A lock is composed of a series of spring-loaded stacks of pins. Each pin stack is composed of two pins that are stacked on top
of each other: the bottom pin, which touches the key when it is inserted,
and the driver or top pin, which is spring driven. When the correct key is
inserted into the lock, all of the key pins and driver pins align,
allowing the cylinder to be turned. When no key or the wrong key is in
the lock, the pin misalignment prevents the cylinder from being turned.
When lock bumping, the key is initially placed one notch out along the
keyway. Bumping the key inward forces it deeper into the keyway. The
specially designed teeth of the bump key impact all of the pins in the
lock. The key pins transmit this force to the driver pins.
Because the
pin movements are highly elastic, the driver pins separate from the key
pins for a split second and are then pushed back by the spring. Even
though this separation only lasts a split second, if a light force is
applied to the key, the cylinder can be turned and the lock can be
opened.
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