Lockable composite manhole cover system, apparatus and method

A lockable manhole cover system including a manhole cover and a locking mechanism attached to the bottom surface thereof and including a fixed end and an actuated end, each including locking pins movable between locked and unlocked positions. The actuated end includes a keyed lock. When in the locked position, the free ends of the locking pins extend beneath a flange prevent the cover from being lifted up. When the actuated side is moved to the unlocked position via the key, the locking pin free ends retract such that the cover is free to be lifted from the ring. On the fixed side, the locking pins are biased to move to their extended positions upon manual depression of a release stem located at the upper surface of the cover.

BACKGROUND OF THE INVENTION

The present invention relates to a lockable composite manhole cover system, apparatus and method which enables quick attachment and removal of the manhole cover while providing an integrated, secure locking system to prevent unauthorized access to the underlying structure.

SUMMARY OF THE INVENTION

In one embodiment, the invention comprises a lockable manhole cover system including a manhole cover removably attached to a cover mounting ring having an outer flange for securing the ring to a surrounding structure such as an underground vault or concrete column, for example. The cover when attached to the ring will lie substantially flush with the surrounding area such as a road. A locking mechanism is attached to the bottom surface of the cover and includes a fixed end and an actuated end, each including at least one but preferably two locking pins which are movable between locked and unlocked positions. When in the locked position, the free ends of the locking pins extend beneath an inner flange extending radially inwardly on the inside surface of the ring thereby preventing the cover from being lifted up and off the ring. When moved to the unlocked position, the locking pins free ends retract and locate radially inwardly of the flange such that the cover (and locking mechanism which is mounted thereto) is free to be lifted from the ring.

On the actuated side, a lock extends through a hole in the cover and is accessible on the top (exposed) surface of the cover. A key is used to engage the lock and move the locking pins on the actuated side to the unlocked position. Springs bias the locking pins into their extended locked position such that removal of the key from the lock biases the locking pins into their extended, locked positions on the actuated side. The key includes a threaded cylinder allowing it to be removably threaded to the lock which allows the user to lift and manually manipulate the cover using the key and a handle attached to and extending from the key.

On the fixed side, a release having a main body portion with a stem is provided and is configured to be moved between engaged and released positions relative to the locking pins on the fixed side. When the locking pins are in the retracted position, the release body is moved to engage the locking pins on the fixed side and the stem extends above the top upper surface of the cover and is manually accessible to be selectively pushed down into the released position. When in the released position, the main body portion of the release disengages the locking pins on the fixed side which are biased by springs to move into their extended, locked position.

Additional objects, advantages and novel aspects of the present invention will be set forth in part in the description which follows, and will in part become apparent to those in the practice of the invention, when considered with the attached figures.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawing, there is seen inFIGS. 1aand 1ban embodiment of the invention comprising a lockable manhole cover system10including a manhole cover12removably attached to a cover mounting ring14preferably made of a strong, durable metal such as cast iron, for example. Ring14includes a flange14ahaving bolt holes14bfor securing ring14to a surrounding/underlying structure such as an underground vault or concrete column, for example, with the relative positioning being such that cover12will lie substantially flush with the surrounding area such as a road, for example (not shown). Cover12is preferably made of a composite material such as a molded high quality fiber glass and resin with a molded urethane perimeter edge12a(which may be co-molded with the rest of cover12or formed separately and subsequently attached thereto), although other suitable materials are possible as may be desired.

Cover12includes an upper surface12band lower surface12c(see alsoFIGS. 2aand 2b). Ring14further includes an upper edge14fand a flange14dformed on and extending radially inwardly of inner wall14eof ring14(seeFIGS. 1a, 3band 11b) thereby forming a cover locating area between flange14dand said ring upper edge As seen inFIG. 3b, the distance D1between flange14dand ring upper edge14fis substantially the same as the thickness “T1” of cover12at circumferential edge12asuch that cover top surface12bsits substantially flush to ring upper edge14fwhen cover12is fully seated on flange14d.

Locking mechanism16is mounted to the lower surface12cof cover12with threaded bolts (not shown) which extend through cover12from upper surface12bto lower surface12c, with the threaded bolts threading through respective holes18a,18band into respective aligned holes20a′,20a″ formed in first front stanchion20a, and threading through respective holes18c,18dand into respective aligned holes20b′,20b″ formed in second front stanchion20b(see alsoFIGS. 3aand 11a).

Locking mechanism16further includes first and second back brackets22aand22b, and first and second side trusses24aand24bwhich extend in spaced, parallel relation to each other and between which the front stanchions and back brackets extend and attach.

Locking mechanism16is considered to have two opposite ends referred to herein as the fixed end19and the actuated end21. The actuated end21is referred to as such since it includes the keyed lock explained in detail below.

With reference to fixed end19, first and second longitudinally spaced holes30aand30bare formed in first front stanchion20aand these holes align with respective first and second longitudinally spaced holes34a,34bformed in first back bracket22a. First and second locking pins26aand26bmay freely and slidingly extend through respective aligned holes30a,34aand30b,34bin the first front stanchion20aand first back bracket22a. A first locking pin yoke40(FIGS. 6a, 6b) is provided having first and second longitudinally spaced holes40aand40bwhich align with respective aligned holes30a,34aand30b,34bin the first front stanchion and first back bracket. At least one but preferably two locking pins referenced herein as first and second locking pins26aand26bextend through respective holes40aand40bin a fixed, non-sliding manner via locking pin slots26a″ and26b″ engaging with respective, aligned flanges40a′ and40b′ located on the inwardly facing surfaces of holes40aand40b, respectively. As such, locking pins26a,26bmove together with first locking pin yoke40for reasons explained in detail below. It is of course understood that other means of fixing locking pins26aand26bto first locking pin yoke20amay be utilized as desired. First and second locking pins26aand26beach include a respective spring “S” mounted thereon between the first back bracket22aand first locking pin yoke40. It is noted that first locking yoke40is not shown inFIGS. 4 and 8so as to reveal and describe other components which would be otherwise obscured by the first locking yoke in these figures.

With reference now to actuated end21, first and second longitudinally spaced holes32aand32bare formed in second front stanchion20band these holes align with respective first and second longitudinally spaced holes36a,36bformed in second back bracket22b(seeFIGS. 7, 9, 14 and 15). At least one but preferably two locking pins referred to herein as third and fourth locking pins26cand26dmay freely and slidingly extend through respective aligned holes32a,36aand32b,36bin the second front stanchion20band second back bracket22b. A second locking pin yoke42(see alsoFIGS. 16aand 16b) is provided having first and second longitudinally spaced holes42aand42bwhich align with respective aligned holes32a,36aand32b,36bin the second front stanchion and second back bracket. Third and fourth locking pins26cand26dextend through respective holes42aand42bin a fixed, non-sliding manner via locking yoke flanges42a′ and42b′ engaging respective locking pin slots (not shown) on locking pins26cand26din the same manner as described above regarding locking pins26aand26bengaging first locking yoke40. As such, third and fourth locking pins26c,26dmove together with second locking pin yoke42for reasons explained in detail below. Third and fourth locking pins26cand26deach include a respective spring “S” mounted thereon between the second back bracket22band second locking pin yoke42.

Referring now to the keyed lock located at actuated end21, second locking pin yoke42is seen to include a center post42c. An actuating link44is provided and includes a base portion44aand arm portion44bextending from the base portion44a. In one embodiment, an elongated slot44b′ extends through arm portion44bfrom top surface45to bottom surface47thereof, and a counter sunk hole44a′ is formed into the top surface45of base portion44a.

An actuating bolt46having a shank portion46aand a head portion46bis mounted to actuating link44via an insert48which fits within countersunk hole44a′ of the actuating link44. Insert48includes a neck portion48aand an annular head portion48bwith an insert shoulder48dlocated radially inwardly of head portion48b. A center through bore48cis defined at the center of shoulder portion48dand extends through the entire length of neck portion48a. The shank portion46aof actuating bolt46extends through center through bore48cuntil actuating bolt head portion46bis located on insert shoulder48d. Actuating bolt shank portion46ais longer than insert neck portion48asuch that the shank portion free end46a′ extends beyond insert neck portion48a. A laterally extending though hole46cis formed in actuating bolt46adjacent free end46a′ thereof. This through hole46caligns with actuating link through hole44cwhereby a pin (not shown) may be extended through aligned holes46cand44cto rotationally fix actuating bolt46to actuating link base portion44a.

When locking mechanism16is mounted to cover12as explained above, the insert head portion48bextends through cover hole12esuch that the insert head portion48band actuating bolt head portion46bare exposed at cover top surface12bwith insert top surface48′ lying substantially flush with cover top surface12b(seeFIG. 20). Actuating bolt head portion46bis exposed at cover top surface12band is coaxially positioned and spaced radially inwardly relative to insert head portion48bsuch that an annular space50is formed therebetween. Actuating bolt head portion46bincludes an outer ring portion46dhaving a threaded external surface46d′ (see alsoFIG. 18). A counter sunk surface46eis located radially inwardly of outer ring portion46dand a key registration boss46fis located at the center of counter sunk surface46esuch that an annular space46gis formed therebetween. The radially inwardly facing wall of outer ring portion46dis formed as a non-rounded (e.g., polygonal) surface46hso as to be able to removably engage the key60in a rotationally fixed manner as described below.

As seen inFIGS. 21aand 21b, a key60is provided having an outer cylinder portion60ahaving internal threads60a′. The outer cylinder portion60ais freely rotatable with respect to a center lock head62having a center dimple62aand external, non-round (e.g., polygonal) surface62b. Key60may be used to turn actuating bolt46to lock and unlock cover12from ring14. More particularly, key outer cylinder portion60ais inserted into the space50between insert head portion48band actuating bolt head46bwhile also locating dimple62aonto registration boss46fThe inwardly facing, non-round surface46hof the actuating bolt head46bis complimentary shaped to the outwardly facing, non-round surface62bof key center lock head62. As such, these two surfaces may removably engage one another in a rotationally fixed manner. To attach key60to actuating bolt46, cylinder portion60ais turned such that the inner threaded surface60a′ of cylinder portion60athreads to the outer threaded surface46d′ of actuating bolt outer ring portion46dand thereby removably securing these two parts together. In other words, key60cannot be detached from actuating bolt46until cylinder portion60ais manually rotated in the opposite direction to disengage these threaded surfaces from each other. This allows the user to use the key handle64to lift the manhole cover12from the ring14and carry and move the cover12about when the locking mechanism16is in the unlocked condition as will be described in more detail below.

Actuating link44is connected to second locking pin yoke42by inserting center post42cthrough elongated slot44b′. Rotation of actuating link44using key60causes center post42cto slide within elongated slot44b′ in the manner of a cam. More particularly, the rotational movement of the actuating link44causes pivoting of actuating link arm portion44bwhich is translated into linear movement of the second locking pin yoke42together with respective third and fourth locking pins26c,26dwhich, as explained above, are fixed to second locking pin yoke42but freely slide within their respective and aligned holes32a,36aand32b,36bformed in the second front stanchion20band second back bracket22b. It is noted that slot44b′ is one of many possible configurations for creating a cam between actuating link44and second pin locking yoke42. For example, slot44b′ may be eliminated and actuating link44may simply press directly against a portion of second locking pin yoke42such as post42c.

When actuating link44is rotated in the clockwise direction, the second locking pin yoke42(and hence also third and fourth locking pins26cand26d) is moved toward second back bracket22bwhich thereby compresses springs “S” located therebetween (seeFIG. 15). When springs “S” are compressed, second locking pin yoke42is biased in the direction toward second front stanchion20b. The movement of second locking pin yoke42toward second back bracket22bretracts third and fourth locking pins26cand26dwhich removes their respective free ends26c′ and26d′ from beneath ring flange14dand thereby allows cover12to be lifted from ring14using key60as described above. This is the unlocked condition of actuated end21of locking mechanism16.

Turning attention now again to fixed end19, as described above, first and second locking pins26aand26bare fixed to first locking pin yoke40and extend through and freely slide within aligned holes formed in first front stanchion20aand first back bracket22a. Springs “S” are mounted on first and second locking pins26a,26bbetween first back bracket22aand first locking pin yoke40. As seen best inFIGS. 14band 14c, a fixed side release70is provided having a main body portion72and stem portion74extending from the body portion. Body portion72includes opposite side edges72aand72bwhich are sized to removably and slidingly engage the facing slots26a″′ and26b′″ (seeFIG. 4) on the first and second locking pins26aand26b, respectively. Stem portion74telescopes through and freely slides within an insert76which remains stationary and is mounted within hole12f(FIGS. 2a, 2b) formed through cover12. Fixed side release70may be manually manipulated between a raised position and a depressed position relative to stationary insert76and cover12(it is noted that the term “manually” is to be broadly interpreted to include any means of applying a force without a tool). When moved to the raised position, the opposite side edges72aand72bslide into facing slots26a′″ and26b″′ thereby holding the locking pins in their retracted (unlocked) positions.

Once cover12has been initially mounted onto ring14, the exposed free end74aof stem portion74is raised above cover top surface12bas seen inFIGS. 1aand13. When ready to lock cover12to ring14, the user manually pushes the stem portion74adown against cover12which moves the release body side edges72aand72bout of locking pin slots26a″′ and26b′″. The locking pins are then biased by the locking pin springs “S” into their extended, locked positions whereby locking pin ends26a′ and26′ locate beneath ring inner flange14das seen inFIGS. 3aand 3b. In this position, the stem free end74ais substantially flush with insert76and cover top surface12b(seeFIGS. 1band10). As such, the stem is not accessible (either manually or with a tool) to be moved into a raised position until cover12is removed from ring14using the actuated side lock.

A worker (or other person) may alternately mount and remove lockable manhole cover system10to and from cover mounting ring14as follows:

Beginning from a mounted and locked position as seen inFIGS. 1b, 3aand 3b, the worker removes the protective cap (not shown) from actuating bolt head46band engage key60by inserting cylinder60ainto space50with key dimple62amounted over registration boss46fand turning cylinder60clockwise until cylinder internal threaded surface60a′ threads to threaded surface46d′ of the actuating lock head46b. This secures key60to the actuating bolt46. Using handle64, lock head62is rotated clockwise about 45° which in turn rotates actuating bolt46while cylinder60aremains stationary. The clockwise rotation of actuating bolt46causes actuating link44to move second locking yoke42, and thus also locking pins26cand26d, toward second backing bracket22b. This movement retracts the locking pins26cand26dto the unlocked position where the locking pin free ends26c′ and26d′ are clear of ring flange14d(seeFIGS. 11a, 11band 14a). The worker may put slight pressure on the key in a direction away from their body while turning the key which will cause the cover to tilt relative to ring14.

Once tilted a couple of inches with the locking pin free ends cleared and raised above flange14, while the cover is kept in this tilted position (by the worker keeping forward pressure on the key60), the key is rotated in the opposite direction to its original position which extends the locking pins back toward their extended position. Since the locking pin free ends are above flange14at this point, this allows the worker to release the forward pressure on the key which moves the cover back toward the untilted position and the pin free ends on the actuated side21may then be seated on the top of flange14. The worker may then use handle64to lift the cover12from the ring14.

It will be appreciated that the locking pins26aand26bremain in their extended positions throughout the foregoing maneuvers, however, as the worker lifts the actuated side21from ring14, the cover12is set at an angle relative thereto and the fixed side locking pin free ends26a′,26b′ may then be easily withdrawn from beneath ring flange14f.

The worker may use handle64to lift and place the cover12upon its side on the ground with the handle64placed on the ground and cover attached to key60due to cylinder60remaining threadedly engaged to actuating bolt46.

Removal of cover12from ring14as described above provides access to the underlying structure for any reason (e.g., to inspect an underground sewer line, to run underground cable, etc.). When ready to re-mount the cover12to the ring14, the worker may first resets fixed side19to the unlocked (locking pins retracted) position by manually sliding first locking pin yoke40toward first backing bracket22awhich retracts first and second locking pins26a,26bwhile also compressing their respective springs “S”. Once the locking pins26a,26bare moved to the point where their respective locking pin slots26a′″ and26b′″ are aligned with release70, the release70is manually pushed at bottom edge72c(see alsoFIGS. 14b, 14c) until the release body side edges72aand72bslide into and engage locking pin slots26a″′ and26b″′, respectively. In this position, the release stem74araises and extends above cover upper surface12b(seeFIGS. 11band13). The first locking pin yoke40may then be manually released and the locking pin yoke40and the locking pins26a,26bwill stay in their retracted position against the bias of their respective springs “S” due to the engagement of the release side edges72a,72bin locking pin slots26a″′,26b′″. The cover12is now ready to be (re)mounted to ring14.

With key60still attached to actuating bolt46as described above, the worker uses handle64to drag cover12back to the ring14and seats the fixed side19onto flange14dwith fixed side locking pins26aand26bstill in their retracted (unlocked) positions. Since these first and second locking pins26aand26bare retracted, their respective free ends26a′,26b′ clear the flange14dand locate below but radially inwardly of the flange14das seen at fixed side19inFIGS. 11aand11b.

On the actuated side21, since at this point in the cover (re)mounting process the actuated side locking pins26c,26dare still in their extended positions, the free ends26c′,26d′ thereof seat and rest upon the upper surface14d′ of flange14d. The worker may then turn key60clockwise to move the locking pins26c,26dtoward their retracted positions and, once clear of flange14d, the actuated side21of cover12falls by gravity until cover edge12afully seats upon flange14d. The worker then removes key60from actuating bolt46by unthreading cylinder60afrom actuating bolt head portion46band lifting key60away from cover12.

At the actuated side21, the springs “S” when compressed bias the second locking yoke42toward the second stanchion20bwhich thereby also biases the third and fourth locking pins26c,26dinto their extended positions. In this position, the locking pin free ends26c′ and26d′ extend beneath flange14das seen at actuated side21inFIGS. 3aand 3b. With the cover12thus fully seated on ring flange14d, the worker may then push down (e.g., by stepping upon) the release free end74awhich withdraws release body side edges72aand72bfrom the first and second locking pin slots16a″′,26b″′.

Once release70is disengaged from locking pins26a,26b, the bias of springs “S” on fixed side19cause first locking yoke40and thus also locking pins26a,26bto move toward first stanchion20auntil locking pin free ends26a′,26b′ become located beneath flange14d. A removable protective cap (not shown) may be installed over the actuating bolt head46bby pressing the cap into the space50. It will thus be appreciated that with now each of the first, second, third and fourth locking pin free ends26a′,26b′,26c′ and26d′ located beneath flange14d, cover12is effectively locked to ring14as seen inFIGS. 3aand 3band cannot be removed therefrom without the use of key60in the manner described above.