Patent Publication Number: US-11649604-B2

Title: Height adjustment mechanism for a manhole assembly and manhole assembly comprising the same

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     There is provided a height adjustment mechanism. In particular, there is provided a height adjustment mechanism for a manhole assembly, and a manhole assembly comprising the same. 
     BRIEF SUMMARY OF INVENTION 
     There is provided an improved height adjustment mechanism for a manhole assembly, as well as a manhole assembly comprising the same. 
     According to one aspect, there is provided a height adjustment mechanism for a manhole assembly. The height assembly mechanism includes an annular lower body having a threaded interior bore. The height assembly mechanism includes an annular insert threadably engageable with the lower body. The height assembly mechanism includes an annular upper body threadably engageable with and extending outwards from the lower body. Abutting of the upper body with the insert fixes positioning of the upper body. 
     According to a further aspect, there is provided a height adjustment mechanism for a manhole assembly. The height assembly mechanism includes an annular lower body having a bore and an axis. The lower body includes two or more radially inwardly-extending, axially-spaced-apart height-fixing supports. The height assembly mechanism includes an annular upper body with an annular wall. The upper body has an aperture extending through the wall thereof. The upper body includes at least one protuberance coupled to and extending radially outwards from the wall thereof. The aperture is adjacent to the protuberance. The upper body is axially rotatable from an insertion position in which the upper body is in part insertable within the bore of the lower body, to a fixed position in which the protuberance is abutable with a respective one of the height-fixing supports. The height assembly mechanism includes a locking member selectively insertable via the aperture of the wall. The locking member is configured to inhibit rotation of the upper body relative to the lower body. 
     According to another aspect, there is provided a height adjustment mechanism for a manhole assembly. The height assembly mechanism includes an annular lower body having a bore and an axis. The height assembly mechanism includes two or more radially inwardly-extending, axially-spaced-apart height-fixing supports. The height assembly mechanism includes an annular upper body. The upper body includes at least one protuberance extending radially outwards therefrom. The protuberance has a groove axially-extending therethrough. The upper body is axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body to a fixed position in which the protuberance is abutable with a respective one of the height-fixing supports. The height assembly mechanism includes a locking member insertable within the groove of the protuberance. The locking member is abutable with at least one distal end of at least one of the height-fixing supports. The locking member is configured to inhibit rotation of the upper body relative to the lower body. 
     According to yet a further aspect, there is provided a height adjustment mechanism for a manhole assembly. The height assembly mechanism includes an annular lower body having a bore and an axis. The lower body includes two or more radially inwardly-extending, axially-spaced-apart height-fixing supports. Each of the height-fixing supports has spaced-apart tapered ends. The height assembly mechanism includes an annular upper body. The upper body includes at least one radially outwardly-extending protuberance. The protuberance has spaced-apart tapered ends. The upper body is axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body to a fixed position in which the protuberance is abutable with a respective one of the height-fixing supports. 
     According to yet another aspect, there is provided a height adjustment mechanism for a manhole assembly. The height assembly mechanism includes an annular lower body having a lower end, an upper end spaced-apart from the lower end, an axis and a bore. The axis and the bore extend from the lower end to the upper end of the lower body. The lower body includes a plurality of axially spaced-apart, height-fixing support assemblies. The height assembly mechanism includes an annular upper body having a lower end and an upper end spaced-apart from the lower end of the upper body. The upper body includes a plurality of circumferentially spaced-apart, radially outwardly-extending flange members. The flange members are adjacent to the lower end of the upper body. The upper body is axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body to a fixed position in which at least one of the flange members is abutable with a respective one of the height-fixing support assemblies. 
     According to an even further aspect, there is provided a height adjustment mechanism for a manhole assembly. The height assembly mechanism includes an annular lower body having a bore. The lower body includes an annular wall extending about the bore. The height assembly mechanism includes an annular upper body. The upper body includes an annular wall and is shaped to selectively fit partially within the bore of the lower body. The wall of a first of the lower body and the upper body includes a plurality of circumferentially spaced-apart recessed receptacles of varying depths. The wall of a second of the lower body and the upper body includes at least one protrusion extending radially outwards therefrom. The protrusion is shaped to at least partially fit within respective ones of the receptacles. 
     There is also provided a manhole assembly including any one of the above set out the height adjustment mechanisms. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be more readily understood from the following description of preferred embodiments thereof given, by way of example only, with reference to the accompanying drawings, in which: 
         FIG.  1    is a top, front, exploded perspective view of a manhole assembly according to a first aspect, the assembly including an annular lower body, an annular upper body and an annular insert therebetween; 
         FIG.  2    is a front, exploded perspective view thereof; 
         FIG.  3    is a side elevation of the assembly of  FIG.  2   , with the insert disposed within and threadably coupled to the lower body, with the upper body threadably engaged with the lower body and being shown in an intermediate height position, and a spacer ring of the assembly further being shown and a manhole barrel of the assembly also being shown in fragment; 
         FIG.  4    is a sectional elevation view taken along lines  4 - 4  of the assembly shown in  FIG.  3   ; 
         FIG.  5    is a side elevation view of the assembly of  FIG.  3   , with the insert disposed within and threadably coupled to the lower body, with the upper body shown in solid lines in a retracted position fully threadably engaged with the lower body, and with the upper body shown in stippled lines in an extended position and partially threadably engaged with the lower body; 
         FIG.  6    is a top, front, exploded perspective view of a manhole assembly according to a second aspect, the assembly including an annular lower body comprising a plurality of circumferentially spaced-apart, axially spaced-apart and radially inwardly-extending flange members aligned in columns, and the assembly including an annular upper body with a plurality of circumferentially spaced-apart, radially outwardly-extending flange members shaped to selectively engage with the flange members of the lower body; 
         FIG.  7    is a top, front, exploded perspective view thereof; 
         FIG.  8    is a side elevation view of the assembly of  FIG.  7   , with the upper body partially received by the lower body and being shown in an intermediate height position, and a spacer ring of the assembly further being shown and a manhole barrel of the assembly also being shown in fragment; 
         FIG.  9    is a sectional elevation view taken along lines  9 - 9  of the assembly shown in  FIG.  8   ; 
         FIG.  10    is an enlarged interior perspective view, shown in fragment, of a locking member of the manhole assembly extending through an aperture of the annular wall of the upper body of manhole assembly, with the locking member engaging with flange members of the lower body of the manhole assembly and inhibiting rotation of the upper body relative to the lower body; 
         FIG.  11    is a side elevation view of the assembly of  FIG.  8   , with the upper body shown in solid lines in a retracted position fully disposed within the lower body, and with the upper body shown in stippled lines in an extended position partially disposed within the lower body; 
         FIG.  12    is a top, front, exploded perspective view of a manhole assembly according to a third aspect, the assembly including an annular lower body comprising a plurality of circumferentially spaced-apart, axially spaced-apart and radially inwardly-extending flange members aligned in a segmented spiral formation, and the assembly including an annular upper body with a plurality of circumferentially spaced-apart, radially outwardly-extending flange members shaped to selectively engage with the flange members of the lower body; 
         FIG.  13    is a front, exploded perspective view thereof; 
         FIG.  14    is a side elevation of the assembly of  FIG.  13   , with the upper body partially received by the lower body and being shown in an intermediate height position, and a spacer ring of the assembly further shown and a manhole barrel of the assembly also being shown in fragment; 
         FIG.  15    is a sectional elevation view taken along lines  15 - 15  of the assembly shown in  FIG.  14   ; 
         FIG.  16    is a side elevation view of the assembly of  FIG.  14   , with the upper body shown in solid lines in a retracted position fully disposed within the lower body, and with the upper body shown in stippled lines in an extended position partially disposed within the lower body; 
         FIG.  17    is a top, front, exploded perspective view of a manhole assembly according to a fourth aspect, the assembly including an annular lower body comprising a plurality of circumferentially spaced-apart receptacles of varying depths, and an annular upper body including a plurality of circumferentially spaced-apart, radially outwardly-extending protrusions shaped to selectively engage with various ones of the receptacles of the lower body; 
         FIG.  18    is a front, exploded perspective view thereof; 
         FIG.  19    is a side elevation of the assembly of  FIG.  17   , with the upper body partially received by the lower body and being shown in an intermediate height position, and a spacer ring of the assembly further being shown and a manhole barrel of the assembly also being shown in fragment; 
         FIG.  20    is a sectional elevation view taken along lines  20 - 20  of the assembly shown in  FIG.  19   ; 
         FIG.  21    is a side elevation view of the assembly of  FIG.  19   , with the upper body shown in solid lines in a retracted position fully disposed within the lower body, and with the upper body shown in stippled lines in an extended position partially disposed within the lower body; 
         FIG.  22    is top, side perspective view of an annular upper body of a manhole assembly according to a fifth aspect, the annular upper body including a plurality of circumferentially spaced-apart, radially outwardly-extending protrusions; 
         FIG.  23    is a sectional view in fragment taken along lines  23 - 23  of the annular upper body of the manhole assembly of  FIG.  22   ; 
         FIG.  24    is a bottom, side perspective view of the annular upper body of the manhole assembly of  FIG.  22   ; 
         FIG.  25    is a top, side perspective view of an annular lower body of the manhole assembly according to the fifth aspect, the annular lower body comprising a plurality of circumferentially spaced-apart receptacles of varying depths shaped to selectively engage with various ones of the receptacles of the lower body of  FIG.  22   ; 
         FIG.  26    is a bottom, side perspective view of the lower body of  FIG.  25   ; 
         FIG.  27    is a top plan view thereof; and 
         FIG.  28    is a bottom plan view thereof. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings and first to  FIG.  3   , there is shown a manhole assembly  40 . 
     The manhole assembly includes a manhole barrel  42  partially shown in fragment. The manhole barrel has a top  44 . The manhole assembly  40  includes an annular spacer, in this example a concrete spacer ring  46 . The spacer ring has a bottom  48  which abuts the top  44  of the manhole barrel  42 . The spacer ring has a top  50  spaced-apart from the bottom thereof. Manhole barrels and spacer rings per se, including their various parts and functionings, are well known to those skilled in the art and thus will not be described in further detail. 
     As seen in  FIG.  1   , the manhole assembly  40  includes a height adjustment mechanism  52 . The height adjustment mechanism includes an annular lower body  54 . The lower body has a lower end  56  and an upper end  58  spaced-apart from the lower end. As seen in  FIG.  2   , the lower body  54  has an annular wall  60  which extends from the lower end to the upper end thereof. The wall has an exterior surface  61  and the lower body has an exterior  62  aligned with the exterior surface. The lower body  54  has an interior surface, in this example a threaded interior surface  64 . The lower body has a longitudinal, central axis  66  about which the wall  60  extends. 
     As seen in  FIG.  3   , lower body  54  has an annular flange  68  coupled to and extending radially outwards from wall  60  at the lower end  56  of the lower body. The flange abuts and extends along the top  50  of spacer ring  46 . As seen in  FIG.  1   , a plurality of circumferentially spaced-apart apertures  70  extend through the flange  68 . The apertures are shaped to receive fasteners, in this example bolts (not shown) for coupling the flange to the spacer ring  46  seen in  FIG.  3   . Referring back to  FIG.  1   , the lower body  54  includes a plurality of circumferentially spaced-apart stiffener members, in this example triangular stiffener plates  72  which extend between and couple together the flange  68  and wall  60 . 
     As seen in  FIG.  2   , lower body  54  has a bore  74  about which annular wall  60  extends. The threaded interior surface  64  of the lower body and the bore are in communication with each other. The threaded interior surface  64  extends from the lower end  56  to the upper end  58  of the lower body  54 . 
     Referring to  FIG.  1   , the height adjustment mechanism  52  includes an annular insert, in this example a lock ring  76 . The lock ring has a lower end  78  and an upper end  80  spaced-apart from its lower end. The lock ring  76  includes a threaded exterior surface  82 . As seen in  FIG.  4   , the lock ring is insertable within the lower body  54  via bore  74  and the threaded exterior surface of the lock ring is configured to threadably engage with the threaded interior surface  64  of the lower body. 
     As seen in  FIG.  2   , the lock ring  76  includes an interior wall  84  opposite the threaded exterior surface  82  thereof. The lock ring includes a plurality of circumferentially spaced-apart, radially inwardly-extending protrusions, in this example four evenly spaced-apart protrusions  86 ,  88 ,  90  and  92 . The protrusions are generally rectangular prisms in shape in this example and extend from the lower end  78  to the upper end  80  of the lock ring  76  in this example. 
     Referring to  FIG.  1   , the height adjustment mechanism  52  includes an annular upper body  94 . The upper body has a lower end  96  and an upper end  98  spaced-apart from the lower end. As seen in  FIG.  4   , the lower end of the upper body is shaped to abut the upper end  80  of the lock ring  76 . 
     Referring back to  FIG.  1   , the upper body  94  has an annular wall  100  extending from the lower end  96  to the upper end  98  thereof. The annular wall has a lower interior surface  102 . The lower interior surface of the wall  100  extends from the lower end  96  towards the upper end  98  of the upper body  94 . The upper body includes a plurality of circumferentially spaced-apart protrusions which couple to and extend radially inwards relative to the lower interior surface  102  of the wall. In this example, there are four, evenly spaced-apart protrusions, as shown by way protrusions  104  and  105  in  FIG.  1    and protrusions  106  and  107  in  FIG.  4   . Each protrusion has a rounded bottom, in this example an outwardly convex-facing bottom, as seen by bottom  101  for protrusion  104  in  FIG.  2   . 
     Referring to  FIG.  4   , the upper body  94  has an annular lip  108  which extends radially inwards relative to the wall  100 . The annular lip is positioned between the lower end  96  and the upper end  98  of the upper body, and is positioned above and adjacent to the protrusions as shown by protrusions  106  and  107  in this example. The annular lip  108  is shaped receive a manhole cover (not shown). 
     Referring back to  FIG.  2   , the upper body  94  includes a radially outwardly-extending flange  110  which extends radially outwards from the wall  100  of the upper body. The flange is adjacent to the upper end  98  of the upper body. As seen in  FIG.  1   , annular lip  108  extends radially inwards relative to the flange  110 . 
     Still referring to  FIG.  1   , the wall  100  of the upper body  94  has a lower exterior surface, in this example a lower threaded exterior surface  112 . As seen in  FIG.  4   , the upper body  94  is shaped to selectively fit partially within the bore  74  of the lower body  54  and threadably engage with interior surface  64  of the lower body  54 . The exterior surface  82  of the lock ring  76  is likewise insertable within bore  74  and threadably engageable with the interior surface of the lower body. The upper body  94  thus extends outwards and upwards from the lower body  54  in part. Abutting of the upper body with the lock ring  76  fixes positioning of the upper body relative to the lower body. 
     Referring to  FIG.  2   , each of the protrusions  86 ,  88 ,  90  and  92  of the lock ring  76  and protrusions  104  of the upper body  94  is shaped to receive a tangentially-directed force which promotes rotation of the lock ring and upper body, respectively. In this example and as seen in  FIG.  1   , the protrusions are shaped to receive impacts  114  from a hammer  116 , with the impacts promoting rotation of the lock ring  76  and the upper body  94  relative to the lower body  54 . In this manner and referring to  FIG.  4   , positioning of the lock ring relative to the lower body may first be adjusted to a desired height or distance of separation Ds relative to the lower end  56  of the lower body by rotating the lock ring relative to the lower body  54 . Rotation of the lock ring  76  in a first direction, in this example a clockwise direction as shown by arrow of numeral  121 , causes the lock ring to lower downwards relative to the lower body and from the perspective of  FIG.  4   . Rotation of the lock ring in a second direction, in this example a counter-clockwise direction as shown by arrow of numeral  123 , causes the lock ring to raise upwards relative to the lower body  54  and from the perspective of  FIG.  4   . 
     Upon the desired height or distance of separation Ds being met, the upper body  94  is threadably positioned in place by rotating the upper body  94  in the clockwise direction relative to the lower body such that the lower end  96  of the upper body abuts with the upper end  80  of the lock ring  76  to fix positioning of the upper body relative to the lower body  54  in place. 
     As seen in  FIG.  5   , the manhole assembly  40  has a retracted position shown in solid lines. The lock ring  76  seen in  FIG.  4    is near to the lower end  56  of the lower body  54  and the upper body  94  abuts the lock ring when the manhole assembly is in the retracted position. The manhole assembly  40  is moveable from the retracted position to an extended position shown in stippled lines in  FIG.  5   . 
     The upper body  94  abuts the lock ring  76  seen in  FIG.  4   . The lock ring is positioned adjacent to the upper end  58  of the lower body  54  when the manhole assembly is in the extended position. In this manner and referring to  FIG.  5   , the height adjustment mechanism  52  enables the height H, or extent to which the upper body  94  extends above the lower body  54 , to be selectively adjustable as desired. The manhole assembly  40  may thus be installed such that flange  110  of the upper body  94  generally aligns flush with the surface of a road (not shown), for example. In this embodiment, the height H may be equal to four or five inches. However, this is not strictly required and the extent of height adjustment may be larger or small in other examples. 
     Height adjustment mechanism  52  may comprise a high-strength means for adjusting the extent to which the upper body  94  extends upwards from the lower body  54  that enables infinite micro-adjustment. Lock ring  76 , in addition to functioning as a locking means, may further function to reduce clearance between the upper body  94  and lower body  54  which may otherwise permit rocking of the upper body relative to the lower body. 
       FIGS.  6  to  11    show a manhole assembly  40 . 1  and height adjustment mechanism  52 . 1  therefor according to a second aspect. Like parts have like numbers and functionings as the manhole assembly  40  and height adjustment mechanism  52  shown in  FIGS.  1  to  5    with the addition of decimal extension “0.1”. Manhole assembly  40 . 1  and height adjustment mechanism  52 . 1  are the same as described for manhole assembly  40  and height adjustment mechanism  52  shown in  FIGS.  1  to  5    with the following exceptions. 
     Referring to  FIG.  6   , lower body  54 . 1  of the manhole assembly  40 . 1  includes a plurality of radially inwardly-extending columns of height-fixing supports, in this example three evenly spaced-apart arrangements, in this case vertically-extending columns  118 ,  120  and  122 , of height-fixing flange members. Each of the flange members is inwardly concave with one side aligned with interior surface  64 . 1  of the lower body  54 . 1 . 
     Each column comprises a plurality of axially spaced-apart height-fixing flange members, as seen in  FIG.  7    by: flange members  124 ,  126 ,  128 ,  130 ,  132  and  134  for column  118 ; flange members  136 ,  138 ,  140 ,  142 ,  144  and  146  for column  120 ; and a similar number of flange members for column  122  only flange member  148  of which is shown in  FIG.  7   . 
     Flange members  124 ,  136  and  148  align horizontally with each other in a first plane P 1  seen in  FIG.  9   . As seen in  FIG.  9   : flange members  126  and  138  align horizontally with each other in a second plane P 2 ; flange members  128  and  140  align horizontally with each other in a third plane P 3 ; flange members  130  and  142  align horizontally with each other in a fourth plane P 4 ; flange members  132  and  144  align horizontally with each other in a fifth plane P 5 ; and flange members  134  and  146  align horizontally with each other in a sixth plane P 6 . Each of the flange members is generally in the shape of an arc-shaped rectangular prism with spaced-apart tapered ends, as seen in  FIG.  6    by tapered ends  150  and  152  for flange member  140 . 
     Still referring to  FIG.  6   , the lower body  54 . 1  of the manhole assembly  40 . 1  has a plurality of recessed regions, in this example three evenly spaced-apart recessed regions  149 ,  151  and  153  that extend from the lower end  56 . 1  to the upper end  58 . 1  of the lower body. Recessed region  149  is between the columns  118  and  120  of flange members. Recessed region  151  is between the columns  120  and  122  of flange members. Recessed region  153  is between the columns  122  and  118  of flange members. 
     The upper body  94 . 1  of the manhole assembly  40 . 1  includes a plurality of circumferentially spaced-apart and axially-extending, vertical strengthening ribs, as shown by way of example by ribs  154 ,  156 ,  158 ,  160 ,  162 ,  164 , and  166 . The ribs couple in this example via welding to and extend radially inwards from the interior surface  102 . 1  of annular wall  100 . 1  of the upper body. Each of the ribs  154 ,  156 ,  158 ,  160 ,  162 ,  164 , and  166  is generally an isosceles trapezoid in lateral cross-section in this example. Annular wall  100 . 1  is continuous and extends from upper end  98 . 1  of the upper body  94 . 1  towards lower end  96 . 1  of the upper body. 
     A plurality of circumferentially spaced-apart apertures, in this example three apertures, as seen by apertures  168  and  170  in  FIG.  6    and aperture  169  in  FIG.  8   , extend through the annular wall  100 . 1  of the upper body  94 . 1 . The apertures are rectangular in shape with rounded corners in this example and are shaped to be sufficiently large so as to receive one&#39;s hand therethrough. 
     As seen in  FIG.  7   , the upper body  94 . 1  of the manhole assembly  40 . 1  includes a plurality of circumferentially spaced-apart protuberances, in this example end flange members  172 ,  174  and  176 . The flange members of the upper body are coupled to and extend radially outwards from the exterior surface  112 . 1  of wall  100 . 1 . Each of the flange members  172 ,  174  and  176  of the upper body  94 . 1  is outwardly convex with one side aligned with the exterior  177  of the upper body. The flange members are adjacent to and align with the lower end  96 . 1  of the upper body in this example. The flange members  172 ,  174  and  176  of the upper body  94 . 1  are generally arc-shaped rectangular prisms in shape in this example. Each flange member of the upper body has spaced-apart tapered ends in this example, as seen by tapered ends  178  and  180  for flange member  176  in  FIG.  6   . The apertures  170  of the wall  100 . 1  are adjacent to the ends  178  of respective ones of the flange members  176  of the upper body  94 . 1  in this example. 
     Referring to  FIG.  7   , the flange members  172 ,  174  and  176  of the upper body are shaped to selectively pass through respective ones of the recessed regions  149 ,  151  and  153  of the lower body  54 . 1  in an insertion position of the upper body. The height or distance of separation of the upper body  94 . 1  relative to the flange  68 . 1  and lower end  56 . 1  of the lower body  54 . 1  may be adjusted and selected as desired in the insertion position. Upon the desired height being obtained, the upper body is then axially rotated relative to the lower body from the insertion position to a fixed position in which, as seen in  FIG.  9   , the flange members  176  of the upper body  94 . 1  abut with respective one of the flange members of the lower body  54 . 1  which are aligned in a given plane. This is shown in  FIG.  9    by the flange members  176  of the upper body abutting the tops  143  of flange members  142  of the lower body aligned in fourth plane P 4 . The flange members of the upper body are thus shaped to be received between adjacent pairs of flange members  140  and  142  within a given column  120 . In this example and referring to  FIG.  6   , rotation of the upper body  94 . 1  relative to the lower body  54 . 1  by α degrees, in this case 60 degrees in a clockwise direction  181  or counter-clockwise direction  183 , enables the manhole assembly  40 . 1  to move from an insertion position to a fixed position. However, this is not strictly required and there may be other arrangements and columns of flange members and recessed regions in other examples. 
     Referring to  FIG.  7   , each flange member has a groove axially-extending therethrough, as seen by groove  182  extending through flange member  176 . The grooves are positioned adjacent to ends  178  of the flange members in this example. As seen in  FIG.  10   , manhole assembly  40 . 1  includes a locking member, in this example of an L-shaped locking pin  184 . The locking pin is selectively insertable at least in part through one of the apertures  168  of wall  100 . 1  of the upper body  94 . 1 . The locking pin  184  includes a first portion  186  shaped to be received within groove  182  and which in this example is vertically-extending when in use. The locking pin includes a second portion  188  coupled to and extending perpendicular to the first portion and which in this example is horizontally-extending when in use. The second portion of the locking pin  184  is shaped to extend through aperture  168  and abut a lower peripheral edge  190  of wall  100 . 1  which is in communication with the aperture in this example. The first portion  186  of the locking pin is abutable with one or more ends  152  of the flange members  130  of the lower body  54 . 1 . Inadvertent or undesired rotation of the upper body  94 . 1  of the manhole assembly  40 . 1  relative to the lower body  54 . 1  of the manhole assembly causes the second portion  188  of the locking pin  184  to abut a respective one of the side peripheral edge portions  191  and  193  of wall  100 . 1  which are in communication with aperture  168 . The side peripheral edge portions  191  and  193  extend upwards from the lower peripheral edge  190  of the wall, and the lower peripheral edge of the wall extends between said side peripheral edge portions. The locking pin  184  so shaped is thus configured to inhibit rotation of the upper body  94 . 1  relative to the lower body  54 . 1  upon the upper body  94 . 1  being rotated into the fixed position seen in  FIG.  10   . 
     In this example, the flange members of the lower body  54 . 1  are arranged such that the upper body  94 . 1  may be positioned in one of five positions vertically relative to the lower body  94 . 1 , with each of the positions being axially spaced-apart by a set incremental distance D I  seen in  FIG.  10   . In this embodiment the distance D I  equals to approximately 1.25 inches. In this manner and referring to  FIG.  11   , the height H. 1 , or extent to which the upper body  94 . 1  extends above the lower body  54 . 1 , is selectively adjustable as desired. In this example (H. 1 ) divided by 5 equals to D I . However, neither five positions per se nor the distance of 1.25 inches between positions is strictly required and the distance between flange members of the lower body, as well as the number of axially-spaced-apart flange members of the lower body, may be different in other examples. 
       FIGS.  12  to  16    show a manhole assembly  40 . 2  and height adjustment mechanism  52 . 2  therefor according to a third aspect. Like parts have like numbers and functionings as the manhole assembly  40 . 1  and height adjustment mechanism  52 . 1  shown in  FIGS.  6  to  11    with decimal extension “0.2” replacing decimal extension “0.1” and being added for parts not previously have decimal extensions. Manhole assembly  40 . 2  and height adjustment mechanism  52 . 2  are the same as described for manhole assembly  40 . 1  and height adjustment mechanism  52 . 1  shown in  FIGS.  6  to  11    with the following exceptions. 
     As seen in  FIG.  13   , upper body  94 . 2  of the manhole assembly  40 . 2  includes a plurality of circumferentially spaced-apart stops, in this example three knobs positioned adjacent to respective ones of the flange members of the upper body. This is shown in  FIG.  13    by knobs  192  and  194  positioned adjacent to and above flange members  174 . 2  and  176 . 2 . Each knob is generally a rectangular pyramid in shape in this example with a proximal end  196  coupled to the lower exterior surface  112 . 2  of wall  100 . 2 , a distal end  198  spaced-apart outwardly from the proximal end, a top  200  which extends and tapers from the proximal end to the distal end, and a bottom  202  which extends and tapers from the proximal end to the distal end. Each knob  194  has a pair of spaced-apart sides  204  and  206  which extend from the top and bottom thereof. The sides of the knob also extend and taper from the proximal end  196  to the distal end  198  of the knob. The top  200 , bottom  202  and sides  204  and  206  are generally triangular in this example. Each knob is positioned between the ends of its associated flange member, as seen in  FIG.  12    by knob  194  positioned between  178 . 2  and  180 . 2  of flange member  176 . 2 . 
     Referring to  FIG.  13   , lower body  54 . 2  of the manhole assembly  40 . 2  includes a plurality of radially inwardly-extending columns of height-fixing supports, in this example three evenly spaced-apart segmented spiral arrangements  118 . 2 ,  120 . 2  and  122 . 2  of height-fixing flange members. Adjacent ones of the flange members of the height-fixing support assemblies are arranged in a segmented spiral formation, as seen by segmented spiral formation  118 . 2  comprising adjacent flange members  124 . 2 ,  126 . 2 ,  128 . 2 ,  130 . 2 , and  132 . 2 . In this example, the flange members extend about central axis  66 . 2  of the lower body  54 . 2  of the manhole assembly  40 . 2  and flange member  124 . 2  is offset by or angularly spaced-apart by a set angle relative to flange member  126 . 2  in this case 30 degrees, which in turn is offset by flange member  128 . 2  by 30 degrees, which in turn is offset by flange member  130 . 2  by 30 degrees, which in turn is offset by flange member  130 . 2  by 30 degrees. However, this is not strictly required, and the flange members in a given formation may be offset from each other by a different angular amount in other examples. 
     Recessed regions  149 . 2 ,  151 . 2  and  153 . 2  extend from the lower end  56 . 2  to the upper end  58 . 2  of the lower body  54 . 2  and also extend in a segmented spiral formation. As seen in  FIG.  13   , recessed region  149 . 2  is between segmented spiral formations  118 . 2  and  120 . 2  of flange members. Recessed region  151 . 2  is between the columns  120 . 2  and  122 . 2  of flange members. Recessed region  153 . 2  is between the columns  122 . 2  and  118 . 2  of flange members. 
     In operation and referring to  FIG.  12   , lowering upper body  94 . 2  onto lower body  54 . 2  causes flange members  172 . 2 ,  174 . 2  and  176 . 2  of the upper body to abut flange members  148 . 2 ,  136 . 2  and  124 . 2  aligned in the first plane P 1 . 2  seen in  FIG.  15    of the lower body. Referring back to  FIG.  13   , rotation of the upper body relative to the lower body in a first rotational direction, in this example a counter-clockwise direction as shown by arrow of numeral  208 , enables the upper body to incrementally lower into and be received by the lower body until the flange members of the upper body abut the flange members  126 . 2  of the lower body in the next plane down, in this example the second plane P 2 . 2  seen in  FIG.  15   . 
     Knobs  192  and  194  are positioned and shaped such that rotation of the upper body  94 . 2  in a second rotational direction opposite the first rotational direction, in this example in a clockwise direction as shown by arrow of numeral  210 , causes the sides  204  of the knobs  194  to abut the ends  150 . 2  of the flange members  124 . 2  of the lower body  54 . 2  in the plane P 1 . 2  above the plane P 2 . 2  on which the flange members of the upper body are abutting, with said planes being shown in  FIG.  15   . The knobs thus function to enable rotation of the upper body  94 . 2  relative to the lower body  54 . 2  in a first rotational direction and inhibit rotation of the upper body relative to the lower body in a second rotational direction which is opposite the first rotational direction. 
     In this manner, the upper body of the manhole assembly  40 . 2  may continue to be incrementally rotated in a counter-clockwise direction and be thereafter lowered to the flange members of the lower body in the next plane lower down until the desired height H. 2  or degree of extension of the upper body relative to the lower body seen in  FIG.  16    is achieved. The upper body  94 . 2  may be removed from the lower body  54 . 2  by following the above steps in reverse. 
       FIGS.  17  to  21    show a manhole assembly  40 . 3  and height adjustment mechanism  52 . 3  therefor according to a fourth aspect. Like parts have like numbers and functionings as the manhole assembly  40 . 1  and height adjustment mechanism  52 . 1  shown in  FIGS.  6  to  11    with decimal extension “0.3” replacing decimal extension “0.1” and being added for parts not previously having decimal extensions. Manhole assembly  40 . 3  and height adjustment mechanism  52 . 3  are the same as described for manhole assembly  40 . 1  and height adjustment mechanism  52 . 1  shown in  FIGS.  6  to  11    with the following exceptions. 
     As seen in  FIG.  18   , the upper body  94 . 3  of the manhole assembly  40 . 3  includes an annular portion  211  adjacent to the upper end  98 . 3  thereof. The annular portion of the upper body extends outwards from wall  100 . 3  and is between the wall and flange  110 . 3  in this example. 
     The wall of one of the lower body and the upper body of the manhole assembly  40 . 3 , in this example the wall  100 . 3  of upper body  94 . 3  includes a plurality of circumferentially spaced-apart, radially outwardly-extending protrusions: in this case three evenly spaced-apart protrusions as shown by protrusions  213  and  215  in  FIG.  17    and as shown by protrusion  217  in  FIG.  19   . Each of the protrusions couples to and extends radially outwards from wall  100 . 3  and couples to and extends downwards from flange  110 . 3  in this example. Each of the protrusions is generally a rectangular prism in shape in this example. 
     As seen in  FIG.  18   , another one of the lower body and the upper body of the manhole assembly  40 . 3 , in this example lower body  54 . 3  includes a plurality of sets of circumferentially spaced-apart, recessed receptacles of varying depths: in this case three sets  212 ,  214  and  216  of seven receptacles, with each being formed from the wall  60 . 3  of the lower body in this example. The receptacles are shaped to selectively receive respective ones of the protrusions  213  and  215 . Set  212  includes receptacles  218 ,  220 ,  222 ,  224 ,  226 ,  228  and  230  of increasing depth in the vertical direction, with respective successive ones of the receptacles extending increasingly downwards from the upper end  58 . 3  towards the lower end  56 . 3  of the lower body  54 . 3 . Set  214  includes receptacles  232 ,  234 ,  236 ,  238 ,  240 ,  242 , and  244  of increasing depth in the vertical direction, with respective successive ones of the receptacles extending increasingly downwards from the upper end towards the lower end of the lower body  54 . 3 . Set  216  includes receptacles  246 ,  248 ,  250 ,  252 ,  254 ,  256  and  258  of increasing depth in the vertical direction, with respective successive ones of the receptacles extending increasing downwards from the upper end  58 . 3  towards the lower end  56 . 3  of the lower body  54 . 3 . 
     As seen in  FIG.  17   , each of the receptacles is generally rectangular in shape in this example and extends radially outwards from interior surface  102 . 3  of wall  60 . 3  of the lower body  54 . 3  towards exterior surface  61 . 3  of the wall. The wall of the lower body includes a plurality of circumferentially spaced-apart elongate divider portions between adjacent receptacles, with divider portions extending downwards from the upper end  58 . 3  of the lower body towards the lower end  56 . 3  of the lower body. This is seen in  FIG.  18    by divider portion  260  between receptacles  222  and  224 , and divider portion  261  between receptacles  220  and  222 . Each of the divider portions is L-shaped in side profile in this example, with each said divider portion  260  including a ledge  223 . The ledges of divider portions collectively form an annularly-arranged seat shaped to receive annular portion  211  of upper body  94 . 3 . 
     Still referring to  FIG.  18   , the lower body  54 . 3  of the manhole assembly  40 . 3  includes a plurality of circumferentially spaced-apart, radially and axially-extending pairs of walls which function to define respective ones of the receptacles in this example. This is shown by walls  225  and  227  between receptacle  258 . The walls  225  and  227  extend from the interior surface  64 . 3  towards the exterior  62 . 3  of the lower body  54 . 4 . 
     As seen in  FIG.  18   , the sets  212 ,  214  and  216  of receptacles include shallow receptacles  218 ,  232 , and  246 , respectively, as best seen by shallow receptacle  218  for set  212 . The shallow receptacles extend downwards from the upper end  58 . 3  of the lower body  54 . 3  to the same extent and to the least extent relative to the other receptacles. The sets  212 ,  214  and  216  of receptacles include deep receptacles  230 ,  244  and  258 , as best seen by deep receptacle  258  for set  216 . The deep receptacles extend downwards from the upper end  58 . 3  of the lower body  54 . 3  to the same extent and to the greatest extent relative to the other receptacles. Deep receptacles  230 ,  244  and  258  are adjacent to shallow receptacles  232 ,  246  and  218 , respectively, in this example. 
     Receptacles  220 ,  234  and  248  extend downwards from the upper end  58 . 3  of the lower body  54 . 3  to the same extent and are shaped to be incrementally deeper than shallow receptacles  218 ,  232  and  246 . Receptacles  222 ,  236  and  250  extend downwards from the upper end of the lower body to the same extent and are shaped to be incrementally deeper than receptacles  220 ,  234  and  248 . Receptacles  224 ,  238  and  252  extend downwards from the upper end  58 . 3  of the lower body  54 . 3  to the same extent and are shaped to be incrementally deeper than receptacles  222 ,  236  and  250 . Receptacles  226 ,  240  and  254  extend downwards from the upper end of the lower body to the same extent and are shaped to be incrementally deeper than shallow receptacles  224 ,  238  and  252 . Receptacles  228 ,  242  and  256  extend downwards from the upper end  58 . 3  of the lower body  54 . 3  to the same extent and are shaped to be incrementally deeper than receptacles  226 ,  240  and  254 . Deep receptacles  230 ,  244  and  258  are shaped to be incrementally deeper than receptacles  228 ,  242  and  256 . 
     In operation and referring to  FIG.  18   , the upper body  94 . 3  of the manhole assembly  40 . 3  may be rotated and lowered onto lower body  54 . 3  such that protrusions  213  and  215  of the upper body align with and are received by the shallow receptacles  218 ,  232  and  246  of the lower body. This configuration is the most extended position of height adjustment mechanism  52 . 3  in which the upper body extends outwards from the lower body to the maximum extent. Raising up and then rotating the upper body  94 . 3  relative to the lower body  54 . 3  in a first rotational direction, in this example a counter-clockwise direction as shown by arrow of numeral  208 . 3 , enables the protrusions  213  and  215  of the upper body to be lowered into and be received by the incrementally deeper receptacles  220 ,  234  and  248  of the lower body. This causes the upper body to be incrementally lowered and incrementally extended upwards relative to the lower body to a lesser degree. In this manner, the upper body  94 . 3  can be selectively positioned/lowered relative to the lower body  54 . 3  until a desired height of the manhole assembly  40 . 3  is achieved. The positioning of the protrusions  213  and  215  of the upper body  94 . 3  into the deep receptacles  230 ,  244  and  258  coincides with the height adjustment mechanism  52 . 3  being in its retracted position. 
     Height adjustment mechanism  52 . 3  of manhole assembly  40 . 3  may result in a strong and secure multi-height positioning solution that still enables the various parts thereof to be cast without cores. The need for machining may further be inhibited by manhole assembly  40 . 3 . Height adjustment mechanism  52 . 3  may also provide a greater degree of fine adjustment, with the difference in depth DD seen in  FIG.  17    between adjacent receptacles within a set being in the order of 0.75 inches in this example. However, this is not strictly required, and this incremental value, as well as the number of receptacles and/or protrusions of the upper body, may vary in other examples. 
       FIGS.  22  to  28    show a manhole assembly  40 . 4  and height adjustment mechanism  52 . 4  therefor according to a fifth aspect. Like parts have like numbers and functionings as the manhole assembly  40 . 3  and height adjustment mechanism  52 . 3  shown in  FIGS.  17  to  21    with decimal extension “0.4” replacing decimal extension “0.3” and being added for parts not previously having decimal extensions. Manhole assembly  40 . 4  and height adjustment mechanism  52 . 4  are the same as described for manhole assembly  40 . 3  and height adjustment mechanism  52 . 3  shown in  FIGS.  17  to  21    with the following exceptions. 
     As seen in  FIG.  22   , the protrusions  213 . 4 ,  215 . 4  and  217 . 4  of the upper body  94 . 4  of the manhole assembly  40 . 4  are tapered in this embodiment. In this example, each of the protrusions tapers from the upper end  98 . 4  of the body to the lower end  96 . 4  of the body. The protrusions are generally trapezoidal prisms in shape in this example. 
     As seen in  FIG.  23   , the upper body  94 . 4  of the manhole assembly  40 . 4  includes an annular protrusion in the form of a seat  262  which is adjacent to, which is below and which extends radially inwards relative to annular lip  108 . 4  in this embodiment. The seat is trapezoidal in cross-section in this example, with a slopped, inwardly-facing and top-facing upper annular edge portion  264  and a slopped, inwardly-facing and bottom-facing lower annular edge portion  266 . 
     As seen in  FIG.  25   , the receptacles  218 . 4 ,  220 . 4 ,  222 . 4 ,  224 . 4 ,  226 . 4 ,  228 . 4 ,  230 . 4 ,  232 . 4 ,  234 . 4 ,  236 . 4 ,  238 . 4 ,  240 . 4 ,  242 . 4 ,  244 . 4 ,  246 . 4 ,  248 . 4 ,  250 . 4 ,  252 . 4 ,  254 . 4 ,  256 . 4  and  258 . 4  of the lower body  52 . 4  of the manhole assembly  40 . 4  are tapered, generally trapezoidal in shape, and shaped to fit the protrusions  213 . 4 ,  215 . 4  and  217 . 4  of the upper body  52 . 4  seen in  FIG.  22   . Referring back to  FIG.  25   , the plurality of circumferentially spaced-apart, radially and axially extending pairs of walls  225 . 4  and  227 . 4  for respective ones of the receptacles of the lower body  52 . 4  are tapered in this embodiment, tapering as the walls extend downwards from the upper end  58 . 4  towards the lower end  56 . 4  of the lower body  54 . 4 . 
     Referring to  FIG.  26   , the lower body of the manhole assembly  40 . 4  includes a plurality of circumferentially spaced-apart, downwardly-extending positioning members  268 ,  270  and  272 . The members are in communication with bore  74 . 4 . As seen in  FIGS.  27  and  28   , each of the positioning members  268 ,  270  and  272  is arcuate-shaped in top and bottom profile in this example. As seen with reference to  FIG.  26   , each of the positioning members is L-shaped in side cross-section. The positioning members  268 ,  270  and  272  are shaped to abut with corresponding annular surfaces of a concrete spacer ring, such as ring  46 . 2  seen in  FIG.  14    for manhole assembly  40 . 2 . In this manner, the positioning members  268 ,  270  and  272  may function to retain positioning of the lower body  52 . 2  of the manhole assembly  40 . 4  relative to the spacer ring. 
     As seen in  FIG.  28   , the lower body of the manhole assembly includes a plurality of circumferentially spaced-apart, arcuate-shaped recesses  274 ,  276  and  278  interposed between positioning members  268 ,  270  and  272 , respectively. The recesses align below the shallower receptacles, as seen in  FIG.  25    by recess  276  positioned below receptacles  230 . 4 ,  232 . 4  and  236 . 6  of the lower body  52 . 4 . 
     ADDITIONAL DESCRIPTION 
     Examples of manhole assemblies and height adjustment mechanisms thereof have been described. The following clauses are offered as further description.
         1. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a threaded interior bore; an annular insert threadably engageable with the lower body; and an annular upper body threadably engageable with and extending outwards from the lower body, whereby abutting of the upper body with the insert fixes positioning of the upper body relative to the lower body.   2. The height adjustment mechanism as clause in clause 1, wherein the lower body has a lower end and an upper end spaced-apart from the lower end thereof, and wherein the manhole assembly is moveable from a retracted position to an extended position, the insert being positioned adjacent to the lower end of the lower body when the manhole assembly is in the retracted position, and the insert being positioned near the upper end of the lower body when the manhole assembly is in the extended position.   3. The height adjustment mechanism as clause in any one of clauses 1 to 2, wherein the insert includes at least one radially inwardly-extending protrusion.   4. The height adjustment mechanism as clause in clause 3 wherein the insert has an upper end and an lower end, and wherein the protrusion extends between said upper end and said lower end of the insert.   5. The height adjustment mechanism as clause in any one of clauses 3 and 4, wherein the protrusion is a rectangular prism in shape.   6. The height adjustment mechanism as clause in any one of clauses 1 to 5, wherein the upper body includes at least one radially inwardly-extending protrusion.   7. The height adjustment mechanism as clause in clause 6, wherein the protrusion of the upper body has an outwardly convex facing bottom.   8. The height adjustment mechanism as clause in any one of clauses 1 to 2, wherein both the insert and the upper body include a plurality of circumferentially spaced-apart, radially inwardly-extending protrusions.   9. The height adjustment mechanism as clause in clause 8 wherein each of the insert and the upper body includes four, evenly spaced-apart ones of said protrusions.   10. The height adjustment mechanism as clause in any one of clauses 8 to 9, wherein the protrusions are shaped to receive a tangentially-directed force, said force promoting rotation of the insert and the upper body, respectively.   11. The height adjustment mechanism as clause in any one of clauses 8 to 10, wherein the protrusions are shaped to receive impacts from a hammer, said impacts promoting rotating of the insert and the upper body, respectively.   12. The height adjustment mechanism as clause in any one of clauses 1 to 11, wherein the upper body has a lower end abutting the insert, has an upper end spaced-apart from the lower end thereof, includes a radially outwardly-extending flange adjacent to the upper end thereof, and includes an annular lip positioned between the lower end and the upper end thereof, the annular lip extending radially inwards relative to the flange.   13. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a threaded interior bore; an annular upper body threadably engageable with and extending outwards from the lower body, the annular upper body including a plurality of circumferentially spaced-apart, radially inwardly-extending protrusions.   14. The height adjustment mechanism as clause in clause 13, wherein the protrusions are shaped to receive a tangentially-directed force, said force promoting rotation of the upper body relative to the lower body.   15. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a bore; and an annular upper body being shaped to selectively fit partially within the bore of the lower body, a first of the lower body and the upper body including a plurality of circumferentially spaced-apart recessed receptacles of varying depths and a second of the lower body and the upper body including at least one protrusion extending outwards therefrom, the protrusion being shaped to at least partially fit within respective ones of said receptacles.   16. The height adjustment mechanism as clause in clause 15 wherein the annular lower body includes an annular wall extending about the bore thereof, wherein the annular upper body includes an annular wall, wherein the wall of the first of the lower body and the upper body includes said plurality of circumferentially spaced-apart recessed receptacles of varying depths and wherein the wall of the second the lower body and the upper body includes said at least one protrusion extending radially outwards therefrom.   17. The height adjustment mechanism as clause in any one of clauses 15 and 16, wherein the protrusion is generally a rectangular prism in shape.   18. The height adjustment mechanism as clause in any one of clauses 15 to 17, wherein the receptacles are generally rectangular prisms in shape.   19. The height adjustment mechanism as clause in any one of clauses 15 and 16, wherein the protrusion is generally a trapezoidal prism in shape.   20. The height adjustment mechanism as clause in any one of clauses 15, 16 and 19, wherein the receptacles are generally trapezoidal prisms in shape.   21. The height adjustment mechanism as clause in any one of clauses 15 and 16, wherein the receptacles are tapered and wherein the at least one protrusion is tapered.   22. The height adjustment mechanism as clause in any one of clauses 15 to 21, wherein the receptacles include a set of three circumferentially spaced-apart shallow receptacles, a set of three circumferentially spaced-apart deep receptacles, and at least one set of three circumferentially spaced-apart receptacles of a depth between the shallow receptacles and the deep receptacles.   23. The height adjustment mechanism as clause in clause 22, wherein the lower body has an upper end and a lower end, wherein each of the receptacles has a bottom, wherein the bottoms of the shallow receptacles are near the upper end of the lower body and wherein the bottoms of the deep receptacles are near the lower end of the lower body.   24. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a bore; and an annular upper body being shaped to selectively fit partially within the bore of the lower body, a first of the lower body and the upper body including a plurality of pairs of walls and a second of the lower body and the upper body including at least one protrusion extending outwards therefrom, the protrusion being shaped to at least partially fit within and abut respective ones of said pairs of walls.   25. The height adjustment mechanism as clause in clause 24 wherein the at least one protrusion is tapered and wherein the pairs of walls are tapered.   26. The height adjustment mechanism as clause in any one of clauses 24 to 25, wherein the at least one protrusion is generally a trapezoidal prism in shape.   27. The height adjustment mechanism as clause in any one of clauses 15 to 26, wherein the lower body includes a plurality of circumferentially spaced-apart, arcuate-shaped, downwardly-extending positioning members.   28. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a bore, having an axis and including two or more radially inwardly-extending, axially-spaced-apart height-fixing supports; an annular upper body including an annular wall, having an aperture extending through said wall, and including at least one protuberance coupled to and extending radially outwards from the wall, the aperture being adjacent to said protuberance, the upper body being axially rotatable from an insertion position in which the upper body is in part insertable within the bore of the lower body, to a fixed position in which the protuberance is abutable with a respective one of said height-fixing supports; and a locking member selectively insertable via the aperture of the wall, the locking member being configured to inhibit rotation of the upper body relative to the lower body.   29. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a bore, having an axis and including two or more radially inwardly-extending, axially-spaced-apart height-fixing supports; an annular upper body including at least one protuberance extending radially outwards therefrom, the protuberance having a groove axially-extending therethrough, the upper body being axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body to a fixed position in which the protuberance is abutable with a respective one of said height-fixing supports; and a locking member insertable within said groove of the protuberance and is abutable with at least one distal end of at least one of said height-fixing supports, the locking member being configured to inhibit rotation of the upper body relative to the lower body.   30. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a bore, having an axis and including two or more radially inwardly-extending, axially-spaced-apart height-fixing supports, each of the height-fixing supports having spaced-apart tapered ends; and an annular upper body including at least one radially outwardly-extending protuberance, the protuberance having spaced-apart tapered ends, the upper body being axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body, to a fixed position in which the protuberance is abutable with a respective one of said height-fixing supports.   31. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a lower end, an upper end spaced-apart from the lower end, an axis and a bore, the axis and the bore of the annular lower body extending from the lower end to the upper end of the annular lower body, and the annular lower body including a plurality of axially spaced-apart, height-fixing support assemblies; and an annular upper body having a lower end, having an upper end spaced-apart from the lower end of the upper body, and including a plurality of circumferentially spaced-apart, radially outwardly-extending flange members, the flange members being adjacent to the lower end of the upper body, the upper body being axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body to a fixed position in which at least one of the flange members is abutable with a respective one of said height-fixing support assemblies.   32. The height adjustment mechanism as clause in clause 31, wherein each of the height-fixing support assemblies comprises a plurality of circumferentially spaced-apart flange members.   33. The height adjustment mechanism as clause in any one of clauses 31 to 32, wherein adjacent ones of the flange members of the height-fixing support assemblies are aligned in a column.   34. The height adjustment mechanism as clause in any one of clauses 31 to 32, wherein adjacent ones of the flange members of the height-fixing support assemblies are arranged in a segmented spiral formation.   35. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a bore, having an axis and including two or more radially-inwardly extending, axially-spaced-apart height-fixing supports; an annular upper body including an annular wall, having an aperture extending through said wall, and including at least one protuberance coupled to and extending radially-outwards from the wall, the aperture being adjacent to said protuberance, the upper body being axially rotatable from an insertion position in which the upper body is in part insertable within the bore of the lower body to a fixed position in which the protuberance is abutable with a respective one of said height-fixing supports; and a locking member selectively insertable via the aperture of the wall, the locking member being configured to inhibit rotation of the upper body relative to the lower body.   36. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a bore, having an axis and including two or more radially-inwardly extending, axially-spaced-apart height-fixing supports; an annular upper body including at least one protuberance extending radially-outwards therefrom, the protuberance having a groove axially-extending therethrough, the upper body being axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body to a fixed position in which the protuberance is abutable with a respective one of said height-fixing supports; and a locking member insertable within said groove of the protuberance and is abutable with at least one distal end of at least one of said height-fixing supports, the locking member being configured to inhibit rotation of the upper body relative to the lower body.   37. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a bore, having an axis and including two or more radially-inwardly extending, axially-spaced-apart height-fixing supports, each of the height-fixing supports having spaced-apart tapered ends; and an annular upper body including at least one radially-outwardly extending protuberance, the protuberance having spaced-apart tapered ends, the upper body being axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body to a fixed position in which the protuberance is abutable with a respective one of said height-fixing supports.   38. A height adjustment mechanism for a manhole assembly, the height assembly mechanism comprising: an annular lower body having a lower end, an upper end spaced-apart from the lower end, an axis and a bore, the axis and the bore of the annular lower body extending from the lower end to the upper end of the annular lower body, and the annular lower body including a plurality of axially spaced-apart, height-fixing support assemblies; and an annular upper body having a lower end, having an upper end spaced-apart from the lower end of the upper body, and including a plurality of circumferentially spaced-apart, radially-outwardly extending flange members, the flange members being adjacent to the lower end of the upper body, the upper body being axially rotatable from an insertion position in which the upper body is insertable in part within the bore of the lower body to a fixed position in which at least one of the flange members is abutable with a respective one of said height-fixing support assemblies.   39. The height adjustment mechanism as set out in clause 38, wherein each of the height-fixing support assemblies comprises a plurality of circumferentially spaced-apart flange members.   40. The height adjustment mechanism as set out in any one of clauses 38 and 39, wherein adjacent ones of the flange members of the height-fixing support assemblies are aligned in a column.   41. The height adjustment mechanism as set out in any one of clauses 38 and 39 wherein adjacent ones of the flange members of the height-fixing support assemblies are arranged in a segmented spiral formation.   42. A manhole assembly comprising the height adjustment mechanism as clause in any one of clauses 1 to 41.       

     It will be appreciated that many variations are possible within the scope of the invention described herein. It will be understood by someone skilled in the art that many of the details provided above are by way of example only and are not intended to limit the scope of the invention which is to be determined with reference to at least the following claims.