Note: Descriptions are shown in the official language in which they were submitted.
11~558;~ .
BACKGROUND OF THE INVENTION
This invention has to do with locks, and relates
especially to locks that require two keys for their
operation, as is typically true, for example, in locks
for safe deposit boxes and similar applications.
Locks of that general type ordinarily require a
correspondingly large number of parts, making them rela-
tively expensive to manufacture and service. In par-
ticular, if each key drives a distinct and independent
set of tumblers the number of moving parts in the lock
may approach twice that required in a single-key lock.
Many presently available dual-key locks employ
two sets of pivoted tumblers each of which is indepen-
dently operated by one of the keys. In such locks the
radial length of the tumblers is severely limited by the
conventional size of the lock housing. That shorter
tumbler length increases the angle through which the
tumbler must swing for any given bit height of the key,
increasing correspondingly the range of angles at which
the key engages the various tumblers in bolt-releaslng
position. That increased range of working angles between
key and tumbler tends to reduce accuracy, limiting the
number of different key configurations that can be pro-
vided with a given number of tumblers.
It has also been proposed to construct a dual key
lock with a single stack of floating tumblers which are
engaged by the two keys at spaced positions along their
length. That concept is disclosed, with a variety of
auxiliary features, in a series of patents by Roy T.
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Ellis, of which u.s. Patent No. 3,127,759 which issued on
April 7, 1964 is illustrative. However, the tumblers of
Ellis' single stack are of complex shape and require
numerous auxiliary levers and secondary tumblers for their
operation. Moreover, the gate positions on each tumbler's
primary working edge must take account of the bit height
of both the keys. Thus, if the key combination is to be
changed by replacing one set of tumblers by a set corres-
ponding to a new pair of keys, a very large number of
different tumbler forms must be kept on hand. If key A
has six bit heights, for example, and key B has eight, the
possible key combinations may involve 48 different posi-
tions of the primary gate, all of which must be available
if all possible combinations are to be provided. In
contrast, the more conventional locks with two independent
stacks of tumblers involve only six gate configurations
for one tumbler and eight for the other, or a total of 14
species. The increased complexity and expense of the
Ellis lock in changing keys is evident.
SUMMARY OF THE INVENTION
In accordance with an aspect of the invention
there is provided a lock which includes bolt means movable
along a bolt axis between a locking position and a releas-
ing position and including fence means, at least one set
of flat tumblers, means for mounting the tumblers for
independent movement transversely of the bolt axis, a
gated blocking edge on each tumbler for cooperation with
the fence means to normally block bolt movement toward
releasing position, and key receiving means for controlling
said tumbler movement to align the gates and unblock the
bolt movement; said lock being further characterized in
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that at least a plurality o~ said tumblers include a
second gated blockinq edge facing oppositely to the first
said edge, and said plurality of tumblers have such form
that they are receivable by said mounting means in two
alternative orientations with a different one of the
blocking edges in position in each of the orientations
to cooperate with the fence means under key control.
The present invention provides dual key locks
which combine remarkable simplicity of basic form with
improved accuracy of operation. The locks of the
invention typically require no more parts, aside from the
obvious need for two key noses, than the most rudimentary
of single key locks having the same number of teeth per
key. The structure of the invention permits the keys to
position the lock tumblers with such accuracy that it
becomes feasible to provide an increased number of bit
heights within a given range of radial key dimensions.
Thus a larger number of
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combinations can be provided with a given number of key
teeth; or a given nurnber of combinations can be made avail-
able with fewer key teeth, and hence with correspondingly
fewer tumblers, leading to further reduction of the number
of parts without loss of performance.
The invention further facilitates required key
changes when that is done by replacing one or more tumblers
by tumblers having different gate positions. The invention
reduces the number of different tumblers that must be kept
on hand for carrying out such changes. Both the capital
and labor cost of key changes are thereby reduced.
Those and other advantages of the invention are
attained by employing a single stack of elongated tumblers
which are movable laterally primarily in translation and
have two gated transverse blocking edges adapted to co-
operate with respective fence lugs, typically mounted
directly on the bolt. The tumblers are laterally posi-
tioned by dual keys working at longitudinally spaced
points of the tumblers, which points are in principle
directly opposite the respective blocking edges. That
simple configuration has been found to permit each key to
act accurately and reliably to bring the corresponding
gates into alignment to release the corresponding fence
lug entirely independently of the action of the other key.
A further aspect of the present invention is the
discovery that the described independence of function of
the two keys permits the tumblers to be designed with
such symmetry that each one can be installed in the lock
in up to four alternat~ve orientations, each such orienta-
tion corresponding to a different combination of bit heights
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on the two keys. ~ore particularly, symmetry of each
tumbler with respect to a transverse axis permits two al-
ternative working orientations which are derivable from
each other by inverting the tumbler about that axis; and
two-fold tumbler symmetry, with respect to a transverse
axis and also with respect to a longitudinal axis, permits
four alternative working orientations for each tumbler.
Since each tumbler can provide four different key combi-
nations, the number of different tumbler configurations
required to make up any desired number of combinations is
typically reduced by a factor of four.
In preferred form of the invention each tumbler
comprises a generally rectangular flat plate with a trans-
verse guide slot midway of its length and two transverse
control slots equally spaced on opposite sides of the guide
slot. Both side edges of both control slots are provided
with one or more gates at selected positions. A fixed pin
is slidably received in the guide slots of all tumblers,
and two fence lugs carried by the bolt project through the
respective control slots.
The control and guide slots, and the laterally fac-
ing tumbler edges which are engaged by the two keys, are
formed symmetrically with respect to both a transverse and
a longitudinal axis. Each tumbler can then be received
in the lock with either end forward, and with either face
directed toward the cover plate. The gates, however, are
normally positioned unsymmetrically. Inversion of a
tumbler then typically alters the effective bit height
for both keys in two, or in all four, tumbler orien-
tations.
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It will be noted that in any tumbler orientationthe locking action for the forward key is always controlled
by the gate on an inner slot edge, that is~ the edge near-
est the center o~ the tumbler; while the active gate for
the rearward key is on an outer slot edge. Thus, distinct
gates cooperate with the forward and rearward keys. In-
version Or a tumbler about a longitudinal axis causes the
effective position of each active gate to be measured
from the opposite tumbler side edge.
BRIEF DESCRIPTION OF THE DRAWING
A full understanding of the invention, and of its
further objects and advantages, will be had from the
following description of certain illustrative manners of
carrying it out. The particulars of that description,
and of the accompanying drawings which form part of it,
are intended only as illustration and not as a limita-
tion upon the scope of the invention, which is defined
in the appended claims.
In the drawings:
Fig. 1 is a perspective representing an illustra-
tive lock in accordance with the invention in its normal
orientation;
Figs. 2 and 3 are vertical transverse sections on
the respective lines 2--2 and 3--3 of Fig. 4;
Fig. 4 is a vertical longitudinal section on the
lines 4--4 of Figs. 2 and 3 and showing the lock in re-
leased position;
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Fi(1. ~, is a section orres~ondin(l to Fig. 4 and
sho~ing the loc~ in locked position;
Flq. 6 is a v~rtical transverse section on the
line 6--6 o~ Fig. 5;
Fig. 7 is an exploded perspective corresponding
generally to the preceding ~igures;
Fig. 8 is a schematic perspective representing
four alternative orientations which a typical tumbler may
assume in a lock;
Fig. 9 (appearing on the same sheet of drawings
as Fig 5) is a schematic representing a typical tumbler in
its four alternative orientations, and indicating
illustrative gate positions;
Fig. 10 (appearinq on the same sheet of drawings
as Fig 5) is a schematic plan representing a modification
form of tumbler; providing distinct tumblers for each key
nose;
Fig 11 (appearing on the same sheet of drawings
as Fig 5) is a schematic plan representing a modification
of Fig. 10; and
Fig 12 is a schematic plan representing a
modified form of single t~mbler.
t
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D~SCRIPTION OF PREFERR~D EM~ODIiiE~T
The illustrative lock shown in the drawings com-
prises the case 20, typically of conventional construction
and size, with the cover plate 22. The lock is ordinarily
installed in the orientation shown in Figs. 1 to 6 with the
outer face of cover plate 22 against the inside surface of
the door that is to be locked, not explicitly shown. The
mounting posts at the case corners facilitate such mounting,
as by screws in the bores 21. Since the cover plate is re-
tained securely when the lock is so mounted, only the singlescrew 23 is typically provided for holding the cover when
the lock is removed, as for servicing. For clarity of descrip-
tion, the lock will be assumed to be in its normal orientation,
but without implying any limitation to such use.
Case 20 includes the rectangular back wall 24, the
upper and lower side walls 25 and 26, the rearward end wall
27 and the forward end wall 28. The bolt 3O is mounted in
case 20 for sliding movement along the bolt axis 31, which
is parallel to the length of the case. The bolt is typically
20 guided in that movement by case back wall 24, by sliding fit
of its thickened forward working end 32 in the rectangular
aperture 29 in case front wall 28, and by the pin 34 which
projects rigidly and perpendicularly from case back wall 24
and is slidingly received in the longitudinal slot 36 in the
25 bolt. That slot defines the range of bolt movement between
its forward, projecting locking position (Figs. 1 and 5) and
its rearward, retracted releasing position (Fig. 4). The
bolt is provided with the iwo up~tanding fence lugs 38 and 39,
which are typically of like form and are spaced longitudinally
30 Or the bolt forward and rearward, respectively, of guide slot 36.
11~558Z
The tumblers 40 are slidably mounted in a stack
between tne fl2t upper face of bolt 30 and the inner face
of cover plate 22. They are guided in thelr sliding move-
ment by pin 34, which is slidingly received in the trans-
verse slot 42 of each tumbler. Guide slot 42 is perpen-
dicular to the longitudinal tum~er axis 41 and positively
defines the position of each tumbler along bolt axis 31.
The tumblers also have two transverse control slots 44 and
45, equally spaced forwardly and rearwardly, respectively,
from guide slot 42. In locking position of the bolt, as
in Fig. 5, tumbler control slots 44 and 45 freely receive
the respective bolt fence lugs 38 and 39, normally blocking
bolt movement toward releasing position.
The two key noses 50 and 52 are mounted in case 20
5 laterally adjacent the lower edge of the tumbler stack and
mutually spaced longitudinally of the tumblers. The key
noses typically comprise the core members 54 and 56, which
are journaled on the key axes 51 and 53 in aligned bores in
back wall 24 and in cover plate 22. The cores project
through the cover plate within the protective collars 65,
and are thus accessible ~rom outside the door on which the
lock is mounted. The cores are slotted in conventional
manner to receive their respective keys 55 and 57, which
are rotatable with the nose cores between generally hori-
25 zontal bolt locking positions (Fig. 5) and generallyvertical bolt releasing positions (Fig. 4).
Tumblers 40 are individually biased laterally to-
ward the two key noses by spring means which may be of any
suitable type. As illustratively shown, the unitary spring
30 60 comprises the base portion 62, typically mounted between
_g _
11~558~2
top case wall 25 and the fixed post 61, and the individual
spring arms 64. Each arm is provided with a tumbler-
engaging finger structure 66 of U-section adapted to embrace
the upper edge of a tumbler approximately midway of its
length, where the tumbler plate is thinned by coining 67, as
shown in Fig. 5. The resulting downward force on each tum-
bler maintains its lower edge in light contact with both
key noses when the keys are in bolt locking positions. As
the keys are rotated clockwise to bolt releasing positions
each tumbler is lifted by the key teeth to a definite ele-
vated position, slightly compressing the respective spring
arms.
Contro] slots 44 and 45 of each tumbler are pro-
vided on their rearward edges 46 and 47 with gate apertures
48 and 49. Those gates are just wide enough to receive the
fence lugs, and are positioned laterally of each tumbler
in accordance with the various bit heights of the corre-
sponding key. Clockwise rotation of both keys to their bolt
releasing positions thus lifts each of the tumblers a dis-
tance just sufficient to align the gates with the respectivefence lugs 38 and 39. The bolt is thus released from the
blocking action of the tumblers at both the forward and
rearward control slots 44 and 45.
One of the two key noses, shown typically as for-
ward nose 50, is provided with a lever 70 for engaging the
bolt faces 71 and 72 to drive bolt 30 between its locking
and releasing positions in response to rotation of the
associated key. As illustratively shown, the bolt releasing
face 71 is engaged by lever 70 as key 55 reaches its bolt
releasing position. Continued key rotation through a small
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11~558~
angle dri~es the bolt to its fully retracted position,
defined by pin 34. Counterclockwise key rotation then
causes lever 70 to engage the second bolt drive face 72,
driving the bolt forward. The lever slips off face 72 as
the bolt reaches its locking position. The key is then free
to return to its normal locked position, with lever 70 oppo-
site the arcuate clearance surface 73 on the bolt, posi-
tively blocking the latter from release movement.
The key nose with which bolt drive lever 70 is
associated is normally operated to releasing position only
after the other key nose has been so operated. Thus, in
the present instance, key 57 is operated first. Its bolt
locking and releasing positions are defined by the respec-
tive stops 75 and 76. Bolt locking and releasing positions
f key 55 are defined via lever 70 by the stop 78 and by
the action of pin 34 in limiting bolt movement.
The longitudinal positions of the two key noses
along bolt axis 31 are such that the respective keys en-
gage driving surfaces on the lower tumbler edges at points
approximately opposite the respective tumbler control slots
44 and 45. Stating the preferred relation more precisely,
each key axis 51 is directly in line with the normal posi-
tion of the rearward, or active, edge of the associated
control slot 44 or 45. The point of contact of each key on
the lower tumbler edge when in bolt releasing position is
then also approximately aligned with that active slot edge.
A slight deviation from that latter relation may be caused
by inclination of the tumbler when the bit height is greater
for one key than for the other, as illustrated in Fig. 4.
However, such inclination is ln general as likely to be in
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1~5582
one direction as the cther, and its maxirnum value ls
limited by the relatlvely wide separation of the two key
noses so that in practice its erfect :Ls completely
negligible.
The defined relative location of the key noses has
the important result that rotation of each key to bolt
releasing position aligns the corresponding tumbler gates
independently of any action by the other key. Thus, not
only is the bolt fully released by operation of both keys,
but operation of either key alone completes the releasing
action to that key, and that action is not disturbed by
later operation of the other key.
That independence of action by the two keys may be
visualized more precisely from the detailed nature of the
tumbler movement when one key is operated. The resulting
level change at the operated key causes movement that is
limited by support of the tumbler on the stationary key
and by guiding action of pin 34 in tumbler guide slot 42.
The resulting tumbler movement is rotation about a center
of rotation which shifts with the movement but is always
close to the gated edge for the stationary key. The pre-
cise locus of the center of rotation at each moment is the
intersection of a line perpendicular to slot 42 at pin 34
and a line perpendicular to the tumbler edge at the
stationary key. Since in practice that center of rotation
is always virtually at the control slot edge, the tumbler
rotation due to one key can cause no appreciable variation
in gate level at the other key, thus insuring that each key
functions independently of the other.
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An advanta~e cr meeting that independence condi-
tion strictly is that the lock operates in an unusually
precise manner with a linear one-to-one relationship
between the various bit heights of each key and the spacings
of the corresponding gates along the blocking edge of the
tumbler. Thus, the spacing between gate positions is
directly equal to the difference between the corresponding
key bit heights. That equality has been found to improve
the accuracy of operation sufficiently to permit a reduction
of the bit intervals. A given available range of bit heights
can then accommodate a larger number of distinct bit levels
and provide a correspondingly increased number of key
combinations.
The attainment of independent key operation with
a single set of floating tumblers further permits each
tumbler to assume multiple orientations in the lock, pro-
viding a correspondingly increased number of key combina-
tions. That concept is illustrated in Fig. 9 for a tumbler
with typical gate configuration. ~our different tumbler
orientations are designated A, B, C and D. The tumbler
can be shifted from one orientation to an adjacent one by
inverting it about the horizontal axis 90 or the vertical
axis 92. A typical configuration of gates is shown, selected
from six equally spaced gate positions for the left key,
designated 1 to 6, and three gate positions for the right
key, designated a, b and c. The total range of available gate
positions is indicated by the lines 94 and 95 for the res-
pective keys, considerably exaggerated for clarity of illus-
tration. The provision of more bit positions for one key
than the other may be useful, for example, l~hen many differ-
ent subscribers' keys are required, but only a smaller number
OI' guard keys.
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As seen in tu~bler orientation A, the two inner
gates 96 and 97, w}lich relate to the left key, appear at
positions 1 and 3, whereas the two outer gates g8 and 99
which relate to the right key, appear at positions b and
c. The operative gates for the respective left and right
keys are then gate 96 in position i and gate 99 in position
c. Those positions are typically marked on the face of the
tumbler in some definite relation to the respective gates,
as indicated in the figure.
Inversion of the tumbler about axis 90 to orienta-
tion B shifts each of the operative gates 96 and 99 to the
opposite side of the longitudinal axis of tumbler symmetry
41. The gates then assume the respective positions 6 and a,
which are also marked on the tumbler face. Inversion of
the tumbler about vertical axis 92 from A to C, on the other
hand, moves gates 97 and 98 into operative positions for the
left and right keys, respectively. The gate positions at C
are thus 3 for the left key and b for the right key. The
further inversion fr~m C to D shifts operative gate 97 for
the left key to the symmetrically opposite position 4; but
gate 98 for the right key, being directly on axis 41, is
not altered by the inversion. Orientation D can obviously
be reached via B as well as via C; or directly from A by
tumbler rotation in its plane about the point 91.
The invariance of gate 98 with respect to inversion
between positions C and D has practical value when it is
desired to change the left key without changing the right
one, as when a subscribers' key is changed and a bank
control key is held constant, for example. Such invariance
for a gate position off the axis of symmetry may be obtained
by providing the blocking edge with dual gates, symmetrically
~l~ccd ~ , r~c~ v ~h~ aXl~.
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11'?~55~
.;ith each tumbler marked clearly with the co:~ination
of key bit levels to which it corresponds in each of its
four orientations, as typically indicated in Fig. 9, for
example, the proper tumblers can readily be selected from
a suitable stock to assemble a tumbler stack corresponding
to any given pair of keys; or keys can readily be cut to
correspond to any given stack of tumblers. For servicing
any required number of different key combinations, the
invention thus reduces by a factor of approximately four
the number of distinct varieties of tumbler that must be
kept in stock.
Some of the above described advantages of the inven-
tion are attainable with separate tumblers for each key.
Although more items are then required for servicing â given
number of key combinations, the length of each tumbler is
typically reduced, which may sometimes be advantageous.
As indicated illustratively in Figs. 10 and 11, each tumbler
of the previous embodiment may be replaced by two generally
identical units, with sùitable means for guiding their
lateral movement. The tumbler units are all generally
identical in shape, each one having two distinct gated
blocking edges with the gates typically positioned differ-
ently along the two edges. Each tumbler is then usable
alternatively for cooperating with either one of the two
key noses, one blocking edge being adapted for cooperating
with one key nose, the other blocking edge with the other
key nose.
In Fig. 10 each of the smaller tumblers 140 is
guided by the pair of fixed pins 106 or 108 working in a
slngle transverse tumbler guide slot 110. Since the
~1~5582
movement is then strictly translational, the key noses
50a and 52a may be placed at any convenient longitudinal
position, preferably close enough to the guide slots to
avoid any tendency of the guide pins to bind. A single
spring element 160 may be arranged to bias all the tumblers
if desired.
In Fig. 11 the two stacks of tumblers 140a are
pivoted on the respective fixed pins 112 and 114 for swing-
ing movement in response to the bias springs 60b and the
respective key noses 50b and 52b. Control slots 144a are
preferably curved approximately about the pivot pin as a
center, and the keys engage driving edges on the tumblers
that are preferably approximately radial with respect to
the pivots. Both tumbler stacks can be pivoted on the same
pin, if preferred, with suitable provision for interleaving,
as by thinning the tumblers near the pivot.
In both Figs. 11 and 12 the tumblers are preferably
symmetrical with respect to individual longitudinal axes
141 or 141a. They can then be inverted about that axis;
and are also insertable in the lock in position to control
either one of the two fence lugs. Thus each tumbler is
usable in four alternative orientations, and is typically
labeled, as in the general manner previously described, to
indicate the gate positions that are active in each orienta-
tion. As in the first described embodiment lug 38 is côn-
trolled only by the gates 196 on the inner side edge of the
control slot, lug 39 only by the gates 198 on the outer
side edge.
Fig. 12 illustrates somewhat schematically a further
modification of the first described embodiment. As before~ -
.. .
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ll~S~82
tu~blers 40a are guided by the fixed pin 34 working in
the transverse guide slots 42, and the bolt movement is
controlled by the fence lugs 38 and 39 which cooperate with
gated blocking edges on the tumblers. The gates, however,
in the present structure rnay be described as being formed
in the outer and inner edges of the two transverse bridge
portions 100 and 102 of the tumblers, rather than in the
inner and outer side edges of the respective control slots
44 and 45, as before. From another viewpoint, the gates
49, which control fence lug 39, are formed in the outer
side edges 47 of the control slots, as before, but the gates
48a for lug 38 are formed in the end edges 104 of the tumb-
ler. Thus the inner side edges 46 of the control slots are
free of their previous function, and can be given any con-
venient shape.
Key noses for tumblers 40a are preferably placed inthe previously described relation to their respective gated
blocking edges; that is, with key nose 50c i~ line with the
forward or lefthand end 104 of the tumbler, and with key nose
52c in line with the rearward or righthand side edge 47 of
control slot 45. The lateral sides of the tumblers may be
extended beyond thedrive edges 104, as indicated typically
at 105, to insure adequate driving contact for the key in
nose 50c. Operation of the modified tumblers is then in
principle as has been described. The embodiments of Figs.
10 and 11 may be modified in corresponding manner, as will
be evident without specific illustration.
It will be understood that many further modifica-
tions may be made in the illustrative configurations de-
scribed herein without departing from the proper scope of
...
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1~45582
the invention. For example, it is soMetimes convenient to
m-~ke all required key changes by inverting certain ones of
the tumblers, retaining other tumblers always in a prede-
termined orientation in the lock. Under that condition
the tumblers that are not inverted may be of somewhat
simplified form, as by omitting gates and accurately fin-
ished driving edges t}~at are not needed. Under that condi-
tion, the tumblers that are not to be inverted are prefer-
ably arranged at the bottom of the stack.
As a further example, it is sometimes useful to pro-
vide single key locks which are interchangeable with dual
key locks of a particular design. The structures already
described are well adapted for that purpose. To convert
the present locks to single key operation key nose 52 and
its collar 65 (Fig. 1) can be omitted, for example, together~
with fence lug 39. In embodiments based on Figs. 10 and 11
the rearward tumbler stack is also omitted. In the forms
of the invention ~ith a single tumbler stack, a fixed pin
is typically substituted for the omitted nose core to sup-
port all the tumblers at their rearward ends at any selecteduniform level. Operation of a key in nose 50 then aligns
the corresponding gates correctly, unblocking fence lug 38
and releasing the bolt despite absence of the second key.
