Lock system with improved auxiliary pin tumbler stack

A lock system comprising:

• a key comprising a bow portion and a blade which longitudinally extends from said bow portion along a key centerline to a tip, said blade having a pair of spaced parallel top and bottom edges which are interconnected by opposed side faces, said blade being provided with surface irregularities which define the key bitting, a shaped rigid camming projection transversely extending from each of said edges, said projections being at least in part in alignment, a second of said projections extending outwardly a greater distance from said centerline when compared to the oppositely disposed first projection;
• a shell having a longitudinal axis, said shell including a first cylindrical portion having a first diameter, at least a first row of primary pin tumbler receiving chambers being located in said first portion, said shell having a second cylindrical portion which is also coaxial with said first portion, said second portion having a second diameter which is greater than said first diameter, an auxiliary pin tumbler receiving chamber being provided in said second portion, said shell further having a circumferential groove intermediate the ends of said second portion, said auxiliary pin tumbler receiving chamber intercepting said groove;
• a plug rotatably mounted in said shell, said plug having a face and further having a longitudinally extending keyway formed therein, said keyway having a first portion in registration with said shell first portion and a second portion in registration with said shell second portion, said keyway second portion opening through said face and extending into registration with said shell second portion, said plug also having first and second cylindrical portions of different diameter which are generally complementary to and received in said shell first and second portions, said plug defining at least a first row of primary pin tumbler receiving chambers in said first portion thereof, said first row of primary pin tumbler receiving chambers being alignable with said shell primary pin tumbler receiving chambers, said plug defining an auxiliary pin tumbler receiving chamber in said second portion thereof, said auxiliary pin tumbler receiving chamber being alignable with said shell auxiliary pin tumbler receiving chamber, first and second shear lines respectively being defined between said shell and said plug first and second portions;
• and
• pin tumblers reciprocally mounted in said receiving chambers, said pin tumblers each including at least a bottom pin and a driver pin, said pin tumblers including biasing means for urging a pin of each of said pin tumblers to a position of bridging a shear line when a key is not present in said keyway, wherein the auxiliary bottom pin has a recessed underside, and insertion of a properly bitted key into the keyway displaces said pin tumblers against associated biasing means whereby the interface between the bottom and driver pins is located on a shear line, the displacement of the pin tumbler positioned in said auxiliary pin tumbler receiving chambers to establish the shear line being caused by camming of the first projection against the underside of the auxiliary bottom pin until entry of the first projection within said recess to a detent condition, rotation of said plug relative to said shell being permitted by said pin tumbler displacement, the other of said key blade edge projections travelling in said shell groove during such relative rotation, whereby withdrawal of said key subsequent to said relative rotation is prevented by interference between said second projection and a side wall of said shell groove and by the recess of the auxiliary bottom pin retaining the first projection.

In a lock comprising:

• a shell having a longitudinal axis, said shell including a first cylindrical portion having a first diameter, at least a first row of primary pin tumbler receiving chambers being located in said first portion, said shell having a second cylindrical portion which is also coaxial with said first portion, said second portion having a second diameter which is greater than said first diameter, an auxiliary pin tumbler receiving chamber being provided in said second portion;
• a plug rotatably mounted in said shell, said plug having a face and further having a longitudinally extending keyway formed therein, said keyway having a first portion in registration with said shell first portion and a second portion in registration with said shell second portion, said keyway second portion opening through said face and extending into registration with said shell second portion, said plug also having first and second cylindrical portions of different diameter which are generally complementary to and received in said shell first and second portions, said plug defining at least a first row of primary pin tumbler receiving chambers in said first portion thereof, said first row of primary pin tumbler receiving chambers being alignable with said shell primary pin tumbler receiving chambers, said plug defining an auxiliary pin tumbler receiving chamber in the said second portion thereof, said auxiliary pin tumbler receiving chamber being alignable with said shell auxiliary pin tumbler receiving chamber, first and second shear lines respectively being defined between said shell and said plug first and second portions;
• and
• pin tumblers reciprocally mounted in said receiving chambers, said pin tumblers each including at least a rigid bottom pin and a confronting, rigid driver pin, said pin tumblers including biasing means for urging a driver pin of each of said pin tumblers to a position of bridging a shear line when a key is not present in said keyway, insertion of a properly bitted key into the keyway displacing said pin tumbler against associated biasing means whereby the confronting interface between the bottom and driver pins is located on a shear line;
• the improvement wherein the auxiliary bottom pin has an underside facing said keyway and said underside is recessed.

A key blank for a cylinder lock comprising:

• a bow;
• a blade longitudinally extending from said bow to a tip, and having a pair of longitudinally extending oppositely disposed and spaced edges, and side faces which connect said edges, one of said edges to be cut with bitting;
• and
• a projection extending outwardly to a nose, on each of said oppositely disposed edges, said projections being at least in part in alignment, one of said projections, extending from the edge to be cut, having a nose closer to the bow than the nose of the other projection, a length parallel to the edge that is greater than a width transverse to the edge and a compound convex cam profile, wherein said one projection as viewed from above the edge, presents a convexly contoured surface facing the tip of the blade.

A key blank for encoding to operate a coded lock of the type comprising:

• a shell having a longitudinal axis, said shell including a first cylindrical portion having a first diameter, at least a first row of primary pin tumbler receiving chambers being located in said first portion, said shell having a second cylindrical portion which is also coaxial with said first portion, said second portion having a second diameter which is greater than said first diameter, an auxiliary pin tumbler receiving chamber being provided in said second portion;
• a plug rotatably mounted in said shell, said plug having a face and further having a longitudinally extending keyway formed therein, said keyway having a first portion in registration with said shell first portion and a second portion in registration with said shell second portion, said keyway second portion opening through said face and extending into registration with said shell second portion, said plug also having first and second cylindrical portions of different diameter which are generally complementary to and received in said shell first and second portions, said plug defining at least a first row of primary pin tumbler receiving chambers in said first portion thereof, said first row of primary pin tumbler receiving chambers being alignable with said shell primary pin tumbler receiving chambers, said plug defining an auxiliary pin tumbler receiving chamber in the said second portion thereof, said auxiliary pin tumbler receiving chamber being alignable with said shell auxiliary pin tumbler receiving chamber, first and second shear lines respectively being defined between said shell and said plug first and second portions;
• and
• pin tumblers reciprocally mounted in said receiving chambers, said pin tumblers each including at least a bottom pin and a driver pin, said pin tumblers including biasing means for urging a pin of each of said pin tumblers to a position of bridging a shear line when a key is not present in said keyway, wherein the auxiliary bottom pin has an underside facing said keyway and said underside is recessed;
• whereby insertion of a properly bitted key into the keyway displaces said pin tumblers against associated biasing means such that the interfaces between all the bottom and driver pins are located on a shear line;
• wherein said key blank comprises
• a bow;
• a blade longitudinally extending from said bow to a tip and having a pair of longitudinally extending oppositely disposed and spaced edges, one of said edges to be cut with bitting for matching the coding of the primary tumbler stack, and side faces which connect said edges;
• and
• a camming projection interrupting the edge to be cut, and located adjacent the bow thereby forming a front edge portion to be cut and a back edge portion adjacent the bow, said projection rising from respective bases below the front and back edge portions to a nose, with the back edge portion higher than the front edge portion, a length parallel to the edge that is greater than a width transverse to the edge, and having a compound convex cam profile for facilitating entry of the projection into the recess of the auxiliary pin of said lock as the key is fully inserted in the keyway of said lock.