Mécanisme intérieur d'une serrure à gorges à double panneton :


 
 

Lever-tumblers locks coverall those locks which keys set in action of the slabs, which tracing the code carved in the map of the same key, allow the sliding of the latch with the consequent opening of the lock.

The keys of lever-tumblers locks are defined keys double-bitted in the case of keys to two sides.

Such keys are composed from a ring or grip, from the fusto and from the wings or maps, where they come you practice of the milling (or carvings) that they constitute the coding or code of the key.

 In the slabs or gorges they are practiced of the throats of various heights, apt to make to slide to their inside, a fixed hinge perpendicular to the latch, called "mentonnet".

During the spin of the every key lastrina set in action from a motivating force, inserendosi in the correspondent milling (or tooth) practiced in the map of the key, raises of’an even height all’height of the respective tooth that, aligning the l mentonnet to the rabbet practiced in the lastrina, concurs to it and therefore to the latch of you slid to devious. You see fig. 2


 

 Being the number of slabs and the various realizable heights, to determine the number of codings or combinations of a lock to slabs, importance of’owing is evidenced l to increase the value of such parameters, therefore a lock with a greater number of slabs, will be surer than one lock with minor a number (always of course to parity than quality d’execution). The same speech varrà for the assegnabili heights to the teeth of the key.

The quality of a lock to slabs, depends in important way from the fabrication tolerances, than beyond to determinarne the good operation ne eventual attempts characterize the degree of emergency in’the comparisons d d’undesired openings.

And’opportune moreover that accorgimenti are previewed antimanipulation and antibottoming drill, and it arranges actions to elude attempts carried out with force keys.
 

The force key

The force key is a particular tool, assimilabile to a key with map lacking in carvings, than taking advantage of the own robustness, also in coding absence, it succeeds to gain the resistance offered from the slabs all’to be left over of the mentounet, determining therefore l’undesired sliding of the latch, united to the destruction of the same lock. You see Fig 3


 

 The sent jump of

A large disadvantage that characterizes the locks to double map is the sent jump of. Such defect happens in those cases where the spin of the key is not sufficient to sospingere the latch of the section necessary in order to to make to pass mentounet dall’the initial position, and therefore nell’appropriate center of one given sent, to the position of the successive sent one.

The lacked insertion mantounet nell’the appropriate center can determine, in presence of particular sollicitations (as an example one resistance to run regulating of the latch), the return of the latch in the position occupied before the spin of the key.
The spin of the even key to sending, but without the correspondent dragging of the latch, reaches to make to correspond to the carvings of the key (situated in the map of sends uneven sees 1° and 3° sent), the position of the slabs with coding of sends even (2° and 4° sent), determining the blocking of the lock. You see fig. 4

The main lawsuits that can determine the sent jump of are:
* Locks or keys excessive usurate,
* Locks with high values of tolerance,
* Copies of badly duplicate keys,
* Excessive hindering frictions the normal sliding of the latch.