Manipulation resistant combination lock with magnets

An improved manipulation resistant combination lock for impeding unauthorized opening of a combination lock through manipulation of the lock components, wherein said lock comprises:

• a housing;
• a bolt slidably mounted to the housing;
• a fence lever moveable about a pivot;
• a fence member on said fence lever;
• a drive shaft rotatably mounted on said housing;
• a drive cam keyed to said drive shaft, said drive cam having an outer periphery;
• a plurality of tumbler wheels that are rotated within said housing by said drive shaft with each of said tumbler wheels having respective gates that align with said fence member when said drive shaft is rotated in a predetermined manner;
• drive cam magnet means mounted on said drive cam outer periphery;
• and
• a fence lever magnet mounted at one end of said fence lever for reacting with said drive cam magnet means for repelling said fence lever away from said drive cam during a portion of the rotation of said drive shaft.

A method of preventing unauthorized opening of a combination lock of the type having a pivotal fence lever having a nose portion facing the outer periphery of a rotary drive cam having an inwardly extending drive cam gate having first and second side edges extending inwardly from its outer periphery, said method comprising the steps of:

• applying force to said pivotal fence lever to urge it away from the periphery of the rotary drive cam in response to rotation of the first side edge into facing relationship with said nose portion;
• and, similarly,
• applying force to said pivotal fence lever to urge it away from the periphery of the rotary drive cam in response to the rotation of the second side edge into facing relationship with said nose portion;
• said steps of applying force to said pivotal fence lever being effected by the application of magnetic force;
• and
• said application of magnetic force being effected by bringing the axes of two magnets into substantial alignment with each other with like poles of each magnet facing each other so that said magnets are repelled from each other.