Manhole cover assembly

A manhole cover assembly includes a manhole cover and a latch assembly. The manhole cover is supportable by a seat of a manhole frame. The latch assembly includes a latch housing fixedly coupled to the manhole cover. A latch plunger is slidably coupled to the latch housing. The latch plunger includes a follower arm. A latch lever is rotatably coupled to the latch housing. The latch lever includes a stop. The latch lever is rotatable relative to the latch housing between a locked position and an unlocked position. The stop is structured to engage the manhole frame when the latch lever is rotated to unlocked position so as to force the manhole cover away from the frame.

TECHNICAL FIELD

The present disclosure relates generally to the field of manhole and hatch cover assemblies.

BACKGROUND

A manhole provides access to an underground passage or confined area. The underground passage or confined area may contain public utility equipment, such as sewer lines, storm drains, electrical and telecommunication cables, etc. A manhole or hatch cover is a removable plate that forms a lid over the opening of a manhole. Manhole covers are used to prevent individuals and objects from falling into the manhole, as well as to prevent unauthorized access into the manhole. The terms “manhole cover” as used herein to mean either a manhole cover, or a hatch cover, and the like.

Manhole covers are conventionally formed of cast iron, which makes them inexpensive, strong, and heavy, usually weighing more than 100 pounds. The weight helps to keep them in place when traffic passes over them, and makes it difficult for unauthorized individuals to remove them. In addition to being constructed of cast iron, manhole covers may also be constructed of concrete, glass-reinforced plastic or other composite materials, and other materials, or any combination thereof

Despite their significant weight, manhole covers can be dislodged in several ways. For example, an explosion within a manhole can cause a sudden pressure buildup that can dislodge the manhole cover. For example, gases (e.g., methane from sewage or natural gas from a leaking natural gas line) can become trapped in the space within the manhole, as well as within the passages or spaces connected to the manhole. The gas may be ignited, for example, due to a spark from a frayed power cable. Some explosions generate sufficient pressure to dislodge the manhole from its frame. However, higher-intensity explosions may propel the manhole cover up to 20 feet or more into the air. A heavy manhole cover flying through the air can be extremely dangerous or deadly. In addition to the human and property damage risk, individuals or objects may subsequently fall into the now-uncovered manhole.

Excessive rainfall and flooding can also dislodge manhole covers. For example, storm drain systems may become overfilled during periods of excessive rainfall. Water may flow through the storm drain systems and up through a manhole. Sufficient pressure from the water may dislodge manhole covers and “float” them away. The now-uncovered manhole can be obscured by dirty water, thereby providing a dangerous risk that an unwary victim may inadvertently fall into the manhole and into the storm drain system.

SUMMARY

Various embodiments relate to manhole cover assemblies. An example manhole cover assembly includes a manhole cover and a latch assembly. The manhole cover is supportable by a seat of a manhole frame. The latch assembly includes a latch housing fixedly coupled to the manhole cover. A latch plunger is slidably coupled to the latch housing. The latch plunger includes a follower arm. A latch lever is rotatably coupled to the latch housing. The latch lever includes a stop. The latch lever is rotatable relative to the latch housing between a locked position and an unlocked position. The stop is structured to engage the manhole frame when the latch lever is rotated to unlocked position so as to force the manhole cover away from the frame.

DETAILED DESCRIPTION

Various events, such as explosions or flooding, can cause a sudden pressure increase beneath a manhole cover, which can force the manhole cover from its frame. Several manhole cover assemblies have been developed to release pressure buildup from beneath a manhole cover while limiting displacement of the manhole cover relative to its frame. For example, some manhole cover assemblies include legs or other features to permit limited displacement of the manhole cover. During a pressure-inducing event, the legs contact a bottom surface of the frame, thereby limiting travel of the manhole cover. However, the kinetic energy of the rising manhole cover is concentrated into relatively small areas of the frame surface that are contacted by the legs. Accordingly, significant pressure-inducing events, such as explosions or floods, may damage the frame. This is undesirable because the frame is typically cemented or otherwise permanently fixed in a street or roadway, and removal and replacement of the frame is a significant and costly undertaking.

FIG. 1is a cross-sectional perspective view of a manhole cover assembly100, according to an embodiment. It should be noted that for clarity and brevity, embodiments are described herein as relating to manhole cover assemblies. However, embodiments described herein may also be utilized in conjunction with hatch covers or other types of covers. As shown inFIG. 1the manhole cover assembly100includes a manhole cover102, a latch assembly104, and a lug assembly106. The manhole cover102is generally disc-shaped, having a top surface108, a bottom surface110and an outer periphery112. The latch assembly104and the lug assembly106are each securely coupled (e.g., bolted, welded, etc.) to the bottom surface110of the manhole cover102. The latch assembly104includes a latch114extending radially outward from the latch assembly104. Similarly, the lug assembly106includes a lug116extending radially outward from the lug assembly106.

A frame118is configured to support the manhole cover102over the opening of a manhole (not shown). The frame118is fixedly secured (e.g., cemented or otherwise fixed) within a substrate (e.g., street, road, sidewalk, etc.) defining the opening of the manhole (not shown). The frame118is generally ring-shaped, having a peripheral wall120extending between an upper surface122and an opposite lower surface124. The peripheral wall120has an inner diameter that is slightly larger than an outer diameter of the manhole cover102. In operation, the upper surface122of the frame118is generally flush with the road or other surface that defines the manhole.

The frame118also includes a projection126that extends radially inward from the peripheral wall120. The projection126defines a seat127facing longitudinally outward toward the upper surface122, and defines a catch129facing longitudinally inward toward the lower surface124. The seat127is structured to support the manhole cover102within the frame118. More specifically, the bottom surface110of the manhole cover102proximate the outer periphery112rests on, and is supported by, the seat127when the manhole cover is in a seated position. The top surface108of the manhole cover102is generally flush with the upper surface122of the frame118when the manhole cover102is in the seated position. The catch129is structured to be engaged by the each of the latch114and the lug116during a pressure-inducing event so as to retain the manhole cover102, while controllably dissipating pressure from within the manhole.

FIG. 2is a bottom perspective view of the manhole cover assembly100ofFIG. 1, with the manhole cover102in the seated position. As shown inFIG. 2, when the manhole cover102is in the seated position, as is typically the case, there is a gap between the lower surface124of the frame118and each of the latch114and the lug116. A sudden pressure increase against the bottom surface110of the manhole cover102can cause the manhole cover102to move relative to the frame118from the seated position (e.g., as shown inFIG. 2) to the unseated position (e.g., as shown inFIG. 1). Returning toFIG. 1, it can be seen that in the unseated position, the latch114and the lug116each contact the lower surface124of the frame118. Accordingly, the latch and lug assemblies104,106are configured to limit displacement of the manhole cover102during a pressure-inducing event in which the manhole cover102is forced to the unseated position.

The latch and lug assemblies104,106are also configured to controllably dissipate pressure from within the manhole during a pressure-inducing event. As discussed in further detail below, the latch and lug assemblies104,106permit the energy from a pressure-inducing event (e.g., an explosion or flood) to move the manhole cover102from the seated position to the unseated position. When in the unseated position, high-pressure fluid (e.g., air or water) and debris may escape from the manhole through the space then available between the manhole cover102and the frame118, proximate the outer periphery112of the manhole cover102and the projection126of the frame118. Thus, in response to a pressure-inducing event, the latch and lug assemblies104,106of the manhole cover assembly100operate to controllably release pressure from within a manhole rather than allowing the pressure to build up beneath the manhole cover102to a potentially dangerous level. In doing so, the latch and lug assemblies104,106prevent the manhole cover102from being launched from the frame118by a pressure-inducing event, while also preventing damage to the frame118and the surface (e.g., street) to which the frame is secured.

The manhole cover assembly100also includes extractor rails113fixedly coupled (e.g., welded) to each of the manhole cover102and the lug assembly106so as to form a gradual ramp from the lug116to the bottom surface110of the manhole cover102. The extractor rails113facilitate easy removal of the manhole cover102from the frame118. In particular, as the manhole cover102is pulled away from the frame118, extractor rails113slide against the upper surface122of the peripheral wall120of the frame118. Upon the manhole cover102being completely removed from the frame118, a skid pad115affixed (e.g., bolted) to a bottom surface111of the lug assembly106contacts the outer surface (e.g., roadway). The skid pad115may be formed of high molecular weight polyethylene (HMWP), Teflon, rubber, or other materials.

As illustrated inFIG. 2and as discussed further in connection withFIGS. 3-6, the latch assembly104includes a latch housing128. As will be appreciated, the latch housing128is structured to support and retain the various components of the latch assembly104. As illustrated inFIGS. 1 and 2, the latch housing128is fixedly coupled (e.g., welded) to the bottom surface110of the manhole cover102.

FIG. 3is a cross-sectional view of the latch assembly104ofFIGS. 1 and 2. The latch assembly104includes the latch housing128, a latch plunger130, and a latch lever132. The latch plunger130is disposed within and is slidably coupled to the latch housing128. The latch plunger130defines the latch114. The latch lever132is disposed at least partially within, and is operatively coupled to the latch housing128via a latch bolt133. As will be appreciated, the latch lever132may be operated by a user to engage, and thereby actuate, the latch plunger130.

In one embodiment, as shown inFIGS. 1-3, the latch housing128includes an inner wall134, a first lateral wall136(FIG. 3), a second lateral wall138(FIG. 2) and a bottom wall140, which together form the latch housing128. In one embodiment, the inner wall134, the first and second lateral walls136,138, and the bottom wall140are formed of metal (e.g., steel, iron, aluminum, any alloys thereof, etc.) plates or sheet metal, which are welded together to form the latch housing128. In other embodiments, the inner wall134, the lateral walls136, and the bottom wall140are formed of cast metal (e.g., steel, iron, aluminum, any alloys thereof, etc.), stamped sheet metal (e.g., steel or aluminum), and injection molded polymer to form the latch housing128.

As shown inFIG. 3, the first lateral wall136defines a slot-shaped opening142and a slot-shaped boss144extending into the latch housing128from the first lateral wall136. Although not shown, the second lateral wall138may also include a corresponding slot-shaped opening142and slot-shaped boss144. The inner wall134defines a latch rod opening146that extends through the inner wall134proximate the bottom wall140. A ledge148extends from the inner wall136into the latch housing128at an upper-most end of the inner wall136adjacent the bottom surface110of the manhole cover102. The ledge148is structured to support the latch lever132when the latch lever132is in a disengaged position, as shown inFIG. 3.

As shown inFIGS. 1 and 3, the latch housing128defines a top opening150and an outer radial opening152. The top opening150is positioned proximate a corresponding latch opening154defined by the manhole cover102. The latch opening154permits access to the latch lever132, which extends through the top opening150of the latch housing128, so as to enable a user to operate the latch114. The latch114of the latch plunger130extends through the outer radial opening152to engage the catch129so as to retain the manhole cover102within the frame118. In some embodiments, the latch housing128includes an outer peripheral wall that defines an opening through which the latch114may extend.

As shown inFIGS. 2 and 3, the first and second lateral walls136,138and the bottom wall140of the latch housing128each define vents156. According to various embodiments, one or more of the inner wall134, the first and second lateral walls136,138, and the bottom wall140may define vents156. The vents156permit fluids (e.g., water) and debris to exit the latch housing128, should fluids and/or debris enter the latch housing128, e.g., via the top and/or outer radial openings150,152.

FIG. 4is a top perspective view of the latch plunger130ofFIGS. 1-3. The latch plunger130includes a latch rod158and a latch member160extending from the latch rod158along a longitudinal axis162of the latch rod158. The latch rod158may include a threaded end164opposite the latch member160. The latch member160includes a first face166defining a plane parallel to the longitudinal axis162, and a second face168opposite the first face166. The first face166defines the latch114and the second face168defines a ramp170, which curves towards the first face166, extending through the longitudinal axis162. The latch member160defines a pocket172extending radially inward from the first face166towards the longitudinal axis162. A follower arm174extends radially outward from the first face, adjacent each of the latch rod158and the pocket172.

FIG. 5is a top perspective view of the latch lever132ofFIGS. 1-4. The latch lever132includes an elongate latch lever member176that extends generally along a longitudinal axis178between a first end180and a second end182, and defining a top surface184and an opposite bottom surface186. An actuating arm188extends from the bottom surface186generally perpendicular to the longitudinal axis178, defining an actuating end190. A pivot arm192extends longitudinally outward from the actuating arm between the bottom surface186and the actuating end190. A pivot boss194is formed at an end of the pivot arm192. The pivot boss194defines a pivot bore196having a pivot axis198perpendicular to the longitudinal axis178. The pivot boss194is structured to receive the latch bolt133via the pivot bore196. The pivot boss194is structured so as to abut the slot-shaped bosses144of each of the first and second lateral walls136,138when the latch lever132is installed in the latch housing128.

The latch lever132also defines a stop200that extends from the first end180of the latch lever member176. The stop200includes an outer extraction surface202. As discussed further in connection withFIG. 6, the outer extraction surface202is structured to contact the seat127and the inner surface of the peripheral wall120of the frame118when the manhole cover102is being extracted from the frame118. As shown inFIG. 5, the outer extraction surface202can be rounded or can include other cam-shaped profiles so as to facilitate extraction of the manhole cover102from the frame118.

The latch lever member176defines a first bore204extending through the latch lever member176along a first bore axis206, from the top surface145to the bottom surface147. The first bore axis206is positioned at an angle α relative to the longitudinal axis178of the latch lever member176. In one embodiment, α is 30 degrees. In another embodiment, α is 45 degrees. In various other embodiments, α is any of less than 30 degrees, between 30 and 45 degrees, and between 45 and 90 degrees. As discussed further in connection withFIG. 6, the first bore204is structured to receive a lifting tool (not shown), such as a pick or a hook, for example.

The latch lever132also defines a second bore208extending through the latch lever member176proximate the second end182along an axis perpendicular to the longitudinal axis178. As shown inFIG. 5, the second bore208may include a counter bore. According to an embodiment, the second bore208is structured to receive a retaining bolt (not shown) to securely couple the latch lever member176to the manhole cover102in a locked position, as discussed further in connection withFIG. 6. According to various embodiments, the retaining bolt may include a pentagonal (5-sided) head or other non-standard bolt head configurations so as to deter unauthorized tampering and vandalism. In other embodiments, the retaining bolt may include a standard hexagonal (6-sided) head or other bolt head configurations.

Turning back toFIG. 3, assembly and operation of the latch assembly104, including the latch plunger130ofFIG. 4and the latch lever132ofFIG. 5will now be described. The latch plunger130is disposed within the latch housing128, with the second face168of the latch member160abutting an interior face of the bottom wall140of the latch housing128. The latch rod158extends through the latch rod opening146of the inner wall134of the latch housing128. The latch rod158extends through a latch spring210disposed within the latch housing128. As shown inFIG. 3, the latch rod158is structured such that there is clearance between the latch rod158and the bottom wall140of the latch housing128when latch plunger130is installed within the latch housing128, so as to accommodate the latch spring210. In operation, the latch spring210is compressed between an interior face of the inner wall134of the latch housing128, and the follower arm174of the latch plunger130. A nut212(and a washer in some embodiments) is attached to the threaded end164of the latch rod158extending through the latch housing128. The nut212is tightened so as to move the latch114towards an interior of the latch housing128and compress the latch spring210. In other words, tightening the nut212moves the latch114radially inward and away from the catch129of the frame118(FIG. 1). In operation, the latch assembly104may be adjusted via the nut212so as to ensure that operating the latch lever132sufficiently moves the latch114so as to clear the catch129.

As discussed briefly in connection withFIG. 5, the latch lever132is supported on the ledge148when the latch lever132is in a disengaged position. The ledge148defines a ledge bore214, which is structured to receive a fastener (not shown) so as to securely couple the latch lever132to the latch housing128, and therefore, to securely couple the latch lever132to the manhole cover102. Upon assembly, the actuating arm188of the latch lever132abuts the follower arm174of the latch plunger130.

FIG. 6is a partial cross-sectional view of the manhole cover assembly100ofFIGS. 1 and 2, illustrating the manhole cover102being removed from the frame118. As mentioned, a pick or lifting tool (not shown), may be used to rotate the latch lever132upwards from the top surface108of the manhole cover102. Upon the latch lever132being operated by a user, the latch lever132slides relative to the latch housing128via the latch bolt133sliding within the slot-shaped opening142so as to move the latch bolt133against the radially outward-most surface of the slot-shaped opening142. As the latch lever132is further engaged, the latch lever132pivots about the latch bolt133so as to rotate relative to the latch housing128.

Further rotation of the latch lever132, while pivoting on the latch bolt133results in two actions. First, the actuating arm188presses against the follower arm174, thereby sliding the latch plunger130so as to compress the latch spring210and move the latch114away from the frame118and into the latch housing128. Second, rotation of the latch lever132causes the outer extraction surface202of the stop200to contact the seat127and the inner surface of the peripheral wall120of the frame118. As the latch lever132is rotated, the contact between the stop200and the frame118forces the latch bolt133upwards and radially outwards against the slot-shaped opening142. Accordingly, the force exerted on the slot-shaped opening142of the latch housing128causes the manhole cover102to move upward and radially outward from the frame118. The lever arm created by the latch lever132further operates to amplify the input force imparted on the latch lever132to produce an even greater output force against the latch housing128. Thus, the latch assembly104facilitates easy removal of the manhole cover102from the frame118such that a single individual can remove the manhole cover102himself or herself.

As the manhole cover102is pulled away from the frame118, the extractor rails113(FIG. 1) slide against the upper surface122of the peripheral wall120of the frame118. As the manhole cover102is completely removed from the frame118, the skid pad115affixed to a bottom surface111of the lug assembly106contacts the outer surface (e.g., roadway).

It is important to note that the construction and arrangement of the system shown in the various example implementations is illustrative only and not restrictive in character. All changes and modifications that come within the spirit and/or scope of the described implementations are desired to be protected. It should be understood that some features may not be necessary and implementations lacking the various features may be contemplated as within the scope of the application, the scope being defined by the claims that follow. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary.