A lock assembly, comprising:
- an outer housing having a front end, a rear end, a first bored cylindrical cavity from the rear end to a point near to the front end, and a second smaller bored hole axially coincident with the first bored cavity and extending from the frontal end of the first bored cavity through the front of the outer housing;
- an intermediate cylinder having an overall length of the first bored cavity of the outer housing, an overall diameter to slidably and rotatably fit the first bored cavity of the outer housing, a longitudinally and centrally bored cylindrical cavity from its front end to a point near to its rear end having a diameter greater than the diameter of the second bored hole of the outer housing, and a circumferential groove machined completely around its outer cylindrical surface being positioned to avoid intersection with any other subsequent machining of this intermediate cylinder;
- an inner cylinder having a diameter to slidably and rotatably fit the bored cavity of the intermediate cylinder, a length matching the length of the bored cavity of the intermediate cylinder, a front cylindrical extension axially coincident to the inner cylinder itself and of a diameter to slidably and rotatably fit the second bored hole of the outer housing, a centered and longitudinal key hole cavity extending from its front end towards its rear end but not extending all the way through its rear end which key hole cavity has an oddly configured cross-section of overall rectangular shape with a narrow width and a height less than the diameter of its front cylindrical extension and its top being along one narrow side;
- a lever arm attached to the rear end of the intermediate cylinder;
- a plurality of regular cylindrical locking pin bores extending radially from the center of the key-hole of the inner cylinder through the top of the key hole and continuing through the intermediate cylinder and through the outer housing and each having a diameter larger than the width of the key-hole of the inner cylinder, and the diameter of the portion of each of these bores that passes through the intermediate cylinder is additionally made slightly different from the diameter of the portion of each of these bores that passes through the outer housing;
- a maximum number of cylindrical pins of minimum practical lengths that slidably fit each of the regular locking pin bores and that do not extend outside the inner cylinder;
- a minimum number of cylindrical locking pins of random lengths that slidably fit each of the plurality of locking pin bores and that do not extend outside the intermediate cylinder, but one of these pins for each locking pin bore straddles the boundary between the outer surface of the inner cylinder and the surface of the bore in the intermediate cylinder, this being the means of locking the inner cylinder from rotating within the intermediate cylinder;
- a single cylindrical locking pin for each of the plurality of locking pin bores of necessary length to allow space above it within its locking pin bore which pin slidably fits its locking pin bore and straddles the boundary between the outer surface of the intermediate cylinder and the surface of the first bore in the lock housing, this being the primary means of locking the intermediate cylinder from rotating within the lock housing;
- a compression spring for each of the plurality of locking pin bores of a diameter to slidably fit each of the locking pin bores holding the stacks of locking pins in their locking positions;
- a short cam groove circumferentially machined into the surface of the inner cylinder having end walls that are radial and perpendicular to the long axis of the inner cylinder, the bottom surface of this groove forming a cam surface that has its center nearest to the long axis of the inner cylinder and its two ends at a farther distance equal for both from the long axis of the inner cylinder, and this whole short cam groove having no intersection with the key hole cavity of the inner cylinder;
- an additional locking pin bore being on the radial line from the central longitudinal axis of the inner cylinder that passes through the center of the short cam groove of the inner cylinder extending from the surface of the bore in the intermediate cylinder to the outer surface of the lock housing;
- a bottom cylindrical pin to slidably fit the additional locking pin bore being of a length that extends from the cam surface of either end of the short cam groove to the boundary between the outer surface of the intermediate cylinder and the surface of the first bore in the lock housing whenever the inner cylinder is rotated to position either end of the short cam in alignment with the additional locking pin bore;
- a top cylindrical locking pin slidably fitting on top of the bottom pin within the additional locking pin bore having a length short enough to leave space above it in the additional locking pin bore and being the secondary means that locks the intermediate cylinder to the lock housing when the inner cylinder is rotated to a position bringing the center of the short cam in alignment with the additional locking pin bore;
- a compression spring for the additional locking pin bore of a diameter to slidably fit the additional locking pin bore holding the stack of two pins in their locking position;
- a bore hole through the lock housing coinciding with the inner curved surface of the first boring of the lock housing but not coinciding with any other boring of the lock housing, coinciding with the groove of the intermediate cylinder, a tightly fitting pin or screw inserted within this bore hole and having a part of this pin or screw occupying part of the space of the groove of the intermediate cylinder, this being the means to retain the intermediate cylinder within the lock housing yet allowing the intermediate cylinder to rotate within the lock housing;
- a dimple of a shape less than demi-spherical machined into the outer curved surface of the intermediate cylinder in a position not coinciding with any other boring or grooving of the intermediate cylinder;
- a last radial bore hole through the lock housing centered on a radial line directed perpendicularly from the central longitudinal axial line of the first bore hole of the lock housing which line passes through the center of the dimple of the intermediate cylinder, extending from the surface of the first bore hole of the lock housing through the outer surface of the lock housing;
- a spherical ball slidably fitting inwardly into the last radial bore hole of the lock housing;
- a compression spring slidably and outwardly filling the last radial bore hole of the lock housing to hold the spherical ball within the dimple of the intermediate cylinder;
- a removable plate or cap or a plurality of removable plates or caps of common design to plug the outer ends of the plurality of regular locking pin bores and the outer end of the additional locking pin bore and outer end of the last radial bore hole holding the ball and spring;
- a flat-bladed key having a body of a cross-section that matches and is slidably fitting into the key hole cavity of the inner cylinder and having a body length to match the length of the key hole cavity of the inner cylinder, provided with a plurality of ramped notches on its top edge of the same number and spacing to match and meet with the bottom ends of the plurality of the bottom most cylindrical locking pins within the regular locking pin bores, said ramped notches being machined to depths that cause all of the stacks of the cylindrical locking pins to be raised to such a level that the junction between a pair of the pins that normally resides within the confines of the inner cylinder for each of the plurality of regular locking pin bores coincides with the boundary between the outer surface of the inner cylinder and the surface of the bore in the intermediate cylinder, and also that the junction between a pair of the pins that normally resides within the confines of the intermediate cylinder for each of the plurality of regular locking pin bores coincides with the boundary between the outer surface of the intermediate cylinder and the surface of the first bore in the lock housing;
- whereby, when said key is inserted into the assembly and rotational torque is applied to it, rotation of the inner cylinder is possible and, at the same time, all of the regular cylindrical pin stacks are put in an unlocking position for the intermediate cylinder relative to the outer housing, whereupon rotation of the inner cylinder will cause rotation of the cam groove along with it thereby unlocking the secondary locking of the intermediate cylinder to the lock housing by the additional locking pin stack and further rotation gives connectivity of the end wall of the cam groove to the bottom pin of the additional locking pin stack and will thereby rotate the intermediate cylinder which has connectivity to the rearward lever or shaft that operates the bolt, dog, or stops of the locking device associated with this invention;
- and whereby, if any other key fitting to the assembly and not having correctly machined ramped notches is inserted into the assembly and turning torque is applied to it, rotation of the inner cylinder is still possible because of the maximum number of cylindrical pins operational at that level, but rotation may occur only to the point where the end of the cam shaft becomes connective to the bottom pin of the additional locking pin stack because the regular pin stacks will not all be found to be in an unlocked state at that limit of rotation.