Front removable lock

A front removable lock for office furniture units, and the like, comprises a housing having an rear plug rotatably mounted in a rear portion of the housing. A front plug, having key operated tumblers, is telescopingly received within a front portion of the housing, and includes a latch mechanism which detachably connects the same with the rear plug. A release is mounted on the rear plug to uncouple the front and rear plugs, and is accessible through a window in the housing when the plugs are rotated into a partially unlocked position. A gate is mounted on the rear plug adjacent to the release, and is positioned such that the gate closes the window when the plugs are rotated into a locked position to prevent unauthorized access to the lock.

CROSS-REFERENCE TO RELATED APPLICATIONS 
The present application is related to my copending U.S. patent applications 
Ser. No. 362,454, filed Mar. 26, 1983, now U.S. Pat. No. 4,457,569, 
entitled LOCK ARRANGEMENT FOR OFFICE FURNITURE UNITS; and Ser. No. 
362,452, filed Mar. 26, 1983 now U.S. Pat. No. 4,445,729, entitled 
OVER-CENTERED LOCK ARRANGEMENT FOR OFFICE FURNITURE UNITS, which are 
hereby incorporated by reference. 
BACKGROUND OF THE INVENTION 
The present invention relates to office furniture units, and in particular 
to a front removable lock therefore. 
Lock arrangements for office furniture units, such as desks, credenzas, 
file cabinets, storage cabinets, and the like, are generally well known in 
the art. Front removable locks, such as those disclosed in publications by 
Chicago Lock Co., National Lock Hardware, Engineered Security Products, 
and Best, as noted in the Disclosure Statement, include a mechanism to 
remove and replace the tumbler assembly when required for repair, or to 
rekey the lock. 
Heretofore, front removable locks have required a special key or a special 
tool to remove the tumbler assembly, which can be somewhat inconvenient to 
use. Such locks have a rather complex construction which is expensive to 
manufacture, and typically difficult to maintain and/or repair. Prior 
front removable locks have required a rather wide housing, such that the 
mating clearance hole in the front of the furniture unit must be rather 
large, in the nature of 3/4 of an inch or greater. As a result, such locks 
are not particularly adapted for use in conjunction with compact, in-top 
lock arrangements, wherein the lock is concealed within the interior of 
the top of the furniture unit. 
SUMMARY OF THE INVENTION 
One aspect of the present invention is a front removable lock for office 
furniture units and the like, comprising a housing adapted for mounting in 
the furniture unit, and including a sidewall with an aperture therethrough 
positioned at a preselected location to define a window through which the 
lock is selectively accessed by a tool. A rear plug is rotatably mounted 
in a rearward portion of the housing, and includes means for axially 
positioning the rear plug in the housing. A front plug is telescopingly 
received in a forward portion of the housing, and is shaped for rotation 
therein between locked and unlocked positions. The front plug carries 
means such as tumblers, or the like for rotatably innerlocking the front 
plug and the housing in the locked position. A mechanism detachably 
interconnects the front and rear plugs, and includes a release to uncouple 
the plugs, and permit selective withdrawal of the front plug from the 
housing. The release is mounted on one of the plugs for rotation 
therewith, and is positioned to rotate into alignment with the housing 
aperture in a preselected, unlocked position, whereby insertion of the 
tool through the window and into engagement with the release uncouples the 
front and rear plugs. An imperforate gate is positioned adjacent to the 
release, and closes the window when the plugs are rotated to the locked 
position, thereby preventing tampering, surreptitious entry, or other 
unauthorized access to the lock. 
The principal objects of the present invention are to provide a front 
removable lock, having an uncomplicated construction which is less 
expensive to manufacture, and does not require any special keys or tools. 
The lock has a very compact design that is particularly adapted for in-top 
installations. A window in the lock housing provides ready access to the 
lock release, and is closed when the lock is rotated to the locked 
position to provide excellent security. The release mechanism can be 
easily manipulated by any type of slender bar or rod, including a bent 
paperclip, such that even unskilled personnel can easily remove and 
replace the front plug portion of the lock when required for repair and/or 
rekeying. A unique alignment mechanism assures that the front plug is 
inserted into the housing in the proper orientation. The lock is efficient 
in use, economical to manufacture, capable of a long operating life, and 
particularly well adapted for the proposed use.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
For purposes of description herein, the terms "upper," "lower," "right," 
"left," "rear," "front," "vertical," "horizontal" and derivatives thereof, 
shall relate to the invention as oriented in FIGS. 2-6. However, it is to 
be understood that the invention may assume various alternative 
orientations, except where expressly specified to the contrary. 
The reference numeral 1 (FIGS. 1 and 2) generally designates a front 
removable lock embodying the present invention, shown installed in an 
office furniture unit 2. Front removable lock 1 comprises a barrel or 
housing 3 (FIG. 7), with a rear plug 4 rotatably mounted therein. A front 
plug 5, having key operated tumblers 6, is telescopingly received within a 
front portion of housing 3, and includes a latch mechanism 7 which 
detachably connects the same with rear plug 4. A releasable catch 8 is 
mounted on rear plug 4 to uncouple the front and rear plugs 4 and 5, and 
is accessible through a window 9 (FIGS. 3 and 5) in housing 3 when plugs 4 
and 5 are rotated toward the unlocked position. When plugs 4 and 5 are 
rotated to the locked position, a gate 10 closes window 9 to prevent 
unauthorized access to the lock. 
Front removable lock 1 may be used in a wide variety of different types of 
office furniture units, including desks, credenzas, file cabinets, storage 
cabinets, and the like. The compact construction of lock 1 makes it 
particularly adapted for use in conjunction with in-top installations, 
such as the desk shown in FIGS. 1-6. 
In the illustrated example, desk 2 (FIGS. 1 and 2) includes an elongate top 
15, which extends the length of the unit, and is supported by a pair of 
end panels 16. A rear panel 17 interconnects end panels 16, and a pair of 
pedestals 18 are suspended from the lower side of top 15 on the left and 
right-hand sides thereof, and include compartment lock mechanisms (not 
shown) operably connected with lock 1 to lock and unlock compartments 19. 
Desk top 15 is described in detail in my copending United States patent 
applications entitled LOCK ARRANGEMENT FOR OFFICE FURNITURE UNITS and 
OVER-CENTERED LOCK ARRANGEMENT FOR OFFICE FURNITURE UNITS, which are 
referenced hereinabove, and comprises a formed, rigid shell 23 (FIGS. 3-6) 
which is bent rearwardly along one edge to define the forward edge 24 of 
top 15. A cover layer 25 overlies shell 23, and is attached thereto by 
means such as adhesive or the like, to provide an aesthetically pleasing 
appearance, as well as a writing surface. A U-shaped reinforcing channel 
26 is mounted within top 15 along the forward edge thereof, and comprises 
a base 27, upstanding sidewalls 28, and end flanges 29, which are oriented 
rearwardly, and fixedly attached to the lower surface of shell 23. Lock 1 
is inserted through mating, aligned apertures in channel sidewalls 28, and 
the forward edge 24 of top 15, and is detachably mounted therein by 
fasteners 30. A removable cover 31 encloses the lower, rearward portion of 
top 15. A trim strip 32 is attached to channel base 27 by fasteners 33, 
and extends over the free edge of cover 25. 
Trim strip 32 and channel base 27 have centrally located, aligned apertures 
38 and 39 respectively therethrough, which are disposed directly below the 
window 9 in lock housing 3, and permit insertion of a tool or pointed 
instrument 40 therethrough to engage releasable catch 8, as described in 
greater detail hereinafter. 
Housing 3 is a generally cylindrically-shaped structure, having a flange 44 
at the rearward end thereof, through which fasteners 30 extend to mount 
lock 1 within desk top 15. A rim 45 is positioned adjacent the forward end 
of housing 3, and centers housing 3 within channel 26. A slot 46 extends 
through the sidewall 47 of housing 3, and is adapted to receive a 
crescent-shaped key 48 therein for rotatably mounting rear plug 4, as 
described below. 
Window 9 also extends through housing sidewall 47, and has a generally 
rectangular plan shape. When lock 1 is installed in furniture unit 2, 
window 9 is oriented in a generally downwardly direction to align with the 
apertures 38 and 39 in the lower surface of top 15. The lower edge 49 of 
window 9 is inclined downwardly, along a substantially vertical plane, to 
facilitate insertion of tool 40. 
The longitudinally interconnecting locking action of latch 7 and releasable 
catch 8, as described below, has a very low profile, such that the width 
or outside diameter of housing 3 can be reduced substantially. In the 
illustrated example, the clearance aperture required for lock 1 is in the 
nature of 17/32 inches, as compared to prior front removable locks, which 
require 3/4 inch and more. Hence, lock 1 is particularly adapted for 
in-top applications, as illustrated herein. 
The interior of housing 3 (FIG. 7) includes four ribs or splines 52 which 
project radially inwardly from the interior surface of housing 3, extend 
longitudinally therealong, and are spaced 90.degree. apart. Splines 52 
define arcuate grooves 53 therebetween in which the tumblers 6 of front 
plug 5 are received rotatably to lock the assembly. A cylindrical collar 
54 is positioned at the forward end of housing 3, and includes a radially 
inwardly projecting tab or key 55 (FIGS. 13-15). The rearward end of 
housing 3 has a cylindrical sleeve bearing 56. 
Rear plug 4 (FIG. 7) is a generally cylindrically-shaped structure, sized 
for telescoping reception within housing 3, and includes a rearwardly 
extending shaft 59 with generally square end 60 to attach a link 
arrangement (not shown) thereto for manipulating the compartment lock 
mechanism. A cylindrically-shaped journal portion 61 of rear plug 4 is 
closely received within the mating bearing sleeve 56 of housing 3 to align 
rear plug 4 in a coaxial relationship within housing 3. The medial portion 
of rear plug 4 includes a circumferential groove 62, in which key 48 is 
received to positively, axially position rear plug 4 within housing 3. The 
forward end 64 of rear plug 4 includes a slot 65 therethrough, which opens 
to the exterior surface 66 of forward end 64 along one side thereof, and 
is closed at the opposite side. Slot 65 has a generally rectangular 
transverse cross-sectional shape, with an enlarged forward end or socket 
67. A pair of ribs 68 are positioned along the open side of slot 65 for 
purposes to be described in greater detail hereinafter. The closed surface 
66 of the forward end 64 of rear plug 4 defines gate 10, and includes a 
radially extending slot 69 in which releasable catch 8 is slidably 
received. Latch slot 69 has a rectangular transverse cross-sectional 
shape, and closely receives mating releasable catch 7 therein for 
reciprocal movement in a plane disposed generally perpendicular to the 
axis of rotation of plugs 4 and 5. 
As best illustrated in FIGS. 8 and 9, catch 8 includes a central aperture 
74 therethrough, defined by a generally rectangular plate or frame, having 
end segments 75 and 76, and side segments 77 and 78. The forward or 
leading edge 79 of inward frame end 76 is tapered downwardly to facilitate 
latching. The remaining edges of aperture 74 are also beveled to insure 
smooth coupling action. The lefthand side segment 77 (as viewed in FIG. 8) 
includes a laterally extending arm 80, which engages a spring 81 to 
resiliently bias catch 8 in a radially outwardly direction. A bolt or 
plunger 82 protrudes from the outer end segment 76, and has a generally 
rectangular transverse cross-sectional shape which is sized to be received 
within window 9 for purposes to be described in greater detail 
hereinafter. 
With reference to FIG. 7, tumblers 6 are mounted in front plug 5, and 
comprise spring loaded, disc-type tumblers which reciprocate transverse to 
the axis of rotation of front plug 5. Tumblers 6 are normally biased 
radially outwardly into the grooves 53 defined between housing splines 52, 
as shown in FIG. 13, to rotatably lock front plug 4 in housing 3. The 
forward end of front plug 5 is generally cylindrical in shape for pivotal 
reception within the collar 54 of housing 3, and includes an end slot 87 
(FIGS. 13-15) in which a key 88 is received. Insertion of key 88 retracts 
tumblers 6 into the body of front plug 5, as shown in FIG. 14, to permit 
rotation of front plug 5 with respect to housing 3. A keyway 89 extends 
longitudinally along one side of front plug 5, and mates with key 55 to 
insure that front plug 5 is properly aligned with rear plug 4 when the 
latter is inserted into housing 3. A circumferentially extending slot 90 
is disposed at the forward end of keyway 89, and permits front plug 5 to 
rotate 90.degree. between the locked and unlocked positions. Key 55 abuts 
the ends of slots 90 to form positive stops at the locked and unlocked 
positions. 
A hook-shaped latch arm 93 projects rearwardly from the rear end of front 
plug 5, and includes a generally rectangular shank 94 and a wedge-shaped 
stop or barb 95 at the free end thereof. Latch arm 93 also includes an 
enlarged key or plug 96, which has a rectangular transverse 
cross-sectional shape, and is closely received within the mating socket 67 
of rear plug 4 to positively transmit rotation therebetween when the front 
and rear plugs are coupled. 
Rear plug 4 is mounted in housing 3 by depressing catch 8, aligning rear 
plug 4 with housing 3, so that the plunger portion 82 of catch 8 is in 
line with window 9, and inserting rear plug 4 into the rearward end of 
housing 3 until groove 62 is aligned with key slot 46. Spring 81 will 
extend catch plunger 82 through window 9 when rear plug 4 is in its proper 
position. Contact between the upper segment 75 of catch 8 and the housing 
edges forming window 9 limits extension of catch plunger 82. Window 9 is 
preferably positioned through one of the splines 52 on the interior of 
housing 3, so that abutment between the spline and the catch plunger 82 
retains catch 8 in a retracted position during insertion of rear plug 4 
into housing 3. Crescent-shaped key 48 is inserted into mating housing 
slot 46, such that the free edge of key 48 rides in groove 62. Key 48 is 
then fixedly anchored in housing 3 by means such as staking or the like. 
Front plug 5 is inserted into housing 3 in the following manner. Key 88 is 
first inserted into the end slot 87 in front plug 5 to retract tumblers 6. 
Front plug 5 is then oriented so that keyway 89 is aligned with housing 
key 55. In the illustrated example, keyway 89 is aligned with key 55 when 
tumbler key 88 is inclined to the left at a 45.degree. angle, as viewed 
from the front of the lock. Front plug 5 is then inserted into housing 3, 
intil the leading edge of barb 95 abuts the inclined edge 79 of the inward 
segment 76 of catch 7. As rearward translation of front plug 5 continues, 
abutment between barb 95 and catch edge 79 retracts catch 7 inwardly 
against the force of spring 81, until barb 95 passes over the rearward 
face of catch segment 76, at which time spring 81 extends catch 7 radially 
outwardly, thereby capturing latch arm 93 therein, as shown in FIG. 12. 
The coupling of latch arm 93 in catch 7 prevents longitudinal or axial 
separation of front and rear plugs 5 and 4. The reception of the key 
portion 96 of front plug 5 into the mating socket 67 of rear plug 4 
rotatably interconnects the front and rear plugs. When rear and front 
plugs 4 and 5 are so coupled, the upper surface of plunger 82 is disposed 
slightly below the exterior surface 66 of rear plug 4, as shown in FIG. 
11, to permit plugs 4 and 5 to pivot together 90.degree. within housing 3. 
When key 88 is rotated to the vertical, locked position shown in FIGS. 5 
and 6, the imperforate portion of the exterior surface 66 of rear plug 4, 
which defines gate 10, closes window 9 to prevent unauthorized access to 
the lock. When key 88 is withdrawn from lock 1, plugs 4 and 5 cannot be 
rotated. 
To remove front plug 5 for repair or rekeying, the user first inserts key 
88 into front plug 5, and rotates plugs 4 and 5 to a preselected, unlocked 
position so that plunger 82 is aligned with window 9. Preferably, the 
removal position for front plug 5 is selected so that when plunger 82 is 
aligned with window 9, tumblers 6 are aligned with an adjacent housing 
spline 52. In this configuration, engagement between tumblers 6 and 
housing spline 52 prevents the withdrawal of key 88 from front plug 5. 
Hence, the enlarged, rounded end of key 88 can be easily grasped to 
facilitate withdrawing front plug 5 from housing 3 after the front and 
rear plugs 4 and 5 have been uncoupled. 
The user then inserts any type of reasonably slender, rigid bar or rod 40 
through the apertures 38 and 39 in the bottom of top 15, and into window 
9, as illustrated in FIG. 2. It is to be understood that rod 40 is not any 
special type of tool, and may comprise any handy or convenient instrument, 
such as the bent paperclip illustrated in FIG. 2. Hence, the inconvenience 
of locating special keys or tools to rekey the lock is eliminated. The 
user pushes the end of instrument 40 into abutment with the exterior 
surface of plunger 82, and forces the plunger inwardly against the force 
of spring 81, so that catch 8 disengages the barbed end 95 of latch arm 
93. With plunger 82 depressed, the user simply grasps the rounded end of 
key 88, and pulls front plug 5 forwardly out from housing 3. Instrument 40 
is then withdrawn from window 9, and spring 81 automatically extends 
plunger 82 through window 9, thereby positively positioning rear plug 4 in 
its proper orientation to receive the latch 93 of replacement front plug 
5, as shown in FIG. 12A. Hence, when the replacement front plug 5 is 
inserted into housing 3, latch 93 will align with the mating slot 65 in 
rear plug 4. 
Front removable lock 1 has a very uncomplicated construction, which is less 
expensive to manufacture, and enables even unskilled personnel to easily 
remove and replace the front plug 5 without any special tools. The release 
plunger and mating window concept not only facilitates quick and easy 
removal of front plug 5, but also maintains excellent security to prevent 
tampering or surreptitious entry by unauthorized personnel. Further, 
proper alignment is always maintained between the rear and front plugs 4 
and 5. The compact configuration of lock arrangement 1 particularly adapts 
the same for in-top installations. 
In the foregoing description, it will be readily appreciated by those 
skilled in the art that modifications may be made to the invention without 
departing from the concepts disclosed herein. Such modifications are to be 
considered as included in the following claims, unless these claims by 
their language expressly state otherwise.