50 History Of Locks
Kromer’s Krosimplex Safe Dial
Another insightful article in our History & History series from Brian Morland, Curator
of The History of Locks Museum. This time, Brian tells us about another treasure
from the Museum’s extraordinary collection - Kromer’s Krosimplex Safe Dial.
A LOT TO THINK ABOUT…
Dialling a traditional 3 or 4 wheel
combination lock requires a certain
amount of mental dexterity. There is a lot
to think about, the combination numbers,
the start direction, accuracy of dialling,
number of rotations for each number,
changing direction, and all this ideally
held in memory. Add to this any day-today preoccupations that the user might
have then you have a recipe for a high
number of frustratingly failed dialling
attempts.
The normal procedure for dialling a four
wheel combination lock might be:• Turn the dial five times in a clockwise
direction carefully stopping at the first
combination number.
• Turn the dial four times in an anticlockwise direction carefully stopping
at the second combination number.
• Turn the dial three times in a
clockwise direction carefully stopping
at the third combination number.
• Turn the dial two times in an anticlockwise direction carefully stopping
at the fourth combination number.
• Turn the dial clockwise to open.
^ One of Bill Stanton’s practice lock,
from around the late 1940’s, with which
he learned the necessary techniques
including trouble shooting.
^ Bill Stanton pictured here in the mid
1960s when he was working on Kromer
projects including what was to become
known as the Krosimplex dial.
You can see that the sequence requires
concentration particularly to aligning
numbers when changing direction, as any
over or under dialling requires the whole
sequence to be started again.
The locksmith has an advantage over
the banker, commercial user or private
user in that he knows intimately what is
going on in the lock and the reason for
counting rotations and changing direction
and, therefore, these details are intuitive
to him whereas to the customer user they
are just an annoyance.
One common problem, sometimes
encountered by users when dialling a
combination, was mentally counting
the number of rotations for a particular
number before changing direction for
A contemporary artists sketch of the
dial from Kromers own booklet.