US 4,412,437 AGranted

Rekeyable lock method and apparatus

AssigneeInnovative Research Corporation

InventorJerry R. Smith

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Abstract

A rekeyable cylinder lock includes removeable spacers between top and bottom tumbler pins, and a key bit device for removing a spacer from the pin chamber through the key way. The key bit device includes bitting thereon to position the spacer in the top pin chamber and a cut in the opposite side thereof adapted to capture the spacer from the top pin chamber and remove it from the lock. The spacer is preferably smaller in diameter than the tumbler pins, and the cut is large enough to receive the spacer but too small to receive the tumbler pin. In another embodiment of the invention, a key bit device is provided for placing a spacer into a pin chamber of the lock to rekey the lock. It includes a mechanism, such as a spring, in a cut on the back side of the key bit that is adapted to force a spacer out of the cut and into the pin chamber in the lock.

Claims3

Dependent claims

In rekeyable lock apparatus, including a lock cylinder housing with a cylindrical bore extending longitudinally therethrough an elongated top pin chamber in said housing perpendicular to and extending radially outward from said cylindrical bore, a cylindrical core positioned rotatably in said bore, said core having a longitudinal keyway therein for receiving a key bit and a bottom pin chamber extending radially inward from the peripheral surface thereof into said keyway, said bottom pin chamber being adapted to axially align with said top pin chamber, a top tumbler pin slideably positioned in said top pin chamber and a bottom tumbler pin slideably positioned in said bottom pin chamber, said core being rotatable when the interface between said top and bottom pins is aligned with the shear plane between the core and the cylinder housing and not being rotatable where a pin is positioned through said shear plane, the improvement comprising:

a disc-shaped spacer member positioned in said bottom pin chamber between said top pin and said bottom pin for providing an additional interface between said top and bottom pins adapted for alignment with the shear plane between said core and said cylinder housing, one interface being on the top of said spacer means and a second interface being on the bottom of said spacer means, said spacer member having a diameter less than said top tumbler pin, and
removal means for removing said spacer means from said pin chamber and ejecting it out of said lock apparatus, said removal means including an elongated key bit adapted for insertion into said keyway and having a bitting thereon adapted to position said spacer member in said top pin chamber with said second interface between said spacer member and said bottom pin aligned with the shear plane between said core and said cylinder housing such that said core can be rotated within said cylinder housing, said key bit also having a cut therein opposite said bitting and of a depth corresponding to the thickness of said spacer member and a length less than said top tumbler pin and greater than said spacer member, said cut being adapted to receive said spacer member therein when aligned with said top pin chamber and to carry said spacer member out of said core when said key bit is withdrawn from the core with the spacer member in said cut.

In lock apparatus having a lock cylinder housing with a cylindrical bore extending longitudinally therethrough and an elongated top pin chamber in said housing perpendicular to and extending radially outward from said cylindrical bore, a cylindrical core positioned rotatably in said bore, said core having a longitudinal keyway therein for receiving a key bit and a bottom pin chamber extending radially inward from the peripheral surface thereof into said keyway, said bottom pin chamber being adapted to axially align with said top pin chamber when said core is positioned in said cylindrical bore in such a manner that said top and bottom pin chambers form a common pin chamber, a top tumbler pin slideably positioned in said top pin chamber, and a spacer member positioned between said top and bottom pins, said core being rotatable when an interface between a pin and the spacer is aligned with the shear plane between the core and the cylinder housing and not being rotatable when a pin is positioned through the shear plane, the method of rekeying said lock apparatus comprising the steps of:

inserting into said keyway a key bit having bitting thereon adapted to position said spacer member into said top pin chamber such that the bottom surface of said spacer member is aligned with said shear plane and having a cut therein opposite said bitting of a depth corresponding to the thickness of said spacer member, said cut having a length in the direction of the keyway that exceed the dimension of said spacer member in that direction and less than the dimension of said top tumbler pin in that direction;
rotating said key bit and core in said housing to align said cut with said top pin chamber and allowing said spacer member to move out of said top pin chamber and into said cut;
rotating said key bit and core again with said spacer member captured in said cut to remove said spacer member from said pin chamber and to align said top pin chamber with said bottom pin chamber again;
and
removing said key bit from said core with said spacer member captured in said out to extract said spacer member from said lock apparatus.

2 more elements

Dependencies are inferred from the claim text.