Patent Publication Number: US-7905679-B2

Title: Dual lifting manhole cover

Description:
BACKGROUND OF THE INVENTION 
     The present application relates to manhole cover assemblies, and, more particularly, to a manhole cover with dual lifting ports. 
     Manholes are well-known and widely utilized. Generally, a manhole provides access for maintenance of infrastructure, for instance, underground pipelines or cabling. Traditional manhole covers rest on a frame that is attached to the substructure above infrastructure to be maintained. Examples of such substructure include the base for a road or sidewalk. The cover rests on this frame and must be lifted away to gain access to the infrastructure beneath the manhole. Because manhole covers are predominantly made of iron and can weigh in excess of 100 pounds, the effort required to lift a manhole cover can be difficult and even injurious to the operator. 
     Many attempts have been made to ease the effort required to lift a manhole cover from its frame. For example, some manhole covers include a hole extending through the cover. To lift the cover, an operator inserts a pointed tool through the hole to either pry up or lift the cover. This method provides some additional lifting leverage, but the hole in the cover provides direct access for external contaminants to drain below to the infrastructure. 
     Other manhole covers include a lifting insert within the upper face of the cover. These lifting inserts are typically cast inserts that are placed in a recess in the face of the cover. The inserts define a cutout in the face of the cover, and they include a bar that extends over the cutout such that a pointed tool could be wedged underneath or against the bar to provide lifting leverage. The cutout is typically symmetrical in shape, and it typically does not extend completely through the insert to prevent external contaminants from draining through the cover. To open such a cover, an operator wedges a tool into the cutout and underneath or against the bar, and applies a force on the bar, lifting the cover away from the frame. This type of cover prevents outside contaminants from draining directly into the infrastructure, but new problems arise due to runoff and other debris that tend to collect in the cutout. Thus, an operator may be required to clear out the cutout prior to opening the cover. In addition, installing an insert in this way may generate increased manufacturing costs because of the additional steps necessary to fabricate such a cover. 
     SUMMARY OF THE INVENTION 
     The aforementioned problems are overcome by the present invention wherein a one-piece, unitary manhole cover is provided with a channel that defines a cutout in the upper face of the cover and that extends through the outer edge of the cover. A lifting bar bridges the channel and forms two separate openings in the upper face of the cover. The channel and the lifting bar are configured to form dual lifting ports, one on each side of the lifting bar, that enable easy removal of the cover by prying or lifting. 
     In one embodiment, a first end of the lifting channel and a first sidewall of the lifting bar cooperate to define an ergo lifting port that receives a lifting tool. The second end of the channel and a second sidewall of the lifting bar cooperate to define a pry bar lifting port. The pry bar lifting port may be located at the outer end of the channel, and may extend through the outer circumferential edge of the cover. In one embodiment, the ergo lifting port includes an arc-shaped portion of the lifting channel floor, and a lobe extending downwardly from the lower surface of the lifting bar. The portion of the floor and the lobe cooperate to receive and provide leverage for a lifting tool. In one embodiment, the pry bar lifting port includes a generally planar portion of the lifting channel floor and a generally planar portion of the lower surface of the lifting bar. The generally planar surfaces cooperate to receive and provide leverage for a pry tool. 
     The present invention provides a one-piece manhole cover that facilitates removal of the cover using either a specially designed lifting tool or a conventional, widely accessible pry bar lifting tool, allowing the operator to easily and efficiently open the cover. The floor of the channel prevents contaminants such as dirt and garbage from draining into the infrastructure below the manhole. Further, by extending through the outer circumferential edge of the cover, the channel allows contaminants to drain out of the channel through the outer edge of the cover. 
     These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the current embodiment and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partial side cross sectional view of the cover as received into a frame according to one embodiment of the present invention. 
         FIG. 2  is a side cross sectional view of cover lifted from the frame using the ergo lifting port. 
         FIG. 3  is a side cross sectional view of the cover partially removed from the frame using the ergo lifting port. 
         FIG. 4  is a side cross sectional view of the cover with a pry toll inserted in the pry bar lifting port, and showing the cover lifted from the frame using the pry bar lifting port in broken lines. 
     
    
    
     DESCRIPTION OF THE CURRENT EMBODIMENT 
     A manhole cover in accordance with one embodiment of the present invention is illustrated in the drawings and designated  10 . In illustrated embodiment, the cover  10  has a lower face  12 , an upper face  14 , an outer circumferential edge  16  and at least one channel  18  defined in the upper face and extending to the outer circumferential edge  16 . In one embodiment, the channel  18  is divided by a lifting bar  24  to define an ergo lifting port  20  and a pry bar lifting port  22 . In operation, as illustrated in  FIGS. 2-4 , the cover  10  can be removed from the frame  26  in multiple ways, for instance, by inserting an ergo lifting tool  60  into the ergo lifting port  20  or a pry bar  70  into the pry bar lifting port  22 . The channel  18  extends through the outer circumferential edge and provides means for fluid and debris to drain from the lifting channel  18 . 
     In the illustrated embodiment, the cover  10  is a cast iron cover of an overall disc-shaped geometry. In other embodiments, the cover  10  could be of another geometry, and another material. In one embodiment, the entire cover  10  is formed from the same material, such that the material forming the channel  18  and lifting ports  20  and  22  is unitary with the material of the surrounding areas of the cover  10 . In one embodiment, the channel  18 , lifting bar  24  and lifting ports  20 ,  22  may be fabricated using a core within the overall cover mold. Suitable alternative materials and fabrication methods may also be utilized. 
     As noted above, the cover  10  has a lower face  12  and an upper face  14 , and an outer circumferential edge  16 . The cover defines a thickness  21  between the upper face  14  and lower face  12 . In one embodiment, the upper face  14  may include projections and designs that indicate the owner of the cover  10 , the manufacturer, the type of infrastructure beneath the manhole or any other pattern. The lower face  12  may include a downwardly extending projection  33  extending around the cover  10  proximate the outer circumferential edge  16 , such that the thickness  21  of the cover increases proximate the outer circumferential edge  16 . 
     The cover  10  is adaptable to be received by many different frame configurations. In the embodiment illustrated in the figures, the lower face  12  of the cover  10  rests on a cover support rim  28  of a frame  26 . The frame  26  may include a frame wall  30  rising away from the substructure the frame  26  is mounted on. The frame wall  30  is an annular ring defining an inner surface  32 . The cover support rim  28  projects from the inner surface  32  of the frame wall  30 . An upper segment  34  of the frame wall  30  may extend beyond the cover support rim  28 . The upper edge  31  of the upper segment  34  may be flush with the upper surface  14  of the cover when the cover  10  is in place on the cover support rim  28 . The inside diameter of the frame wall  30  is slightly greater than the diameter of the cover  10  to provide clearance between the upper segment  34  of the frame wall  30  and the outer circumferential edge  16  of the cover  10  when the cover is installed on the frame  26 . In another embodiment, the lower face of the cover could rest directly on the annular top of the frame wall. 
     In the illustrated embodiment, the cover  10  includes at least one channel  18  that defines openings in the upper face  14  for the ergo lifting port  20  and the pry bar port  22 . The channel extends through the outer circumferential edge  16  toward the center of the cover  10 . In one embodiment, two channels  18  are disposed on opposite sides of the cover  10 . In other embodiments, one or more channels could be arranged in any configuration around the edge. The illustrated channel  18  includes a lifting bar  24  that extends across the width of the channel  18  and divides the channel  18  into the ergo lifting port  20  and the pry bar port  22 . The illustrated channel  18  extends from the outer circumferential edge to an interior end  39  in the interior of the cover  10 . 
     The channel includes a floor  52  that may be configured to receive an ergo lifting tool  60  through the ergo lifting port  20  and a pry tool  70  through the pry bar lifting port  22 . In one embodiment, the floor  52  includes an ergo lifting arc  54 , a pick leverage face  56  and a pry bar port lead in surface  58 . In the embodiment illustrated in the figures, the ergo lifting arc  54  is a smooth, arcing surface extending from the upper face  14  of the cover  10  to the pick leverage face  56 . A portion of the ergo lifting arc  54  extends below the pick leverage face  56 . The pick leverage face  56  is a generally flat surface that connects the ergo lifting arc  54  to the pry bar port lead in surface  58 . The plane of the illustrated pick leverage face  56  is parallel to the overall plane of the cover  10 . The pry bar port lead in surface  58  extends from the pick leverage face  56  to the outer circumferential edge  16  of the cover  10 . In the embodiment illustrated in the figures, the pry bar port lead in surface  58  is a ramped surface that slopes toward the upper face  14  of the cover  10  as the lead in surface  58  moves toward the outer circumferential edge  16  of the cover  10 . The outer edge  61  of the pry bar port lead in surface is below the upper face  14  of the cover to define an opening in the outer circumferential edge  16  that allows the contents of the channel  18  drain over the pry bar port lead in surface  58  and through the outer circumferential edge  16 . 
     As illustrated, the lifting bar  24  bridges the channel  18  and is spaced from the channel floor  52  to form the ceiling of the channel  18 . The upper surface  42  of the lifting bar  24  may be flush with the upper face  14  of the cover  10 . In one embodiment, an ergo lifting lobe  46  projects into the channel  18  from the lower surface  40  of the lifting bar  24 . A first sidewall  48  of the lifting bar  24  may form a portion of the lifting lobe  46  and may transition in a rounded curve to the lower surface  40  of the lifting bar  24 . A second sidewall  50  may also transition via a slightly rounded curve into the generally flat portion of the lower surface  40 . 
     The interior end  39  of the channel  18  and the lifting bar  24  cooperate to define the ergo lifting port  20 . In the illustrated embodiment, the ergo lifting port  20  is of an overall rectangular shape but the ergo lifting port  20  could be of alternate geometries to receive lifting tools  60  of various configurations. The ergo lifting port  20  is configured to receive a hook-shaped a lifting tool  60 . As shown in  FIGS. 2 and 3 , one such tool includes a handle  62 , a point  64 , an upper face  66  and a lower face  68 . In this embodiment of the tool  60 , the handle  62  makes an angle of approximately 60° with the upper face  66  and lower face  68  of the tool  60 . Various other lifting tools  60  are suitable for use with the cover  10 , and the specific configuration of the lifting sector  18  can be adapted for the geometry of various lifting tool designs. In alternative embodiments, the angle may be adjusted to accommodate alternative lifting sector configurations, frames, operator heights, etc. 
     In operation, the point  64  of the tool  60  is inserted through the ergo lifting port  20 , into the channel  18  and under the lifting bar  24 . The arc shaped portion  54  of the channel  18  allows the tool  60  to enter the channel  18  with the lower face  68  of the tool  60  pressed against the pick leverage face  56 , and the upper face  66  of the tool  60  pressed against the ergo lifting lobe  46 . The operator applies a lifting force to the handle  62  of the tool  60 , and leveraging forces are applied to the pick leverage face  56  and the ergo lifting lobe  46  allowing the operator to lift the cover  10  up and away from the frame  26 , as can be seen in  FIGS. 2 and 3 . 
     In one embodiment, the pry bar lifting port  22  is a bi-planar aperture formed at the outer end  61  of the channel  18  where the outer circumferential edge  16  and upper face  14  of the cover  10  meet. Although the hook-shaped lifting tool  60  could be used in the pry bar lifting port to pry open the cover  10 , various prying tools  70  are well-known in the art and more suitable for use with the pry bar port  22  of cover  10 . One such prying tool is illustrated in  FIG. 4 . In this embodiment, the prying tool  70  includes a lifting arm  72  that has a lower face  74  and an upper face  76 . An elbow  80  separates the lifting arm  72  from the handle  78  of the prying tool  70 . To utilize the pry bar lifting port  22 , the lifting arm  72  of the prying tool  70  is inserted through the pry bar lifting port  22 , into the channel  18  and under the lifting bar  24 . The lower face  74  presses against the pick leverage face  56  and the lead in surface  58 , and the upper face  76  presses against the second sidewall  50  of the lifting bar  24 . The operator applies a downward force to the handle  78  of the prying tool  70  causing the prying tool  70  to pivot about the elbow  80  which serves as a fulcrum. Lifting forces are then applied to the pick leverage face  56 , the second sidewall  50  and lower surface of the lifting bar  40  allowing the operator to elevate the cover  10  for removal from the frame  26  (as shown in broken lines in  FIG. 4 ). The operator may then rotate the cover away from the frame  26  to provide access to the infrastructure. The pry bar lifting port  22  is adapted to receive a range of prying tools  70  allowing operators to remove the cover  10  even if they do not have access to a tool designed specifically for removal of the particular cover  10 . 
     In alternative embodiments, the ergo lifting port and pry bar lifting port may be alternatively sized or shaped to accept different styles of tools. In other embodiments, the lifting channel could be alternatively configured as well, based on the tool to be used. One or more of the ergo lifting arc, pick leverage face, pry bar port lead in surface, rounded corners and lifting lobe could be eliminated or altered to accommodate alternate tool styles. 
     The above description is that of the current embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.