Curb box locking device

A curb box locking device has a core unit with a head at its upper end and a foot at its lower end. A sleeve surrounds and is shiftable axially in relation to the core unit. Claw members are carried on the core unit for pivotal movement through side openings in the sleeve. The locking device is externally configured and dimensioned to be lowered into the curb box to a position at which the foot of the core unit is at rest on a valve or the like at the bottom of the curb box. The sleeve is engageable with the claw members during upward displacement of the sleeve relative to the core unit to pivotally urge the claw members radially outwardly into extended positions engaging the interior of the curb box to thereby resist upward removal of the locking device. The locking device is upwardly removable from the curb box by employing a tool specially designed to pull upwardly on the core unit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to locking devices, and is concerned in 
particular with an improved lock for preventing unauthorized access to a 
utility valve or the like located at the bottom of a curb box. 
2. Description of the Prior Art 
As shown for example by U.S. Pat. No. 135,822 (Laforge); U.S. Pat. No. 
1,229,429 (Farley) and U.S. Pat. No. 5,234,029 (Thomas et al.), curb box 
locks are conventionally located at ground level. Locks of this type are 
easily accessible and thus prone to being picked, broken or otherwise 
compromised by those seeking unauthorized access to valves located at the 
bottom of the curb boxes. 
The objective of the present invention is to provide an improved lock which 
can be dropped into the curb box, and which is not readily removable from 
the curb box without employing a tool specially designed for that purpose. 
SUMMARY OF THE INVENTION 
The locking device of the present invention includes a core unit surrounded 
by an axially shiftable sleeve. The core unit has a specially configured 
tip protruding above the sleeve, and claw members pivotal through side 
openings in the sleeve. The locking device is externally configured and 
dimensioned to be dropped into the curb box to a position resting on the 
valve to be protected from unauthorized access. The locking device is 
removable vertically from the curb box by employing a tool specially 
designed to grip the specially configured protruding tip of the core unit. 
Any attempt to otherwise remove the locking device, as by pulling upwardly 
on the sleeve, will be prevented by the claw members being pivotally urged 
outwardly into engagement with the interior of the curb box. 
These and other features and advantages of the present invention will 
become more apparent as the description proceeds with reference to the 
accompanying drawings, wherein:

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
With reference initially to FIGS. 1-3A, a conventional tubular curb box 10 
is shown extending downwardly from ground level 12 to a valve 14 in a 
utility conduit 16 for the supply of gas, water, etc. A removable cap 17 
closes off the top of the curb box. The cap 17 is secured in place by a 
screw 18 threaded into an underlying radially protruding boss 19 on a 
collar at the top of the curb box 10. 
A locking device in accordance with one embodiment of the present invention 
is generally depicted at 20. As can best be seen in FIG. 3, the locking 
device includes a core unit having a body 22 connected to a foot 24 by an 
intermediate shaft 26. The body has an upper cone-shaped tip 28, and is 
slotted as at 30 to accommodate a pair of claw members 32 mounted for 
rotation on a cross pin 34. The tip 28 is circumscribed by a groove 36. As 
can be best seen in FIG. 3, each claw member 32 has a straight upper edge 
32a, a curved cam surface 32b and a jagged nose 32c. 
An outer sleeve 38 surrounds and is axially shiftable with respect to the 
core unit. The sleeve 38 is surrounded adjacent its upper end by a solid 
heavy duty collar 40. A second collar 42 is located at the lower end of 
the sleeve. The collars 40, 42 are dimensioned to fit closely within the 
interior surface 44 of the curb box 10, and to thus slidingly guide the 
locking device as it is dropped downwardly to a position at which its foot 
24 rests on the valve 14. Upper collar 40 is recessed as at 41 to allow 
the locking device to pass by the inwardly protruding boss 19 at the upper 
end of the lock box. 
The outer sleeve 38 has oppositely facing side openings 46 aligned with and 
through which the claw members 32 protrude. One edge of each side opening 
46 has a stepped configuration defining upper and lower ledges 46a, 46b. 
When the locking device is at rest on the valve 14, as shown in FIGS. 1-3, 
the sleeve 38 is at its lowermost position, with the ledges 46a of the 
side openings 46 acting on the upper edges 32a of the claw members 32 to 
bias the claw members into retracted positions, with the jagged noses 32c 
spaced inwardly from the interior surface 44 of the curb box 10. The upper 
collar 40 coacts with the interior surface 44 to isolate the valve 14 from 
unauthorized access from above. 
Removal of the locking device 20 may be accomplished with a specially 
designed tool of the type shown at 48 in FIG. 7. The tool has a long 
handle 50 with a head 52 at its lower end. As shown in FIGS. 8 and 9, the 
head 52 has an internal recess 54 configured to receive the cone-shaped 
tip 28 on the core unit of the locking device. A split ring 56 seated in 
an internal groove 58 in the recess 54 slides over the conical surface of 
the tip (as shown in FIG. 8) and ultimately snaps into the groove 36 (as 
shown in FIG. 9) to mechanically interlock the head 52 to the tip 28. 
Thereafter, the handle 50 can be pulled upwardly to extract the locking 
device from the curb box. Because the upward force is being exerted via 
the tip 28 on the core unit, with the sleeve 38 remaining in its lowered 
position with respect to the core unit, the upper ledges 46a of the 
openings 46 will continue to bear down on the upper edges 32a of the claw 
members 32, thereby retaining the claw members in their retracted 
positions spaced inwardly from the interior surface 44 of the curb box. 
In the event that an unauthorized attempt is made to remove the locking 
device, as for example by pulling the collar 40 upwardly with a pick 60 as 
shown in FIGS. 4 and 5, upward shifting of the collar with respect to the 
core unit will result in the upper ledges 46a of the side openings 46 
being elevated from the upper edges 32a of the claw members 32, leaving 
the claw members free to rotate outwardly about the cross pin 34 and 
resulting in their jagged noses 32c engaging the interior curb box surface 
44. Continued elevation of the collar 40 and its integral sleeve 38 
relative to the core unit will eventually bring the lower edges 46b of the 
openings 46 into contact with the cam surfaces 32b of the claw members 32, 
resulting in the jagged noses 32c being jammed against the interior curb 
box surface 44, thereby preventing further upward removal of the locking 
device. 
A second alternative embodiment of a locking device in accordance with the 
present invention is depicted at 62 in FIGS. 10 to 16. The locking device 
62 has a core unit again including a body 64 connected to a foot 66 by an 
intermediate shaft 68. The body is slotted as at 70 to accommodate a pair 
of claw members 72 mounted for rotation about a cross pin 74. Each claw 
member has an upper edge 72a, a curved cam surface 72b and a jagged nose 
72c. An outer sleeve 76 surrounds and is axially shiftable in relation to 
the body 64. As can best be seen in FIG. 11A, sleeve 76 is provided with 
side openings 78 formed with ledges 80. The claw members 72 protrude 
through the side openings 78, and as can best be seen in FIG. 11B, the 
ledges 80 underlie the cam surfaces 72b of the claw members 72. Upper and 
lower collars 82, 84 again surround and are integral with the sleeve 76. 
The collars 82, 84 coact in sliding contact with the interior curb box 
surface 44 to guide the locking device as it is dropped into the curb box, 
ultimately to come to rest with its foot 66 supported on the valve 14. 
The core unit further includes a head 86 axially shiftable in relation to 
both the body 64 and the surrounding sleeve 76. The head has an upwardly 
protruding conical tip 88 interrupted by dimples 90. A pin 92 extends 
downwardly from the head 86 through the upper end of body 64 to the slot 
70 for pivotal connection at 94 with a pair of links 96, each link in turn 
being pivotally connected at 98 to one of the claw members 72. 
A spring 100 interconnects lower ends of the claw members and serves to 
rotatably bias the claw members outwardly, thereby pressing their jagged 
noses 74c into contact with the interior curb box surface 44. 
Any attempt to vertically extract the locking device 62 from the curb box 
by pulling upwardly on the outer sleeve 76 via collar 82 will cause the 
ledges 80 to bear upwardly on the cam surfaces 72b of the claw members, 
thus adding to the biasing action of the spring 100 to further jam the 
jagged noses 72c into the interior curb box surface 44. 
In order to remove the locking device, and as shown in FIG. 12, the head 86 
is pulled upwardly in relation to both the body 64 and sleeve 76, thereby 
acting via pin 92 and links 96 to overcome the biasing action of spring 
100, causing the claw members to collapse inwardly and away from the 
interior curb box surface 44. The entire unit can then be pulled upwardly. 
Removal of the locking device is accomplished with the tool 102 depicted in 
FIGS. 13 to 16. The tool includes an outer tube 104 containing an inner 
sleeve 106, which in turn contains a rod 108. The lower end of rod 108 
tapers outwardly and has an end recess 110 shaped to receive the upwardly 
protruding tip 88 on the head 86 of the locking device. The wall of the 
recess 110 has apertures containing balls 112 urged inwardly into locked 
positions by the surrounding tapered inner surface of sleeve 106. 
The sleeve 106 and rod 108 are provided respectively with mutually spaced 
handles 114, 116 protruding outwardly through a slot 118 in the outer tube 
104. The tube 104 and sleeve 106 are further provided with mutually spaced 
brackets 120,122, with bracket 120 being pivotally connected at 124 to a 
lever 126, and with the lever 126 being pivotally connected at 128 to a 
link 130 which in turn is pivotally connected at 132 to bracket 122. A 
spring 134 is located between an enlarged diameter head 136 of the rod 108 
and an interior shelf 138 on sleeve 106. 
In the condition shown in FIG. 13, the tool is in a free state, with the 
balls 112 urged inwardly into locked positions. By urging the handles 114, 
116 together, as shown in FIG. 14, the spring 134 is compressed as the end 
of the rod 108 projects outwardly from the sleeve 106 to unlock the balls 
112. This allows the upwardly protruding tip 88 of the locking device 62 
to enter the recess 110, with the balls 112 being received in the dimples 
90. As shown in FIG. 15, the handles 114, 116 are then allowed to move 
apart under the influence of the expanding spring 134, causing the balls 
112 to be locked into the dimples 90. As shown in FIG. 16, lever 126 is 
then actuated to pull head 86 upwardly with respect to the upper sleeve 
collar 82, which as previously noted, causes the claw members 72 to 
collapse inwardly away from the interior curb box surface 44. The tool can 
then be pulled upwardly to extract the locking device 62 from the curb 
box. 
In light of the foregoing, it will be seen that both embodiments of the 
present invention provide locking devices that can be dropped into the 
curb box to safeguard the underlying valve from unauthorized access. Both 
embodiments are designed to thwart their extrication by any means other 
than a tool specially designed for that purpose. 
The position of the groove 36 in the tip 28 of the first embodiment can be 
shifted vertically, necessitating a corresponding change to the design of 
the tool head 52. A similar result can be achieved by shifting the 
elevations or changing the number of the dimples 90 in the tip 88 of the 
second embodiment. In this way, different locking devices can be supplied 
to different utilities, with each utility having its own tools designed to 
operate only its locking devices.