Nova Patents
US3597948A

Lock cylinder assembly

Abstract

This record has no abstract on file.

US3597948A, drawing sheet 1
Sheet 1 of 2

Term

Term ended

Expired 10 August 1988, 38.1 years ago.

  1. Priority and filed
  2. Granted
  3. Expired
  4. Today

1 claim: 1 independent, 0 dependent

  1. 1
    I claim:1. A lock cylinder assembly including a core mounting a plurality of key-locatable tumblers and defining a slot, a key 40 having a flattened bitted portion receivable within the slot wherein the lateral sides of the bitted portion include grooves for receiving ribs fixed with respect to the core and extending axially thereof adjacent the opening of the slot, an additional lateral rib fixed with respect to the core adjacent the end of 45 the slot remote from the opening thereof, the additional lateral rib extending axially of the core for a limited distance with respect to the bitted portion when inserted within the slot, and an additional lateral groove at the free end of the bitted portion extending for such limited distance and receiv50 ing the additional lateral rib when the bitted portion is inserted within the slot, the additional lateral rib and the additional lateral groove being unaligned with any rib or groove adjacent the opening of the slot. LOCK CYLINDER ASSEMBLY This invention relates to lock cylinder assemblies and more particularly to a lock cylinder assembly having an increased number of lock combinations. The number of lock combinations which normally can be obtained from a tumbler-type lock is affected by the number of tumblers included in the lock. Generally the number of theoretical combinations is much greater than the number of usable combinations. In order to increase the number of combinations without increasing the number of tumblers, it is conventional to provide a ribbed gate in the core and grooves in the key which must mate with the ribs of the gate before the key can be inserted in the core to properly locate the tumblers in their unlocked position. Due to space and manufacturing limitations, the number of such ribs and grooves is limited so that the increase in number of lock combinations is likewise limited. The lock cylinder assembly of this invention increases the number of lock combinations by having an additional rib within the core remote from the ribbed gate and receiving an additional groove in the leading end of the bitted portion of the key when the key is fully inserted within the core. The core rib is unaligned with any other core rib and likewise the key groove is unaligned with any other key groove so that only a properly grooved key can be fully inserted in order to locate the tumblers in their unlocked position. By varying the location of the interfitting additional rib and groove, in combination with varying the location of the ribs on the gate and grooves on the key, an increase in the number of possible lock combinations can be obtained within the normal manufacturing and space limitations. By locating the additional rib remote from the gate and by locating the groove in the leading end of the bitted portion of the key, it is impossible for an improperly coded key to move all of the tumblers to unlocked position by partial insertion of the key. The primary object of this invention is to provide a lock cylinder assembly having an increased number of lock combinations. Another object of this invention is to provide a lock cylinder assembly having an additional rib within the core remote from the gate and receiving an additional groove in the leading end of the bitted portion of the key, both unaligned with any other ribs and grooves, to thereby provide an increase in the number of usable lock combinations. These and other objects of the invention will be readily apparent from the following specification and drawings wherein: FIG. 1 is a partially cutaway view of a lock cylinder assembly according to this invention;FIG. 2 is a sectional view taken generally along the plane indicated by line 2-2 of FIG. 1;FIG. 3 is a view taken generally along the plane indicated by line 3-3 of FIG. 1;and FIG. 4 is a view similar to FIG. 1 showing the assembly with the key withdrawn.