U.S. patent number 3,768,284 [Application Number 05/267,474] was granted by the patent office on 1973-10-30 for maximum security lock assemblies.
Invention is credited to Robert W. Kent, Jr., Robert W. Kent.
United States Patent |
3,768,284 |
Kent , et al. |
October 30, 1973 |
MAXIMUM SECURITY LOCK ASSEMBLIES
Abstract
A maximum security lock assembly adapted for mounting on a door
within a door frame, comprised of an armor plate of tool-resistant
alloy steel having an integral frusto-conical protrusion extending
outwardly therefrom, on the interior of which is fixed a pin
tumbler lock with a cylindrical plug or core which is released for
rotary movement upon the insertion of the properly fitted key into
its keyhole. An oscillating crank connected to the rotary plug
actuates a bolt mechanism which is selectively engageable with
apertured lugs on a strike on the door frame which extend into the
field of movement of the locking bolts when the door is in closed
position. An opening of restricted area in the outer wall of said
protrusion permits the insertion of said key into the keyhole of
the lock and the rotation thereof while leaving concealed the main
outer face of the lock and especially the portions thereof most
vulnerable to picking and drilling of the lock assembly. The screw
and bolt fasteners for the complete lock assembly including the
components thereof, are hidden, and a shield of tool-resistant
alloy surrounds the connections from the lock to the bolt actuating
mechanism to prevent the disabling of the locking assembly at this
portion thereof. The armor plate and protrusion extending therefrom
which is resistant to the operations of drills, wrenches and jimmys
thereon may be duplicated on the inner side of the door to secure
the lock assembly against operation without a proper key on the
inner side of the door as well as on the exterior thereof.
Inventors: |
Kent; Robert W. (Miami Beach,
FL), Kent, Jr.; Robert W. (Andover, MA) |
Family
ID: |
23018931 |
Appl.
No.: |
05/267,474 |
Filed: |
June 29, 1972 |
Current U.S.
Class: |
70/104;
70/DIG.60; 70/406; 70/417; 70/418; 70/448 |
Current CPC
Class: |
E05B
15/1614 (20130101); Y10T 70/7864 (20150401); Y10T
70/7921 (20150401); Y10T 70/7927 (20150401); Y10S
70/60 (20130101); Y10T 70/5212 (20150401); Y10T
70/8459 (20150401) |
Current International
Class: |
E05B
15/16 (20060101); E05B 15/00 (20060101); E05b
009/04 () |
Field of
Search: |
;70/103,104,134,393,405,406,417,448,DIG.57,DIG.60 ;292/340 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Craig, Jr.; Albert G.
Claims
We claim:
1. A burglar-proof lock assembly for mounting on a door within a
door frame having a strike mounted thereon provided with a pair of
spaced apertured lugs projecting therefrom, comprising
a. a lock case adapted to be mounted on said door provided with
slots in alignment with said lugs for reception of said lugs in the
closed condition of the door within said frame,
b. a reciprocable locking bolt assembly in said case comprising a
pair of coaxially disposed bolts for alternative engagement with
the apertures in said lugs to interlock the door with the frame or
disengagement from said apertures to permit the separation of said
door from said frame,
c. an actuating mechanism within said case connected to said
bolts,
d. an oscillating crank for operating said last-mentioned mechanism
to control the positioning of said bolts relative to said slots in
said lock case,
e. a cylinder lock comprising an outer barrel containing a
plurality of longitudinally arranged pin tumbler units, and an
inner core having a keyhole at the outer end of said barrel and a
tailpiece at the inner end thereof extending between said core and
said oscillating crank,
f. a tool-resistant armor-plate displaced from said casing for
supporting said cylinder lock and concealing said cylinder lock and
tailpiece, and
g. a frusto-conical protrusion on the front of said armor-plate for
protecting said lock against tampering and destruction, said
armor-plate and protrusion having only a single opening of
restrictd area constituted by a slot of restricted area, sufficient
for the insertion of the shaft of the key adapted to be inserted in
said keyhole and the rotation thereof in said core while covering
the outer face of the cylinder lock at the points thereof
vulnerable to the entry of drills or other lock-picking and
tampering tools.
2. A device as set forth in claim 1, including a second armor-plate
covering the side of said lock case remote from said
first-mentioned armor-plate.
3. A device as set forth in claim 2, including screw fastening
means for the strike on the door frame adapted to extend into the
heavy timbers supporting said door frame, said fastening means
being concealed by said lock case in the closed condition of the
door.
4. A device as set forth in claim 3, wherein said screw fastening
means comprises a plurality of wood screws ranging upwardly from
two and one-half inches in length extending into the framing
timbers from two transverse directions.
5. A device as set forth in claim 1, including a protective
enclosure of tool-resistant metal between said armor-plate and lock
case surrounding said cylinder lock and tailpiece.
6. A device as set forth in claim 5, wherein said protective
enclosure comprises one cylindrical tube having one end projecting
from the interior of said protrusion and a second cylindrical tube,
of slightly different diameter from said first tube, having one end
projecting from said lock case, with the opposite free end of each
cylindrical tube disposed in overlapping telescopic relation.
7. A device as set forth in claim 1, including means for
integrating said armor-plate with said lock case comprising a
plurality of bolts integrally connected to the inner face of said
armor-plate and extending through the door into said lock case,
with fastening nuts on said bolts acting against the inner wall of
said lock case.
8. A device as set forth in claim 3, including means for
integrating said first-mentioned armor-plate with said lock case
comprising a plurality of bolts integrally connected to the inner
face of said armor-plate and extending through the door into said
lock case, with fastening nuts on said bolts acting against the
inner wall of said lock case, said lock case and second armor-plate
extending beyond the area of attachment between said first
armor-plate and lock case for engagement with the lugs of the
strike in the closed condition of the door, in which position said
screw fastening means are covered by said case.
9. A device as set forth in claim 8, wherein said lock case is of
rectangular prismatic section defined by four rectangular walls
projecting from the inner wall of said case, and said second
armor-plate is detachably connected to the outer edges of said
walls.
10. A device as set forth in claim 9, wherein the upper and lower
walls are provided with guide tracks at the outer edges thereof and
reentrant flanges on the upper and lower edges of said second
armor-plate for engaging said guide tracks for slidable movement
thereon.
11. A device as set forth in claim 10, including a J-shaped
extension on said second armor-plate for encasing the outer lateral
wall of said case and the exterior of the inner wall of said case
adjacent thereto, and fastening bolts between the latter and said
extension adjacent the free extremity thereof for fixing said
second armor-plate in closed position on said case, said
last-mentioned fastening bolts also being concealed at said
strike.
12. A device as set forth in claim 11, wherein said J-shaped
extension is provided with slots complementing the slots in the
lock case for receiving the lugs of the strike in the closed
condition of the door within the frame.
13. A device as set forth in claim 7, wherein the displacement of
the tool-resistant armor-plate from said casing corresponds to the
thickness of the door through which extend said plurality of bolts
interconnecting said armor-plate and said lock case.
14. A burglar-proof lock assembly for mounting on an inwardly
opening door within a door frame having a strike mounted thereon
provided with a pair of spaced apertured lugs projecting inwardly
therefrom, comprising
a. a lock case adapted to be mounted on the inner side of said door
provided with slots in alignment with said lugs for reception of
said lugs in the closed condition of the door within said
frame,
b. a reciprocable locking bolt assembly in said case comprising a
pair of coaxially disposed bolts for alternative engagement with
the apertures in said lugs to interlock the door with the frame or
disengagement from said apertures to permit the separation of said
door from said frame,
c. an actuating mechanism within said case connected to said
bolts,
d. an oscillating crank for operating said last-mentioned mechanism
to control the positioning of said bolts relative to said slots in
said lock case,
e. a cylinder lock comprising an outer barrel containing a
plurality of longitudinally arranged pin tumbler units, and an
inner core having a keyhole at the outer end of said barrel and a
tailpiece at the inner end thereof extending between said core and
said oscillating crank,
f. a tool-resistant armor-plate displaced outwardly from said
casing a distance corresponding substantially to the thickness of
the door for supporting said cylinder lock and concealing said
cylinder lock and tailpiece,
g. a frusto-conical protrusion on the front of said armor-plate for
protecting said lock against tampering and destruction, said
armor-plate and protrusion having only a single opening of
restricted area constituted by a slot of restricted area,
sufficient for the insertion of the shaft of the key adapted to be
inserted in said keyhole and the rotation thereof in said core
while covering the outer face of the cylinder lock at the points
thereof vulnerable to the entry of drills or other lock-picking and
tampering tools,
h. a second tool-resistant armor-plate covering the side of said
lock case remote from said first-mentioned armor-plate, and
i. a mechanical actuator extending through said second armor-plate
and terminating within said lock case in a second rotary crank for
operating said first-mentioned actuating mechanism.
15. A device as set forth in claim 1, applied to an inwardly
opening door, including
a. a second tool-resistant armor-plate covering the side of said
lock case remote from said first-mentioned armor-plate,
b. a chamber with a frusto-conical exterior in said second
armor-plate on the inner face of the door in substantial alignment
with said frusto-conical protrusion in said first-mentioned
armor-plate,
c. an indoor cylinder lock comprising an outer barrel containing a
plurality of longitudinally arranged pin tumbler units and an inner
core having a keyhole at the exposed end of said barrel and an
oscillating crank connected to the inner end thereof for selective
engagement with said bolt-actuating mechanism,
d. said second armor plate having a keyhole slot of restricted area
in the frusto-conical exterior of said chamber, said area being
sufficient for the insertion of the shaft of the key adapted to be
inserted in said keyhole on the inner face of the door, and the
rotation thereof in said core, while covering the outer face of
said last-mentioned cylinder lock at the points thereof vulnerable
to the entry of drills or other lock-picking and tampering
tools.
16. A device as set forth in claim 15, wherein the pin tumbler
units in the first-mentioned cylinder lock range from six to twelve
in order to render the lock less vulnerable to picking tools.
17. A device as set forth in claim 15, wherein the pin tumbler
units in both of said cylinder locks range from six to twelve in
order to render the lock less vulnerable to picking tools.
18. A device as set forth in claim 1, wherein said cylinder lock is
provided with a row of auxiliary pin tumbler units displaced
angularly on each side of said first-mentioned longitudinally
arranged pin tumbler units.
19. A device as set forth in claim 18, wherein the pin tumbler
units in the first-mentioned group range from six to twelve in
order to render the lock less vulnerable to picking tools, and the
auxiliary pin tumbler units in the angularly displaced rows are
diminished by at least one, at least at one end of each row.
20. A device as set forth in claim 1, wherein the outer end of said
cylinder lock is affixed within the interior of said protrusion
rearwardly of the front face of the latter to form a space
therebetween, at least one apertured plate therebetween being of
special alloyed metal to supplement the protection against
tampering with the lock.
21. A device as set forth in claim 1, wherein the key-opening in
said armor-plate is restricted substantially to the keyhole in the
core of the cylinder lock, leaving unexposed the areas adjacent to
the core of special vulnerability to the destruction of the pin
tumbler units by drilling or prying.
22. A device as set forth in claim 21, including a key bit with
undercut indentations adjacent to the hand grip of the key to
accommodate the outer face of said protrusion in the course of
rotating the key.
23. A device as set forth in claim 22, wherein the outer face of
said core of the lock is provided with sockets for receiving
propulsion pins on the handgrip of the key to reenforce the
coupling therebetween and to compensate for the undercut
indentations in the key.
Description
This invention relates to a substantially burglar-proof lock
assembly for mounting on the doors of residences, warehouses,
industrial buildings, or any other enclosures, in order to prevent
unlawful entry therethrough.
It is the object of the present invention to provide a door closure
which is substantially burglar-proof by incorporating structural
features in the lock assembly on the door in cooperation with a
ruggedly mounted strike on the frame.
It is another object of the invention to provide lock components
and to arrange for the disposition of them, which renders virtually
impossible, or at least extremely difficult, for the lock to be
picked, "jimmyed," multilated or destroyed with tools such as
drills, wrenches, pliers, crowbars and the like, and which, upon
simple inspection, would discourage a potential burglar from
tapering with the lock.
It is a further object of the invention to provide for a lock
assembly which may be produced economically, which is rugged in
construction and easy to install, so that the wide adoption of such
would have a salutary effect on the reduction of burglaries and the
attendant high costs to the individual victims as well as the
general public, which are occasioned thereby.
Other objects and purposes will appear from the detailed
description of the invention following hereinafter, taken in
conjunction with the accompanying drawings, wherein
FIG. 1 is a front elevation of the lock assembly mounted on a door
hinged within a door frame viewed from the interior thereof;
FIG. 2 is a horizontal sectional view along line 2--2 of FIG.
1;
FIG. 3 is a front elevation of the lock assembly mounted on the
door viewed from the exterior thereof along line 3--3 of FIG.
2;
FIG. 4 is a perspective view of the strike plate mounted on the
door frame opposite the door hinges, parts of which strike plate
are shown in FIGS. 1 and 2;
FIG. 5 is a vertical sectional view along line 5--5 of FIG. 1;
FIG. 6 is an enlarged view of the outer face of the lock assembly
in the vicinity of the keyhole, along line 6--6 of FIG. 5;
FIG. 7 is a view of the outer face of the cylinder lock along line
7--7 of FIG. 5;
FIG. 8 is a front view of the key which is adapted to be inserted
in the keyhole shown in FIG. 6;
FIG. 9 is a top view of the key shown in FIG. 8; and
FIG. 10 is an end view of FIG. 9.
In the drawings is shown a door D mounted within a frame F,F'
which, for the purpose of illustration, is shown as an inside
opening door mounted on hinges H on one side thereof having the
lock assembly C mounted on the other side thereof cooperating with
the strike S mounted on the stile F of the frame. As explained
below, the lock assembly also may be applied to outside opening
doors as well as to sliding doors.
The drawings illustrate a maximum security lock assembly which
requires the operation by a key on both the outside and inside of a
door closure. Thus, in FIG. 2 the lock assembly comprises an armor
plate 10 having a frusto-conical protrusion extending outwardly
therefrom and terminating in the flat external portion 12 in which
is disposed the keyhole opening 13, described in greater detail
below.
The armor plate 10, of any suitable tool-resistant steel alloy, is
mounted on the outside face of the door by means of a plurality of
bolts 14 which are affixed by welding, brazing, soldering, etc. to
the internal face of the armor plate 10 and which extend through
bored openings 14' in the door into the interior of lock casing C,
which is mounted on the internal face of the door as shown in FIGS.
1, 2 and 5.
A cylinder lock 15, containing a plurality of longitudinally
arranged pin tumbler units 16, is fastened on the interior of the
frusto-conical protrustion 11 by bolting with the usual pair of
bolts, welding, brazing, soldering, etc. No evidence of the
mounting appears on the outer face of the protrusion. This is
accomplished by affixing the usual pair of fastening bolts of the
type disclosed in U.S. Pat. No. 1,579,139, Mar. 30, 1926, to the
inner face of the flat external portion 12 of the frusto-conical
protrustion similarly to the bolts 14 on the inner face of the
armor plate. The cylinder lock with diametrally opposed bores are
slid onto the fastening bolts, and thereafter locking nuts, with or
without additional lock washers, are applied to the free ends of
the fastening bolts to secure the cylinder lock tightly against the
inner face of the armor plate and protrustion therein or against
spacers 61. Lock constructions of this type are well known in the
art, as exemplified by U.S. Pat. No. 1,967,042, July 17, 1934. Such
locks are generally provided with a rotary plug or core 17
extending therethrough, which, upon the insertion of a properly
fitted key into the keyhole slot at the outer end of the plug or
core, results in the release of the latter for rotary movement. An
additional measure of security may be attained by the use of
cylinder locks of multiple rows of pin tumblers of the type
disclosed in U.S. Pat. Nos. 1,707,922, Apr. 2, 1929, and 2,836,973,
June 3, 1958. In such locks, the pin tumbler units 16 are
supplemented by additional pins 16a and 16b of pin tumbler units
disposed in planes at an angle of approximately 30.degree. relative
to the plane containing the main operating drivers 96 with their
compression springs 96', (FIGS. 5 and 7). The back-up drivers 97
and 98, with their compression springs 97' and 98', respectively,
in the rows flanking the drivers 96, render impossible a complete
turning of the lock plug 17 when the lock is picked, since upon the
turning of the plug 20.degree. to 30.degree. either way, the
back-up tumblers shoot into the plug holes and re-lock the plug.
Ten back-up tumblers in each back-up row are sufficient when twelve
are disposed in the row of main drivers in alignment with the key
slot, as shown in FIG. 5. The proper key cannot be pulled out at
either of the radial points because there is no hole for the
reception of the inner pair at these points. If anyone were to
succeed in picking the cylinder plug, either to the left or right,
the turning of the plug approximately 30.degree. would result in
the outer-tumblers dropping into the plug, thus locking the
cylinder in an 11 o'clock or 1 o'clock position, and requiring that
it be picked all over again to release the plug.
A tongue or tailpiece 18, generally of steel alloy of flat
rectangular cross-section, is connected to the inner end of the
core to impart rotary movement to an oscillating crank 19 at the
outer end of the tailpiece 18 for actuating the lock mechanism
described in greater detail below.
The inclination of the frusto-conical portion 11 of the armor plate
10 is such, that wrenches, pliers and similar tools are incapable
of grasping the portion 11, so that wrenching the lock from the
assembly is rendered impossible. This inclination may be of the
order of 45.degree. relative to the plane of plate 10. Furthermore,
the number of pin tumbler units 16 within the lock may be increased
to as many as twelve, as described above, in order to render the
picking thereof more difficult than is the case with conventional
locks of this type which generally are provided with five or six
pin tumbler units, and the security of the lock may be enhanced by
using pins of drill-proof steel alloy. Also, the outer face 15' of
the lock is housed within the protrusion 11 and, because of the
frusto-conical formation, is displaced from the exterior thereof,
so that the manipulation of a lock-picking tool is rendered
difficult. The spacing of the outer face of the cylinder lock
within the protrusion may be controlled easily by the provision of
washers on the above-mentioned conventional pair of fastening bolts
which, of course, are accessible only from the inner face of the
armor plate. The gap between the end of the lock and the keyhole
opening in the outer plate 12 may be filled with one or more layers
61 of tool-resistant steel or other alloys, so that the drilling of
the lock and/or entry of tools thereinto are effectively
blocked.
The mounting of the cylinder lock on the interior of the protrusion
11 by bolting, soldering or welding, eliminates the mounting
collars which are usually used for the mounting of such and which
provide a point of entry for prying and jimmy tools. Also, the
absence of any mounting screws or bolts on the outer face of the
armor plate 10 renders impossible the "jimmying" of the lock at
these points.
The lock case C mounted on the internal side of the door is affixed
thereto by means of the bolts 14 which extend through the door D
and through openings 24 in the supporting plate 60 and rear wall 30
of lock case C, and which are tightly fastened together by means of
nuts 28. The metallic case C may be formed of square or rectangular
outline having horizontal lateral walls 31,31' projecting from the
upper edges of back wall 30 and vertical lateral walls 32,32'
extending from the back wall 30 and forming a continuous boundary
thereon in conjunction with walls 31,31' .
The lock case contains a bolt actuating mechanism comprising plate
33 which is vertically reciprocable within the case adjacent to the
back wall 30, and which mechanism terminates in coaxially disposed
bolts 35,35' which are vertically movable adjacent rectangular
slots 36 in the case which overlie the door frame F (FIGS. 2 and
3).
The vertical movements of the bolts 35, 35' from their alternate
positions into and out of intersecting relationship with the slots,
are controlled by the actuating mechanism 33 which includes camming
surfaces which are responsive to the oscillating movements of the
crank 19, which is rotated by the tailpiece 18 connected to the
inner end of the plug 17 of the cylinder lock 15. This actuating
mechanism does not constitute part of the instant invention and
such may assume any desired form known in the art. U.S. Pat. Nos.
1,162,406, Nov. 30, 1915; 1,215,470, Feb. 13, 1917; 1,924,627, Aug.
29, 1933; and 2,042,026, May 26, 1936, are illustrative of many in
the art which disclose such mechanisms.
A detachable cover 20 is provided for the open face of the lock
case C defined by the free edges of walls 31,31' , 32 and 32'. A
lateral wall 40 extends rearwardly from one edge of cover 20
adjacent to wall 32 and is bent inwardly to form wall portion 41
against the exterior face of back wall 30 which overlies the door
frame F. Rectangular slots 36 in wall portion 41 are coincident
with slots of the same dimensions in wall 30 and countersunk
openings in wall 41 receive flat-headed screws 66 for fastening the
cover 20 to wall 30 of the lock case. The upper and lower edges of
the cover 20 are channeled at 42,42' to slide within tracks 43, 43'
at the outer edges of walls 31,31' , respectively. A flange 67 is
bent transversely from wall 32' to seat and conceal the free edge
of cover 20 in the closed position of the lock case when the screw
fasteners 66 interconnect the cover and the case at the inner wall
portion 41. The construction of the lock case and cover therefor
prevents the destruction thereof by crowbars or other prying
tools.
The slots 36 in the lock case are adapted to receive the lugs 53
which project from the face 51 of the strike S which is affixed to
the stile F of the door frame. The lugs 53 are fitted with aligned
apertures 55 so that when the lugs 53 enter the slots 36 in the
lock case, the openings 55 are in alignment with the line of travel
of bolts 35,35' when the door is in closed position. The door may
be locked by reciprocating the bolts adjacent to the bolts 36 so
that they engage the cylindrical apertures 55 in the lugs 53 to
effect a secure locking of the door within the frame. The turning
of the lock and the movement of the bolts from beyond the field of
slots 36 results in a movement of the bolts from the openings 55 in
the lugs 53 so that the door may be opened by knob K.
The mounting of the strike S is effected by means of screw
fasteners 56 of substantial lengths of approximately two and
one-half inches or longer so that the introduction of such
fasteners into the two transverse plates 51 and 52 of the strike,
results in the penetration of these fasteners not only into the
frame, as is conventionally done, but also into the structural
timbers T backing up the frame, so that a prying of the strike from
the frame with a crowbar or similar tool is rendered
impossible.
As may be seen from FIGS. 1 to 4, when the door is in closed
position and locked, the screw and bolt fasteners of the entire
assembly, namely, 14, 66 and 56, are invisible so that tampering
with such, to effect an illegal opening, is rendered
impossible.
In order to attain maximum security for the lock assembly, the
cover 20 for the lock case, on the internal side of the door, is
fabricated of tool-resistant metallic alloy material and is formed
with a frusto-conical protrusion 21 is substantial alignment with
the protrusion 11 on the outside of the door. A pin tumbler lock
65, similar to lock 15, containing a large number of pin tumbler
units 67, with rows of backup tumbler sets 67' and 67", is affixed
to the interior of the protrusion by bolting, soldering, brazing or
welding, and the inner end of the rotary plug 68 is connected with
an oscillating crank 69 which is operative in the same range of
movement as is the oscillating crank 19 controlled by the lock 15
to actuate the sliding plate 33 and the bolts 35,35' to effect the
engagement and disengagement of the bolts with the apertures 55 in
the lugs 53 of the strike S when the door is in closed
position.
The flattened exterior portion 22 is provided with a restricted
opening 63 which permits the insertion of the key into the keyhole
at the outer end of the lock 65 and the rotation thereof while
concealing the outer face of the lock and particularly the area
immediately beyond the shank of the key which effects a lifting of
the pin tumblers to release the plug for rotation whereat drilling
tools are introduced to effect the destruction of the lock
mechanism.
In this construction as well, a space is presented between the
outer face of the lock 65 and inner face of the plateau 22 of the
protrusion which renders difficult the introduction of lock picking
tools into the keyhole. This space may be filled by one or more
layers 71 of steel alloys which are especially resistant to
penetration by drilling or other destructive instruments.
This arrangement renders the disabling of the lock as difficult
from the inner side of the door as it is from the outer side of the
door, but the introduction of the proper key into the keyhole
effects a locking and an unlocking of the door by the second
oscillating crank 69 which controls the bolt actuating mechanism in
the same manner as does the first oscillating crank 19.
In FIG. 6 is shown the outer face of the armor plate 11 at the
flattened portion 12, on an enlarged scale. The outer face 15' is
visible through the opening 13 in the armor plate for the insertion
of the key into the slot 75.
In FIGS. 8 to 10 is illustrated a specially designed key for the
reliable operation of the safety lock 15 which is comprised of a
shank 80 ground specially along one of its edges 81 corresponding
to the arrangement of the pin tumbler units in the lock. The key is
recessed at the portion 83 between the handhold 82 and the shank
80, so that following the insertion of the key into the keyhole
slot with the edge 81 coincident with the end 76 of the keyhole
slot, the plug 17 may be rotated to effect the movement of the
tailpiece 18 and the oscillating crank 19 connected thereto. In
order to reenforce the key, propulsion pins 85 are provided on the
inner face of the handhold 82 which engage correspondingly-shaped
openings 86 in the outer face of the rotary core 17 to attain a
more secure engagement between the key and the plug in the course
of its rotary movement. The recessed portions 83 of the key permit
the rotation of the key and the plug while the area designated X in
dotted lines in FIG. 6 of the outer face 15' of the lock is
concealed by the armor plate surface 12. This area is the most
vulnerable part of the lock for the introduction of drilling tools,
which are capable of disabling the locking effects of the pin
tumbler units. The shielding of the outer face of the lock at this
vulnerable area supplements the safety afforded by the use of pins
of alloy steels within the lock, which are resistant to destruction
by drilling tools.
The security of the locking mechanism is further enhanced by
insuring against the destruction of the lock by damaging the
connections between the lock mechanism and the bolt actuating
mechanism, and particularly by destroying the effectiveness of the
tailpiece 18 extending between the rotary core or plug 17 and the
bolt actuating mechanism within the lock case C. Protection against
this damage is afforded by surrounding the cylindrical lock 15 with
a tool resistant metallic shield 90 which is affixed to the
interior of the protrusion 11. A similar protective cylinder 91, of
tool resistant material, is affixed to the inner face of attachment
plate 60 onto which is affixed the lock case C. These cylinders are
of slightly different diameter so that they may interfit
reciprocably for the purpose of accommodating doors of different
thicknesses. The provision of this protective shell around the lock
15 and the connections extending therefrom precludes an approach to
the lock and its connection from beyond the area of the armor plate
10 to effect its destruction.
The advantages of the invention may be realized in different
degrees depending upon the measure of security sought to be
attained and the character of the application of the lock assembly
to the specific door closure. In the embodiment of the invention
described above, a lock assembly is shown which requires the
operation of the lock by a key, both from the inside as well as the
outside of the door, so that even if a burglar should succeed in
entering the premises unlawfully by some other mode of ingress,
such as a window, a rapid point of exit would be denied him since
the lock assembly, even from inside the premises, would be
substantially tamper-proof. However, the advantages of the
invention may be realized to lesser degrees if the lock assembly is
operated from one side of the door to the exclusion of the other
side, or if other means, such as a hand knob is used for
controlling the lock on one side, as an adjunct to the operation of
the lock from the opposite side by a key. Such arrangements are
shown in the group of patents mentioned above, and in such
arrangements, a flat armor face plate could be used on one side of
the assembly with no keyhole therein.
Of course, if the alternate operation of the lock by a handknob is
not desired, a safety lock may be attained which is operable only
from the outside by providing a flat closure plate for the lock
assembly beyond the bolt actuating mechanism. Such would be useful
for inward opening doors as is the case with the arrangement
described above. Such an arrangement with a blank flat plate may be
used for operation by a key from the inside only when the lock
assembly is applied to back doors, where there is no need to admit
people by key from the outside.
It is understood that the lock assembly may be constructed in many
different sizes to adapt the same for use in residences as well as
for larger installations, in warehouses and other large
enclosures.
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