Manhole cover locks, lockable manhole covers, and methods for locking a manhole cover

A locking assembly attachable to a manhole cover includes an arm disposable in a lowered position with the arm disposed in a first orientation engageable with a manhole frame supporting the manhole cover to inhibit removal of the manhole cover from a manhole frame, and disposable in a raised position and in a second orientation operable to allow removal of the manhole cover from the manhole frame. In an embodiment, the locking assembly may include the arm attached to a movable member having a spiral, helix, or curved groove and in which the movable arm is receivable in a bushing and a pin receivable in the groove.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to manhole covers, and more particularly to manhole cover locks, lockable manhole covers, and methods for locking a manhole cover.

BACKGROUND

Manhole covers made of cast iron make up the bulk of access covers in urban streets around the world. These covers have a proven record of durability, strength, and functionality. The high density of iron results in a cover of substantial weight preventing cover displacement during flooding conditions and minimizing the occurrence of theft.

Recently, gas or steam explosions below streets can cause manhole covers to become dangerous projectiles. For example, a cast iron manhole cover can weigh between 85 pounds and 300 pounds, and explosions can propel the cover from 1 foot to 50 feet into the air. Often during various events, particularly in large cities, utilities will temporary weld manhole covers to their manhole frames to prevent access in and out of the manhole.

SUMMARY

Shortcomings of the prior art are overcome and additional advantages are provided through the provision, in one embodiment, of a locking assembly for a manhole cover. The locking assembly includes, for example, a movable member having an upper portion and a lower portion, the upper portion supportable in an opening in a manhole cover adjacent to a peripheral edge of the manhole cover, an arm extending outwardly from the lower portion of the movable member and disposable below a bottom surface of the manhole cover. The movable member and the arm are disposable in a lowered position relative to the manhole cover with the arm engageable with a portion of a manhole frame below the manhole cover to inhibit removal of the manhole cover from the manhole frame. The movable member and the arm are disposable in a raised position relative to the manhole cover with the arm so that the manhole cover is removable from the manhole frame.

In another embodiment, a locking assembly for a manhole cover is provided. The locking assembly includes, for example, means, attachable to a manhole cover, for simultaneously moving and rotating an arm from a lowered position with the arm disposed at a first distance and at a first orientation relative to a bottom surface of the manhole cover so that the arm is engageable with a portion of a manhole frame to inhibit removal of the manhole cover from the manhole frame to a raised position with the arm disposed at a second distance less than the first distance and at a second orientation different from the first orientation relative to a bottom surface of the manhole cover so that the manhole cover is removable from the manhole frame.

In another embodiment, a locking assembly for a manhole cover is provided. The locking assembly includes, for example, a bushing attachable through an opening in the manhole cover adjacent to a peripheral edge, the bushing have a passageway therein, a pin inwardly extending into the passageway in the bushing, a movable member receivable in the bushing, the movable member having a groove for receiving the pin therein, and an outwardly-extending arm attached to a lower portion of the movable member. The locking assembly is disposable with the pin in the groove in a lowered position with the outwardly-extending arm disposed in a generally radially outward orientation operable to engage a frame supporting the manhole cover to inhibit removal of the manhole cover from the manhole frame. The locking assembly is disposable with the pin in the groove in a raised position with the outwardly extending arm disposed in a non-radially outwardly-extending orientation operable to allow removal of the manhole cover from the manhole frame.

In another embodiment, a lockable manhole cover is provided which includes, for example, a manhole cover, and the above-described locking assembly attachable to the manhole cover.

In another embodiment, a method is provided which includes, for example, providing the above noted locking assembly attached to the manhole cover in the second or raised position, positioning the manhole cover on a rim of the manhole frame, and moving the locking assembly to the first or lowered position to lock the manhole cover to the manhole frame.

In another embodiment, a method is provided which includes, for example, positioning a manhole cover disposed on a rim of a manhole frame, simultaneously downwardly moving and rotating an arm away from a bottom surface of the manhole cover so that the arm is engageable with the manhole frame to inhibit removal of the manhole cover from the manhole frame, and simultaneously upwardly moving and rotating the arm toward the bottom surface of the manhole cover so that the manhole cover is removable from the manhole frame.

DETAILED DESCRIPTION

The present disclosure and certain features, advantages, and details thereof, are explained more fully below with reference to the non-limiting embodiments illustrated in the accompanying drawings. Descriptions of well-known materials, fabrication tools, processing techniques, etc., are omitted so as to not unnecessarily obscure the disclosure in detail. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the present disclosure, are given by way of illustration only, and are not by way of limitation. Various substitutions, modifications, additions and/or arrangements within the spirit and/or scope of the underlying concepts will be apparent to those skilled in the art from this disclosure. Reference is made below to the drawings, which are not drawn to scale for ease of understanding, wherein the same reference numbers used throughout different figures designate the same or similar components.

As described in greater detail below, the present disclosure provides apparatus and methods for securing a manhole cover to a manhole frame.

FIG. 1illustrates a manhole cover10disposed or positioned on a manhole frame100with manhole cover10and manhole frame100releasably securable to each other via a plurality of locking assemblies200according to an embodiment of the present disclosure. In this illustrated embodiment, two locking assemblies200may be diametrically arranged and fitted to apertures disposed in manhole cover10. Locking assemblies200, one of which is shown inFIG. 2, may be disposable in a first or lowered position having an arm500disposed in a generally radially outward orientation relative to manhole cover10(FIG. 1) and operable to engage manhole frame100(FIG. 1) as described below. Locking assembly200may also be disposable in a second or raised position such as shown inFIG. 3with arm500rotated and disposed in a non-radially outward orientation relative to manhole cover10(FIG. 1) and operable to allow removal of the manhole cover10(FIG. 1) from manhole frame100(FIG. 1).

With reference toFIG. 4, manhole frame100may include an upper rim110, a lower smaller inset rim120that supports the manhole cover, an angled sidewall130, a lower support140, and a plurality of gussets150. Manhole frame100may define a circular opening160therethough. Manhole frame100may be set flush with a paved surface such as a street or parking lot as is known in the art. Manhole frame100may be metal casting such as cast iron.

As shown inFIG. 5, manhole cover10may be an open grate cover having a plurality of elongated openings20and a central opening30. Manhole cover10may include a peripheral edge portion12sized to be received in rim110(FIG. 4) and be supported on inset rim120(FIG. 4) of manhole frame100(FIG. 4). Manhole cover10may include a plurality of openings40(further shown inFIG. 6) diametrically arranged adjacent to peripheral edge portion12, each of which for supporting a respective locking assembly. Manhole cover10may be metal casting such as cast iron, or formed from a glass-reinforced plastic, other composite material, or other suitable material or combination thereof. While reference is made to the locking assemblies of the present disclosure being installed in a new manhole cover, it will be appreciated that the locking assemblies of the present disclosure may be installed and operable with existing manhole covers and manhole frames, e.g., retrofitted for use in existing manhole covers and manhole frames.

FIG. 7illustrates an exploded view of one of locking assemblies200. Locking assembly200may generally include a movable member300such as a rod, a bushing400, and a dog or arm500. Bushing400may include a sidewall410having an outwardly-extending flange420and external threads415. A nut600having internal threads may be threaded on external threads415of bushing400to attach locking assembly200to manhole cover10(FIG. 1). Arm500may include a proximal end510having an aperture515therein sized for receiving a lower end310of movable member300which may be fixedly secured together with a pin520. The outer surface portion of movable member300may include a recessed groove320having a spiral, helix, or curved recessed grooved portion322and a generally straight longitudinally-extending recessed grooved portion324. The outer surface portion of movable member300may also include a circumferentially extending groove390adjacent end310of movable member300. Movable member300may include an upper enlarged head330, which is receivable in and supportable in bushing400. A threaded pin470is received in and extends through a threaded hole in sidewall410of bushing400. As described below, an end of threaded pin470is slidably receivable in groove320of movable member300. A movable detent480such as a ball nose spring plunger having external threads extends through a threaded hole in sidewall410of bushing400. As described below, a biased ball at the end of ball nose spring plunger is releasably receivable in circumferentially extending groove390of movable member300. While movable member300and arm500are illustrated as separate pieces that are fixedly secured together, it will be appreciated that a locking assembly may have a movable member and arm which are integral, one-piece, or monolithic structure.

A swivel700is operably connected to movable member300with a nut750. Swivel700allows an operator to grasp locking assembly200with a hook, and also so that the operator need not have to rotate movable member300during extraction or removal of manhole cover10(FIG. 1) from manhole frame100(FIG. 1). For example, the swivel may have an eye or loop710for receiving the hook. An end720of swivel700may be secured in a passageway in movable member300by nut750allowing loop710to be rotatable. The movable member, arm, bushing, swivel, and nuts may be formed from steel or other suitable material.

As further shown inFIG. 8, bushing400may have a generally hollow cylindrical configuration. For example, bushing400may include sidewall410defining a cavity412therein have a first diameter D1, outwardly-extending rim420, and a bottom wall430having an opening440therein having a second diameter D2sized smaller than first diameter D1so that bottom wall430forms a stop435. Threaded holes extend through bottom wall430, one for receiving threaded pin470and the other for receiving ball nose spring plunger480.

FIG. 9further illustrates movable member300. For example, movable member300may have a generally hollow configuration. Upper enlarged head330may have a cavity332therein having a diameter sized for receiving loop710(FIG. 7) of swivel700. A lower portion of movable member300may have a cavity333therein. Disposed between cavities332and333may be reduced diameter passageway350sized for receiving end720(FIG. 7) of swivel700(FIG. 7). Cavity333may be sized so that nut750(FIG. 7) is easily received therein and attached to end720(FIG. 7) of swivel700(FIG. 7). A lower portion of upper enlarged head330may define a stop335which is supported on stop435(FIG. 8) of bushing400(FIG. 8).

As described above, withdrawing the movable member of locking assembly upwardly relative to the bushing and the manhole cover, or lowering the movable member of the locking assembly and relative to the bushing and manhole cover causes a rotation of the movable member and the arm.

With reference toFIG. 10,FIG. 10illustrates two locking assemblies200attached to manhole cover10in which locking assemblies200are disposed in a lowered locked position. The two locking assemblies may be diametrically arranged and fitted to apertures disposed in the manhole cover which manhole cover may be a new cover or an existing cover. It will be appreciated that in other embodiments, only one locking assembly200may be employed for locking and releasably locking manhole cover10to manhole frame100. For example, a fixed non-movable locking member may be attached to manhole cover, e.g., in place of the locking assembly disposed on the left as shown inFIG. 10. In another example, a manhole cover may be formed with a fixed non-movable locking member, e.g., in place of the locking assembly disposed on the left as shown inFIG. 10

FIG. 11illustrates locking assembly200along with a portion of the manhole cover ofFIG. 10, in which the locking assembly is disposed in a lowered locked position. Bushing400is fitted in aperture40(FIG. 6) and secured with nut600. In other embodiments, a bushing may be welded to a manhole cover. Where the manhole cover is a non-metallic cover, a bushing may be suitably bonded with a suitable bonding material. The bushing provides a transition from manhole cover10to and for receiving movable member300. Bushing300may make the locking assembly adaptable to any cover.

The weight of the locking assembly of about 7 pounds to about 13 pounds, or about 10 pounds, results in the locking assembly being disposed in a generally lowered locking position under the influence of gravity. In some embodiments, bushing400as shown inFIG. 8may have a peening land475and upper enlarged head330(FIG. 3) of movable member300(FIG. 3) may have an accompanying groove or cutout355(FIG. 3). If the manhole cover needs to be secured against unauthorized access, either from above or below grade, a portion (e.g., 2, 3, 4 or more portions) thereof land475on bushing400may be peened into cutouts355(FIG. 3) of movable member300(FIG. 3). This prevents the movable member from being withdrawn from the bushing. The peened metal may need to be ground away or otherwise removed or forced from the cutouts in order to withdraw the movable member and remove the manhole cover from the manhole frame.

In the lowered locking position, pin470is disposed in an upper spiral or helix groove portion322of groove320of movable member300so that arm500is disposed in a radially outward direction relative to manhole cover10. The length L of arm500and the height H of movable member300are sized and selected so that a distal end550will engage manhole frame100if manhole cover10is raised more than a certain vertical distance V as best shown inFIGS. 12 and 13. In some embodiments, in the lowered locked position, radially disposed distal end550of arm500may extend past the peripheral edge of the manhole cover. In other embodiments, if the manhole frame includes structure disposed inward from the peripheral edge of the manhole cover, radially disposed distal end510of arm500need not extend past the peripheral edge of the manhole cover in the lowered locked position. As further described below, this feature provides an outlet for explosive energy that might otherwise fracture the manhole cover resulting in projectiles.

With reference again toFIG. 11, when the locking assembly is disposed in a lowered locked position, a top portion of movable member300may be generally level or flush with a top surface of manhole cover10and arm300may be disposed in a position to engage manhole frame100and prevent the cover from being removed. For example, arm500may be disposed at a first distance Y1and a first radial orientation relative to a bottom surface of manhole cover10. Authorized personnel can tell at a glance whether the cover is properly secured, e.g., by the top of the locking assembly being level with the top of the manhole cover.

As shown inFIG. 14, raising movable member300of locking assembly200forces movable member300to rotate about 90 degrees (e.g., groove320moving along pin470) moving arm500inwardly toward the center of manhole cover10and away from engagement with manhole frame100and allowing manhole cover10to be removed, for example as shown inFIG. 15. For example, arm500may be disposed at a second distance Y2and a second non-radial orientation relative to a bottom surface of manhole cover10. Second distance Y2may be less the first distance Y1(FIG. 11) A standard lifting hook typically used to pull a manhole cover out of a manhole frame may be used to engage and apply an upward force F on swivel700to raise swivel700, and thus raise, apply an upward force on movable member300. Therefore, no additional or special tools are required to remove the manhole cover from the manhole frame. The manhole cover may be easily and safely removed even under emergency conditions such as a steam leak or fire below. Utility personnel can stand safely away from the manhole cover but sufficiently close to reach it with a standard hook tool, operate the lock(s), and remove the manhole cover from the manhole frame with one or two motions.

With reference again toFIG. 14, a portion of groove320may have about a 90 degree spiral, helix, or curved groove322(FIG. 7) that allows movable member300to rotate about 90 between the raised unlocked position and the lowered locked position.

With reference again toFIG. 8, a biased ball at the end of ball nose spring plunger480is releasably receivable in circumferentially extending groove390(FIG. 9) of movable member300to maintain locking assembly200as shown inFIG. 14in a raised unlocked position. Maintaining locking assembly200in a raised unlocked position results in arm500generally not being engageable with the ground when the cover is removed and placed on the ground. As shown inFIG. 8, the end of pin470may be sized larger than the end of ball nose spring plunger480so that pin470remains disposed in groove320in both the lowered and raised positions. The groove may have a long straight portion beyond the spiral, helix, or curved portion enabling the pin to remain engaged with the groove throughout the range of operation. This feature maintains the alignment of the movable member relative to the bushing, and thus, relieves the operator of the need to align the movable member and arm relative to the manhole cover when locking and unlocking the manhole cover form the manhole frame.

FIG. 16illustrates a method800according to an embodiment for locking and unlocking a manhole cover to a manhole frame. Method800may include at810positioning a manhole cover disposed on a rim of a manhole frame, at820simultaneously downwardly moving and rotating an arm away from a bottom surface of the manhole cover so that the arm is engageable with the manhole frame to inhibit removal of the manhole cover from the manhole frame, and at830simultaneously upwardly moving and rotating the arm toward the bottom surface of the manhole cover so that the manhole cover is removable from the manhole frame.

As will be appreciated, the present disclosure may provide a secure manhole covers and methods that are simple, rugged, retrofittable, provides an obvious indication of engagement, and allows explosion products to escape. Some currently available devices require that the embedded manhole frame be replaced as well as the cover, making the transition very expensive and time consuming. Other approaches are complicated and prone to failure or seizing.

As described above, a spring device or biased detent may be included to hold the locking movable member in a raised unlocked position. This ensures that the movable member (movable members, for example, when two locking assemblies are used for a manhole cover) will not interfere with removing the cover from the hole, and also protect the locking assembly from damage when the cover is dragged away from the hole. When an unlocked manhole cover is placed on a manhole frame, the movable member may transition to the lower locked position with a slight tap on the movable member, e.g., disengage the spring device or biased detent from the circumferentially extending groove390(FIG. 7).

As described above, the spiral, helix, or curved groove is disposed in the movable member and the pin that rides in the groove is disposed in the bushing. The bushing has two threaded holes, one for a pin that rides in the groove, and one for a ball spring plunger that engages a circumferential groove in the movable member, e.g., as described above. For example, a ball spring plunger is operable to hold the movable member in a raised unlocked position. The ball spring plunger may be employed for restraining the movable member in a lower position, however the weight of the locking assembly may be sufficient for maintaining the locking assembly in the lower locked position. In other embodiments, a locking assembly may have a bushing or a sleeve therein with a spiral, helix or curved cutout or groove, and a movable member may have pin that extends outwardly from the movable member. Such a pin and groove may allow the locking assembly to be positioned in a lowered locked position or a raised unlocked position by the pin riding in the groove.

As will be appreciated from the description above, any cover, regardless of material or size, may be fitted with one or a plurality of locking assemblies of the present disclosure. For example, the apertures may be holes that are cut into existing manhole covers or holes formed as part of a pattern of a new cast manhole cover.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments and/or aspects thereof may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from their scope.

While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

While the disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that aspects of the disclosure may include only some of the described embodiments. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

This written description uses examples in the present disclosure, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.