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Security Technology: Spin Dial Locks

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In this post I’m going to give some background on spin dial locks and how past generations of spin dials had weaknesses.  I’ll then describe the features of the Kaba Mas X-09 electro-mechanical spin dial, which is generally acknowledged to be one of the “most secure” locks in existence.

S&G 8550 Spin Dial Lock

The Sargent & Greenleaf 8550 mechanical spin dial lock.

Spin dial locks range in price and complexity from the cheap Master dial padlocks found protecting high school lockers throughout the United States all the way to the modern X-09.  The principle behind a spin dial is simple; a “combination”, or sequence of numbers, corresponds to a notch cut into the side of the wheels.  When the notches are aligned and the bolt retracting mechanism is engaged, a “fence” slides into the row of notches and provides the leverage needed to retract the bolt (or in the case of a padlock, entering the correct combination releases the shackle).   Most spin dials use a standard sequence of three numbers, which, on a lock with a dial ranging from 0-100 allows for a million possible combinations. Read the rest of this entry »


Written by OSB

18/07/2011 at 06:06