, re-engages with the lever.

For a person wanting to pick open the lock, there is a very very brief window of oppourtunity to do so, while the strong spring is rotating the dashpot.  Once the spring disengages from the planet carrier, tension on the cylinder releases, and the lock's pins drop back into the plug, causing all progress to be lost.

Thus, unless the cylinder has very few pins, and is made horribly imprecisely, it ought to be unpickable.

Naturally, this doesn't mean the lock won't have other weaknesses, merely that it will have one fewer weakness than most common locks.