Adjustable manhole cover assembly

Abstract

An adjustable manhole cover frame assembly for mounting on a manhole basin upper section ( 12 ) has an outer ring ( 22 ) and an inner ring ( 20 ) engaging the outer ring by screw threads and supporting the manhole cover ( 10 ). The lower annular surface of the frame assembly rests on a convexly curved surface ( 36 C) of a metallic adapter ( 36 ), which in turn rests on the generally flat surface ( 12 A) of the manhole basin upper section ( 12 ); this allows the orientation of the frame assembly to be adjusted. Also, the frame assembly itself may have parts which allow its upper part to be adjusted for slope when the lower part of the frame assembly has been fixed. Another feature is a hinge mechanism ( 16 ) having a hinge arm ( 74 ) connecting two pivots ( 72,76 ), and having interlocking means ( 18 ) which prevent the hinge side of the cover from being raised when the cover is closed.

1 . An adjustable manhole cover assembly comprising;
 an adapter part ( 36 ) having a lower, annular surface portion ( 36 A) suitable for resting on a generally flat top surface ( 12 A) of a manhole top section ( 12 ), the adapter part having a part-spherical, upwardly convex metal upper surface ( 36 C),   and an adjustable frame assembly ( 14 ) having an upper, inner frame ( 20 ) movable within a lower, outer frame ( 22 ) for adjusting the height of the inner frame, and wherein the lower, outer frame has an annular lower surface ( 22 B) which forms a mating surface slidable on the upper part-spherical surface ( 36 C) of the adapter and which provides a joint between the adapter ( 36 ) and the outer frame ( 22 ).   
   
   
       2 . A manhole cover assembly according to  claim 1 , wherein the lower mating surface ( 22 B) has a slope similar to that part-spherical surface ( 36 C) of the adapter part ( 36 ). 
   
   
       3 . A manhole cover assembly according to  claim 1 , wherein the upper, inner frame ( 20 ) has an upper portion ( 20 A) and a lower portion ( 20 B) with respective mating surfaces, and at least one of these surfaces is part-spherical, whereby the upper portion ( 20 A) of the upper, inner frame ( 20 ) may be adjusted in slope relative to the lower portion ( 20 B) of the upper inner frame ( 20 ) while maintaining a sealing relationship between the last-mentioned mating surfaces. 
   
   
       4 . A manhole cover assembly according to  claim 1 , wherein said metallic adapter part ( 36 ), and said inner and outer frames ( 20 ,  22 ) are made of ductile iron. 
   
   
       5 . A manhole cover assembly according to  claim 1 , wherein at least a lower portion of said outer frame ( 22 ) is provided with a machined cylindrical metal surface, and a sealing collar ( 38 ) is provided covering said joint between the mating surfaces of the outer frame ( 22 ) and the adapter ( 36 ), said collar having means ( 42 B) for sealing against said machined lower portion of the outer frame, which sealing means allows said outer frame to slide upwardly in said collar, under the influence of frost-heave or like forces lifting the outer frame, while maintaining a seal over said joint. 
   
   
       6 . A manhole cover assembly according to  claim 1 , comprising a hinge mechanism ( 16 ) for connecting one side of a manhole cover ( 10 ) to said inner frame ( 20 ), and having locking means ( 18 ) for locking the other side of the cover ( 10 ) to the inner frame ( 20 ), said hinge mechanism comprising;
 bracket means ( 70 ) fixed to an inner surface of said inner frame ( 20 ) and positioned to be covered by the cover ( 10 ) when closed, said bracket means supporting a pivot ( 72 );   a hinge arm ( 74 ) having an inner end carried by said pivot;   further pivot means ( 76 ) connecting an outer end of the hinge arm to the underside of the cover ( 10 );   a downwardly facing cam surface ( 68 A) carried by said upper, inner frame ( 20 ) adjacent to said bracket means ( 70 ); and   a locking element ( 82 ) carried by the underside of said cover and positioned so that, in the closed position of the cover, said locking element fits against the underside of said cam surface ( 68 A) and prevents the hinge side of the cover from being raised when the other side of the cover is held closed by said locking means.   
   
   
       7 . A manhole cover assembly according to  claim 6 , wherein said further pivot means ( 76 ) connecting the outer end of the hinge arm ( 74 ) to the cover ( 10 ) includes a pivot pin carried by said hinge arm ( 74 ), said pivot pin being slidable in slots ( 78 ) carried by guide members ( 80 ) fixed to the underside of the cover, the arrangement being configured to allow the cover to be opened through substantially 180° of pivoting so that the cover can rest on level ground next to the said frame assembly. 
   
   
       8 . A manhole cover assembly including an upper frame ( 20 ) and a manhole cover ( 10 ), a hinge mechanism ( 16 ) for connecting said cover to one side of said upper frame, and having locking means ( 18 ) for locking the other side of the cover to the upper frame, said hinge mechanism comprising;
 bracket means ( 70 ) fixed to an inner surface of said upper frame and positioned to be covered by the cover when closed, said bracket means supporting a pivot ( 72 );   a hinge arm ( 74 ) having an inner end carried by said pivot;   further pivot means ( 76 ) connecting an outer end of the hinge arm to the underside of the cover;   a downwardly facing cam surface ( 68 A) carried by said upper frame adjacent to said bracket means; and   a locking element ( 82 ) carried by the underside of said cover ( 10 ) and positioned so that, in the closed position of the cover, said locking element fits against the underside of said cam surface and prevents the hinge side of the cover from being raised when the other side of the cover is held closed by said locking means.   
   
   
       9 . A manhole cover assembly according to  claim 8 , wherein said further pivot means ( 76 ) connecting the outer end of the hinge arm to the cover includes a pivot pin ( 76 ) carried by said hinge arm, said pivot pin ( 76 ) being slidable in slots ( 78 ) carried by guide members ( 80 ) fixed to the underside of the cover, the arrangement being configured to allow the cover to be opened through substantially 180° of pivoting so that the cover can rest on level ground next to the said frame assembly. 
   
   
       10 . A manhole cover assembly according to  claim 1 , wherein said upper frame ( 20 ) has an upstanding flange ( 28 ) surrounding a recess for the manhole cover ( 10 ), and said flange has apertures ( 60 ) spaced around its periphery, said apertures being suitable for receiving spikes ( 62 ) which can be driven into the ground surrounding the upper frame to secure the upper frame to the ground. 
   
   
       11 . A manhole cover assembly according to  claim 6  comprising an anti-rotation device ( 94 ) for preventing unlocking of the locking mechanism ( 18 ) as a result of vibration. 
   
   
       12 . A manhole cover assembly according to  claim 11 , wherein the anti-rotation device ( 94 ) acts between the locking element ( 86 , 88 ) and the cover ( 10 ) to prevent relative rotation therebetween. 
   
   
       13 . A manhole cover assembly according to  claim 12 , characterize in that wherein the locking element ( 88 ) has a socket head ( 92 ) having an external flat ( 92 A) and accommodated, in use, within a hole ( 90 ) in the cover ( 10 ) the hole having an internal flat ( 90 B), and the anti-rotation device comprises a cap ( 94 ) adapted to fit between the socket head and the surrounding hole and having internal and external flats ( 94 B, 94 A) for engaging, respectively, the socket head flat and the flat of the hole, to prevent unlocking of the locking member by rotation of the locking element relative to the cover. 
   
   
       14 . A manhole cover assembly according to  claim 13 , wherein the cap ( 94 ) is resilient and sized to engage either or both of the socket head ( 92 ) and the hole ( 90 ) so as to inhibit dislodging of the cap as a result of vibration caused by traffic. 
   
   
       15 . A method for providing an adjustable manhole assembly comprising the steps of:
 providing a generally flat top surface portion of a manhole top section,   placing on said top section a metallic adapter part having a lower, annular surface portion suitable for resting on said flat top surface portion, the adapter having a part-spherical, upwardly convex upper surface,   and placing on said metallic adapter part an adjustable frame assembly having an upper, inner frame movable within a lower, outer frame for adjusting the height of the inner frame, said lower, outer frame having an annular lower surface which mates with the upper part-spherical surface of the adapter.   
   
   
       16 . A manhole cover assembly as claimed in  claim 1 , wherein the adapter part ( 36 ) comprises a lower adapter section ( 36 ′) and an upper adapter section ( 36 ″), the lower adapter section ( 36 ″) providing said lower, annular surface ( 36 A) for resting upon said flat top surface ( 12 A) of the manhole and the upper adapter section ( 36 ′) providing said part-spherical, upwardly convex upper surface ( 36 C), lower and upper surfaces of the upper and lower adapter sections, respectively, being configured to permit adjustment of the angle between the upper adapter section and the lower adapter section so as to adjust the inclination of the part-spherical, upwardly convex upper surface relative to said top surface. 
   
   
       17 . A manhole cover assembly as claimed in  claim 16 , wherein the lower adapter section ( 36 ″) has a part-spherical inner wall diverging upwardly and outwardly, the upper adapter section ( 36 ″) having a lowermost peripheral edge with a diameter such that the upper adapter section rests in and is slidable relatively to the part-spherical inner wall. 
   
   
       18 . A manhole cover assembly as claimed in  claim 16 , wherein the height of the lower adapter section varies from a maximum at one side to a minimum at a diametrically opposite position. 
   
   
       19 . A manhole cover assembly according to  claim 8 , wherein said upper frame ( 20 ) has an upstanding flange ( 28 ) surrounding a recess for the manhole cover ( 10 ), and said flange has apertures ( 60 ) spaced around its periphery, said apertures being suitable for receiving spikes ( 62 ) which can be driven into the ground surrounding the upper frame to secure the upper frame to the ground. 
   
   
       20 . A manhole cover assembly according to  claim 8  comprising an anti-rotation device ( 94 ) for preventing unlocking of the locking mechanism ( 18 ) as a result of vibration.