Resistant mechanical combination lock and improvements thereto

A combination lock with a combination dial operatively linked to a drive cam and a plurality of tumbler wheel assemblies rotatably stacked on a hub to form a tumbler stack within a lock case, each of said tumbler wheel assemblies having a tumbler gate, said drive cam having a drive cam gate for engaging a nose of a pivotable fence lever arm, said fence lever arm for retracting a slideable lock bolt when a correct combination is dialed, and an interlock mechanism in each said plurality of tumbler wheel assemblies, said combination lock comprising:

• (a) a combination tumbler ring having an inside radius for engaging said hub and a circumference digitated with micro-fingers, said circumference with radius R′ at the root of said micro-fingers and radius R at a crown of said micro-fingers;
• and
• (b) at least one interlock lever arm with a fulcrum for opposingly contacting said circumference of said combination tumbler ring, said interlock lever arm with first end having a plurality of micro-fingers disposed on an arcuate member with concave radius R, said micro-fingers of said interlock lever arm for interdigitatingly engaging said circumferential micro-fingers of said combination tumbler ring in a gripping action, wherein said circumferential micro-fingers and said interlock lever arm micro-fingers are formed with opposable crowns and roots and opposable flat-on-flat flank faces for cooperatively resisting rotational torque applied thereto when interdigitatedly engaged.

A combination lock with a combination dial operatively linked to a drive cam and a plurality of tumbler wheel assemblies rotatably stacked on a hub within a lock case, each said tumbler wheel assemblies having a tumbler gate, said drive cam having a drive cam gate for engaging a nose of a pivotable fence lever arm, said fence lever arm for retracting a slideable lock bolt when a correct combination is dialed, and an interlock mechanism in each said plurality of tumbler wheel assemblies which comprises a feature selected from:

• (a) an interlock mechanism in each said plurality of tumbler wheel assemblies comprising:
• (i) a combination tumbler ring having an inside radius for engaging said hub and a circumference digitated with micro-fingers, said circumference with radius R′ at the root of said micro-fingers and radius R at a crown of said micro-fingers;
• and
• (ii) at least one interlock lever arm with a fulcrum for opposingly contacting said circumference of said combination tumbler ring, said interlock lever arm with first end having a plurality of micro-fingers disposed on an arcuate member with concave radius R, said micro-fingers of said interlock lever arm for interdigitatingly engaging said circumferential micro-fingers of said combination tumbler ring in a gripping action, wherein said circumferential micro-fingers and said interlock lever arm micro-fingers are formed with opposable crowns and roots and opposable flat-on-flat flank faces for cooperatively resisting rotational torque applied thereto when interdigitatedly engaged;
• (b) a duress feature comprising:
• (i) a duress tumbler wheel assembly for use at any position in said tumbler stack;
• (ii) a microswitch assembly with microswitch module, said microswitch assembly comprising interchangeable spacer blocks configured so that the microswitch module can be changeably positioned in operative relation to said duress tumbler assembly at any level of said tumbler stack;
• and
• (c) a fence control feature comprising:
• (i) an excentric trigger pin mounted on an outside face of said drive cam;
• and
• (ii) a trigger plate pivotably mounted at a fulcrum on said lock case, said trigger plate having an overcenter arm, a stop arm, and a cam follower arm disposed around a common pivot point on said lock case, wherein said overcenter arm is operatively coupled to said fence lever arm by a coil spring such that said nose is normally biased to a first position raised above said drive cam and drops down toward said drive cam gate in a second position for less than 6 degrees of rotational arc when resiliently urged by said excentric trigger pin acting on said cam follower arm, and said trigger plate comprising at least one feature selected from the group consisting of:
• (A) a bracket for mounting said overcenter spring, wherein said bracket is vertically elevated above said overcenter arm and displaced counterclockwise from the rotational line of the overcenter arm by a distance of about 4 millimeters, said clockwise displacement reducing the stretch of the spring and sharpening the transitional arc from first position to second position;
• (B) a half-moon-shaped apron formed on said overcenter arm, said half-moon-shaped skirt extending under said coil spring and over said nose and said drive cam gate;
• and
• (C) a plastic body, generally formed of nylon with glass fill, having translucency, resilience, and increased resistance to wear.