U.S. patent application number 12/302855 was filed with the patent office on 2009-10-01 for adjustable manhole cover assembly.
Invention is credited to Ismail Cemil Suatac.
Application Number | 20090241435 12/302855 |
Document ID | / |
Family ID | 38778065 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090241435 |
Kind Code |
A1 |
Suatac; Ismail Cemil |
October 1, 2009 |
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 (36C) of a
metallic adapter (36), which in turn rests on the generally flat
surface (12A) 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.
Inventors: |
Suatac; Ismail Cemil;
(Ottawa, CA) |
Correspondence
Address: |
ADAMS PATENT & TRADEMARK AGENCY
P.O. BOX 11100, STATION H
OTTAWA
ON
K2H 7T8
CA
|
Family ID: |
38778065 |
Appl. No.: |
12/302855 |
Filed: |
May 30, 2007 |
PCT Filed: |
May 30, 2007 |
PCT NO: |
PCT/CA2007/000950 |
371 Date: |
November 28, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60808966 |
May 30, 2006 |
|
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Current U.S.
Class: |
52/19 ;
52/745.16 |
Current CPC
Class: |
E02D 19/14 20130101 |
Class at
Publication: |
52/19 ;
52/745.16 |
International
Class: |
E02D 29/14 20060101
E02D029/14 |
Claims
1. An adjustable manhole cover assembly comprising; an adapter part
(36) having a lower, annular surface portion (36A) suitable for
resting on a generally flat top surface (12A) of a manhole top
section (12), the adapter part having a part-spherical, upwardly
convex metal upper surface (36C), 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 (22B)
which forms a mating surface slidable on the upper part-spherical
surface (36C) 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 (22B) has a slope similar to that part-spherical
surface (36C) of the adapter part (36).
3. A manhole cover assembly according to claim 1, wherein the
upper, inner frame (20) has an upper portion (20A) and a lower
portion (20B) with respective mating surfaces, and at least one of
these surfaces is part-spherical, whereby the upper portion (20A)
of the upper, inner frame (20) may be adjusted in slope relative to
the lower portion (20B) 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
(42B) 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 (68A) 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 (68A) 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.degree. 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 (68A)
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.degree. 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 (92A) and accommodated, in use, within a hole (90)
in the cover (10) the hole having an internal flat (90B), 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 (94B,94A) 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 (36A) for resting upon said
flat top surface (12A) of the manhole and the upper adapter section
(36') providing said part-spherical, upwardly convex upper surface
(36C), 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.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from U.S. Provisional
patent application No. 60/808,966 filed May 30, 2006, the contents
of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a manhole cover assembly
for mounting a manhole cover above a manhole basin and is
especially applicable to manhole assemblies which allow adjustment
of the slope of the manhole cover, and usually also its height, as
necessitated by resurfacing a road surface and/or by frost-heave of
the surrounding ground.
BACKGROUND ART
[0003] Manhole basins, which may be a sewer basin having an inlet
and an outlet, or may be a catchment basin having only an inlet,
are normally cast of concrete. A frame of metal is fixed to the top
of the concrete basin and holds the manhole cover. In order to keep
the cover level with a road or ground surface, it is frequently
necessary to alter the height between the manhole cover and the top
of the basin, particularly in regions where there is much frost
heave; adjustment to the height is usually done when a road is
resurfaced. Adjustment of slope may also be necessary, as when the
camber of a road is changed. In addition, adjustment of the lateral
position may be necessary, especially with catchment basins where
the manhole must be positioned accurately close to a curb.
[0004] Various constructions of adjustable manhole frames have been
proposed to deal with height adjustment and to avoid replacing
concrete parts. In some cases, screw jacks have been used between
the annular frame which holds the cover and the top of the concrete
manhole basin. In other cases, an outer ring, supported by the
basin, has internal helical threads of large diameter within which
is an inner ring having mating screw threads, and which is
rotatable to adjust its height. Examples of patents showing such
arrangements are listed in my U.S. Pat. Nos. 6,179,518, issued Jan.
30, 2001, and 6,698,973, issued Mar. 2, 2004.
[0005] Many of the prior patents are concerned with height
adjustment, and show little or no provision for slope adjustment.
Most of the patents show upper and lower parts of the frame
assembly to be connected by helical threads surrounding the annular
upper portion of the frame so that rotation of this upper portion
changes its height without any change to its slope. However, some
other patents show jack-type screw adjusters which are spaced
around the frame and which can be adjusted individually to alter
the slope, as well as the height, of the upper frame portion. Such
arrangements are shown in the following patents:
[0006] U.S. Pat. No. 3,930,739, which issued Jan. 6, 1976 to
Larsson et al.;
[0007] U.S. Pat. No. 4,149,816, which issued Apr. 17, 1979 to Piso;
and
[0008] U.S. Pat. No. 4,925,337, which issued May 15, 1990 to Spiess
et al.
[0009] These prior arrangements would appear to have some
drawbacks. In particular, they seem to offer only limited slope
adjustment. This is especially true of Piso, where more than slight
change of slope would seemingly cause binding in the adjusting
screws. In Larsson et al. and Spiess et al., the amount of slope
adjustment would be limited by binding between outer edges of the
upper frame portion and the fixed surrounding structure. Also,
these prior patents do not show any seals which would prevent
ingress of soil or other material into the mechanical parts if
there were to be significant slope adjustment. Larsson et al. and
Piso show small seals which would accommodate only a small amount
of slope adjustment, while Spiess et al. show no seal at all.
[0010] My aforesaid U.S. Pat. No. 6,698,973 shows an improvement in
the prior designs that provides both height adjustment and slope
adjustment of the cover frame. In the arrangement shown in that
patent, a manhole basin of precast concrete has a top section with
a convex part-spherical top which is engaged by a concave
part-spherical outer lower frame part of the metallic frame
assembly. The frame assembly includes an inner, upper frame part
connected to the outer, lower frame part by screw threads. This
upper frame part itself has upper and lower portions joined by
part-spherical mating surfaces. The two pairs of part-spherical
mating surfaces allow the inclination of the outer, lower frame
part, and of the inner, upper frame part to be independently
adjusted, so that both the inclination and the lateral position of
the inner upper ring part can be varied. The height of the upper
frame part is also adjusted by the conventional, helical screw
threads.
[0011] While the invention of my U.S. Pat. No. 6,698,973 has been
valuable, nevertheless it has the limitation that it envisions the
use of a specially-shaped precast concrete manhole top section with
the part-spherical top, or the use of a relatively heavy concrete
adapter. I have found that there is a need for a device which can
be used when it is not convenient to replace a conventional
pre-cast top section with one similar to that of my U.S. Pat. No.
6,698,973.
DISCLOSURE OF INVENTION
[0012] The present invention seeks to overcome, or at least
ameliorate, one or more of the disadvantages of these known
arrangements, or at least provide an alternative.
[0013] In accordance with one aspect of the present invention, an
adjustable manhole assembly comprises:
[0014] an adapter part having a lower, annular surface portion
suitable for resting on a generally flat top surface portion of a
manhole top section, the adapter having a part-spherical, upwardly
convex metal upper surface,
[0015] and an adjustable frame assembly having an upper, inner
frame movable within a lower, outer frame for adjusting the height
of the inner frame, and wherein the lower, outer frame has an
annular lower surface which mates with the upper part-spherical
surface of the adapter.
[0016] Preferably, both of the mating surfaces are part spherical,
or at least have similar sloping surfaces. Also, the mating
surfaces are preferably surrounded by a sealing collar to minimize
entry of soil or other matter between these surfaces.
[0017] While the assembly shown in my prior U.S. Pat. No. 6,698,973
was made of cast grey iron, the castings used in embodiments of the
present invention preferably are of ductile iron. This allows the
components to be thinner and stronger, this can reduce the weight
by about one halt making the assembly more attractive to users.
[0018] As in my aforesaid U.S. Pat. No. 6,698,973, the upper, inner
frame has an upper portion and a lower portion with mating
surfaces, and at least one of these surfaces is part spherical, so
that the upper portion of the inner frame may be adjusted in slope
relative to the lower portion of the inner frame while maintaining
a sealing relationship between the mating surfaces. Again, both of
these upper mating surfaces are preferably part-spherical. The
inner and outer frames have the conventional screw-threaded
engagement which allow for height adjustment.
[0019] The lower mating surfaces between the manhole basin adapter
section and the frame assembly provide a coarse slope adjustment,
while the upper mating surfaces between the upper and lower
portions of the upper, inner frame provide a fine slope
adjustment.
[0020] In my U.S. Pat. No. 6,698,973, the outer surface of the
outer frame part has a concrete collar which contacts a sealing
collar, this sealing collar allows the outer frame to rise while
still maintaining at least a partial seal between the outer frame
and the part-spherical surface on which it rests. This seal is
improved with the present construction, since here there is no
concrete collar, but instead at least a lower portion of the outer
frame has a machined metal surface, and the sealing collar has a
resilient O-ring in contact with this metal surface, and so
maintains a good seal during its movement relative to the outer
frame.
[0021] The adapter part comprise a lower adapter section and an
upper adapter section, the lower adapter section providing said
lower, annular surface for resting upon said flat top surface of
the manhole and the upper adapter section providing said
part-spherical, upwardly convex upper surface, 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.
[0022] The lower adapter section may have a part-spherical inner
diverging upwardly and outwardly and the upper adapter section have
a lowermost peripheral edge with a diameter such that the
circumferential lower edge of the upper adapter section rests in
and is slidable relatively to the part-spherical inner wall to
permit tilting of the upper adapter section relative to the lower
adapter section.
[0023] A manhole assembly embodying the first aspect of the
invention may be used in a process to adapt existing manholes to
accommodate differing cambers of roads. Thus, in accordance with
another aspect of the present invention, a method for providing an
adjustable manhole assembly comprises the steps of:
[0024] providing a generally flat top surface portion of a manhole
top section,
[0025] placing on said top section an 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 metal upper surface,
[0026] 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.
[0027] Embodiments of the invention may also employ a special hinge
with a locking arrangement for locking the manhole cover in place
on the frame assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] A preferred embodiment of the invention will now be
described by way of example with reference to the accompanying
drawings, in which;
[0029] FIG. 1 is a top view of a manhole cover, a man hole cover
frame assembly and an adapter;
[0030] FIG. 2A is a sectional elevation of the upper part of a
manhole basin having the adjustable manhole cover frame assembly
and adapter mounted on a manhole basin top section, with the cover
closed;
[0031] FIG. 2B is an enlarged view of a portion of FIG. 2A showing
a hinge;
[0032] FIG. 2C is an enlarged view of a portion of FIG. 2A showing
a locking mechanism;
[0033] FIG. 2D is a detail cross-sectional view of the locking
mechanism modified by inclusion of an anti-vibration cap for the
head of a shaft of the locking mechanism;
[0034] FIG. 2E is a perspective view of a shaft of a locking
element;
[0035] FIG. 2F is a perspective view of the cap adapted to fit the
head of the locking element shaft;
[0036] FIG. 2G is a detail cross-sectional view taken on line G-G
of FIG. 2D;
[0037] FIG. 3 is an exploded view of components of the frame
assembly, and including the adapter;
[0038] FIG. 4 is an enlarged view of the adapter and portions of
the frame assembly, showing the slip joint between the lower, outer
frame and the adapter;
[0039] FIG. 5A is an enlarged view of a top portion of the frame
assembly showing the joint between the upper and lower portions of
the upper, inner frame;
[0040] FIG. 5B is a view of parts similar to those of FIG. 5A but
taken at a different circumferential position around the frame
assembly;
[0041] FIG. 6 is a detail view of the hinge between the manhole
cover and the upper, inner frame, with the cover open;
[0042] FIG. 7 is a view of the underside of the manhole cover
assembly with the cover closed;
[0043] FIG. 8A is a side view of a modified adapter part having a
lower adapter section supporting an upper adapter section in a
level position;
[0044] FIG. 8B is a side view of the modified adapter part
supporting the upper adapter section at a maximum tilt angle
relative to the manhole top section;
[0045] FIG. 8C is a perspective view of the upper adapter
section;
[0046] FIG. 8D is a plan view of the lower adapter section; and
[0047] FIG. 8E is a perspective view of the lower adapter
section.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
[0048] FIGS. 1 and 2 show a manhole cover 10 supported on the top
section 12 of a manhole basin by a manhole cover frame assembly 14
which is adjustable. The manhole basin, of which the top precast
section 12 is shown partially in FIG. 1, is cast of concrete, and
rests on middle and lower sections which are not shown. The frame
assembly 14 allows adjustment of the height and slope of the cover
10 relative to the ground level G. The cover is connected to the
frame assembly 14 on one side by a hinge indicated at 16, and, when
closed, is connected to the other side of the frame assembly 14 by
a locking mechanism indicated at 18; details of the hinge and
locking mechanism are given below.
[0049] The frame assembly 14, in common with some prior art
designs, has two parts formed of cast metal, firstly an upper,
inner frame part 20, and secondly a lower, outer frame part 22. The
upper frame 20 has an external helical screw thread 24 which
engages an internal screw thread 26 of the lower frame 22. The
upper frame screw thread 24 subtends just one complete 360.degree.
circle. Rotation of the upper frame relative to the normally
stationary lower frame adjusts its height in accordance with prior
art procedures; for example, as disclosed in my U.S. Pat. No.
6,698,973, to which the reader is directed for reference and which
is incorporated herein by reference. The rotation can be done by
conventional methods, for example by use of a special tool having
depending spigots which fit into bores in the top of the upper
frame 20.
[0050] The upper, inner frame 20 has an inwardly projecting flange
28 and an upstanding, surrounding flange 30, which flanges provide
a recess for receiving the edge portion of the manhole cover 10.
The underside of the outer edge portion of the cover 10 has a
groove 32 which receives a sealing gasket 34 (FIG. 2A).
[0051] The top precast section 12 has an annular flat top 12A. On
this rests a generally flat, annular lower surface 36A of an
adapter 36, which is a hollow, ductile iron casting having a
circular central aperture 36B slightly smaller in diameter than the
interior of upper inner frame 20, and an outer surface 36C which is
of convex, part-spherical form. The part-spherical surface 36C has
a center of curvature below the spatial center of the manhole top
section 12. On this surface 36C rests the lower rim 22A of lower,
outer frame 22, such lower rim having an outwardly diverging
surface having a slope similar to the slope of the surface 36C.
[0052] As best seen in FIG. 4, the mating surfaces are surrounded
by a sealing collar 38 having a cylindrical part 38A lying against
the outside of outer frame 22 and a flared skirt part 38B lying
against the part-spherical upper surface 36C. This sealing collar
38 may be made of glass fiber reinforced polyester, and preferably
includes upper and lower internal annular recesses which
accommodate, respectively, O-rings 42A and 42B which contact the
outer surface of outer frame 22 and the upper surface 36C of the
adapter 36. The recesses holding the O-rings have openings which
are narrower than the width of the unstressed O-rings so that the
O-rings do not fall out. This collar 38 is intended to largely
prevent soil or other dirt from entering between the mating
surfaces, especially when frost lifts the outer frame 22, and also
prevents infiltration of ground water when the water table is high.
The ground which has been back-filled on top of the lower part 38B
of the collar 38 prevents this rising if the outer frame 22 rises
with frost, with the lower part of the outer frame sliding against
the O-ring 42A. To allow this motion, the lowermost few inches of
the outer frame 22 are machined to a smooth surface. The rising and
falling of the outer frame part can prevent potholes usually caused
by frost heave or ground movement, and consequently reduces the
cracking asphalt and reduces the need for road repairs.
[0053] Referring to FIGS. 5A and 5B, the upper, inner frame 20
itself is formed of upper and lower portions 20A and 20B, which are
also joined by part-spherical mating surfaces. These surfaces
include a concave surface 44B in lower portion 20B, and a convex
surface 44A on the underside of upper ring portion 20A. Each of
these surfaces has a center of curvature above the center of the
manhole cover 10, Details of the joint are shown in FIGS. 5A, 5B
and 6, which show enlarged views of the mating parts. As shown, the
upper frame flange 28 is effectively split to provide these part
spherical mating surfaces 44A and 44B.
[0054] As shown in FIG. 5B, the upper part 28A of this flange,
which is integral with the upper frame portion 20A, has a series of
countersunk bores 46 for receiving the heads of screws 48. The
arrangement is similar to that described in my aforesaid U.S. Pat.
No. 6,698,973, and which is shown in detail in FIGS. 2A and 2B of
that patent. However, one difference here is that the lower
portions of bores 46 diverge downwards so that the screws 48 can
remain vertical when the adjustments are made. The screws 48 pass
through enlarged apertures 46A in the lower part of the flange 28B
which is integral with the lower frame portion 20B, the screws then
passing through washers 50 and being secured by nuts 52. The
washers 50 are elliptical, being elongated in the circumferential
direction so that they can engage the flange 28B at two opposed
sides of the apertures 46A, while allowing the screws to come close
to the radial outer side of the apertures. These large apertures
46A for the screws 48 allow radial movement of the screws 48 when
they have been loosened to allow adjustment of the upper frame
portion 20A on the lower frame portion 20B between the co-axial
position shown in FIG. 5A and an eccentric position. Since
diverging bores 46 allow the screws 48 to remain vertical, there is
no need for an extra washer to accommodate misalignment. However,
since the alignment of screws 48 needs to change with respect to
the flange 28A, the lower surfaces of the screw heads 48A, and the
corresponding upper face of the enlarged portion of the countersunk
bore 46, have complementary convex and concave surfaces.
[0055] In order to exclude dirt and asphalt from between the outer
frame 22 and the inner frame 20, inner and outer cylindrical
sealing collars 54A and 54B are provided surrounding the outer top
flange 30 of the upper portion 20A of inner frame 20. The sealing
collars 54A and 54B, rest on the top of upper flange 54A projecting
both outwardly and inwardly from the top of lower, outer frame 22.
These collars 54A,54B may be of medium density 5 mm thick
polyethylene. The collars are resilient enough to accommodate the
movement of the upper frame portion 20A relative to the lower frame
portion 20B. The movement of the upper frame portion 20A will
usually be limited to about 3.degree. or 0.5 cm; the greater
movement occurs between the mating surfaces 34B and 36C.
[0056] During re-surfacing of the road for height adjustment, the
inner cylindrical sealing collar 54A will be removed from its
housing, after taking out the upper ring portion 20A with its
flange 28A; then the inner frame 20 becomes easily rotatable for
height adjustment. The outer cylindrical sealing collar 54B remains
fixed, because it sticks to the asphalt. The collars 54A and 54B
prevent dirt and asphalt entering the threads between the outer and
inner frames.
[0057] The outer portions of flange 56A engage the ground, and can
cause the outer frame 22 to remain stationary relative to the upper
layer of ground during frost heave, so that the assembly is partly
self-adjusting to changes in ground level. Under the outer portions
of flange 56A are two triangular projections 58B and 58C, arranged
on opposite sides of the outer frame about 180.degree. apart, and
which are formed with the outer frame during casting. These are
termed "frost wings" and serve to engage the ground and resist
rotation of the outer frame 22.
[0058] A "Teflon".TM. paint or equivalent lubricant may be used
between the upper mating surfaces of the portions 20A and 20B, as
well as around the screw threads 24 and 26, to make for easier
sliding, both when adjusting the slope and when rotating the inner
frame 20 to adjust the height.
[0059] FIGS. 2C and 5A show other mean for securing the inner frame
20 relative to the ground. In particular, the outer top flange 30
has apertures 60 spaced around its periphery, and these receive
spikes 62 which are driven radially outwardly through the two
layers of the plastic collars 54 and into the surrounding
asphalt/ground.
[0060] As shown in FIG. 4, a dirt-excluding plastic barrier skirt
64 is suspended from a fiber ring 66 which hangs from an inner land
68 formed at the bottom of the upper, inner, frame 20. This skirt
64 tends to exclude dirt from the sliding surfaces forming the
joint between the lower rim of lower frame 22 and the adapter
36.
[0061] The hinge 16 shown in FIGS. 2A, 2B, 6 and 7 has a novel
configuration in that it comprises internal hinge which, unlike
some prior art hinges for manhole covers, is not exposed to road
dirt.
[0062] As shown in FIGS. 2B, 6 and 7, hinge 16 includes a spaced
pair of brackets 70 fixed to the inner surface of lower flange 28,
these brackets supporting ends of a pivot pin 72, the central
portion of which carries an angled hinge arm 74, movable between
the brackets. This hinge arm has an inner portion 74A with its
inner end pivoted to bracket 70, and which slopes downwardly from
this pivot pin 72 when the cover 10 is closed, and an outer portion
74B extending from portion 74A at an obtuse angle so as to slope
upwardly in the cover closed situation. As shown in FIGS. 2A, 2B
and 7, the outer end of portion 74B carries a cross pin 76
protruding from its sides, end portions of the cross pin 74 being
slidingly received in slots 78 of parallel guide members 80
extending along, and fixed to, the lower surface of the cover 10.
This combination provides a loose fitting type of hinge which
allows the cover to find its proper sealing position when closed,
without need to carefully align the hinge parts. The bent nature of
the hinge arm 74 allows this to avoid interference with the flange
30 when the cover 10 has been pivoted through 180.degree. from the
closed position into the fully open position shown in FIG. 6; the
180.degree. of movement allowing the cover 10 to lie on ground
adjacent to the manhole, where there is no danger of it
falling.
[0063] Normally, a loose fitting hinge as so far described would
allow the hinged end of the cover 10 to be opened a small amount,
even if the other end of the cover 10 were locked to the underlying
frame as by lock 18. Nowadays, with the prospect of terrorists
inserting explosives or other material into manholes, it is most
desirable that it should not be possible to raise the hinge end of
the cover to any appreciable extent. Accordingly, the ends of the
guide members 80 closest to the edge of the cover 10 are provided
with locking elements 82 which project away from the lower surface
of the cover 10, this being the uppermost surface when the cover 10
is fully open, as in FIG. 6. These locking elements 82 have camming
surfaces 82A facing the effective hinge axis formed by pivot pin
72, and these camming surfaces are designed to cooperate with
inwardly and downwardly sloping undersurfaces 70A of the pivot
brackets 70 so that, when the cover 10 is closed as in FIGS. 2A, 2B
and 7, the surfaces 70A and 82A are close to each other or in
contact, and prevent the cover 10 from being lifted at its hinge
side.
[0064] The locking mechanism 18 is shown in detail in FIG. 2C and,
with a slight modification, in FIG. 2D; this is similar to that
used in my aforesaid '973 patent, but somewhat simplified as to the
form of flange 28A. As shown, the upper frame portion 20A has its
flange 28A provided with a recess 84 in its inner surface, the
recess providing an upper recessed undersurface 84A. This recess 84
accommodates a D shaped locking element or pawl 86 so that the pawl
86 engages the undersurface 84A to prevent opening of the cover 10.
The pawl 84 is carried by a vertical shaft 88 which is rotatably
held in a vertical bore 90 (FIG. 2D) near the outer edge of the
cover 10. The top of the shaft 88 has a non-circular head 92 for
receiving a key for rotating the shaft 88 and for locking or
unlocking the cover 10. As can be seen from FIG. 2D, the head 92
takes the form of a socket having an external flat 92A and a
pentagonal socket 92B with a central pin 92C.
[0065] The uppermost portion of the vertical bore 90 opens into a
generally cylindrical bore extension portion 90A which accommodates
the head 92 and a surrounding resilient cap 94, conveniently of
synthetic plastics material. As shown in FIG. 2F, the bore
extension portion 90A has a flat 92B which engages a corresponding
flat 94A on the exterior of the cap 94 and the interior of the cap
94 has a flat 94B which engages the flat 92A on the exterior of the
socket head 92. The cap 94 is resilient and is sized to grip the
socket head 92 and the interior of bore extension 90A so that it is
not dislodged by vibration caused by traffic. The flats 92A, 94B,
94A and 90B cooperate to prevent rotation of the locking shaft 88
and locking element 86 and consequent unlocking of the mechanism 18
as a result of such vibration.
[0066] Whereas FIG. 2A shows the locking pawl 86 secured to the
shaft 88 by a nut, in FIGS. 2D and 2E the shaft 88 is shown with a
square end 88A which receives the locking pawl 86 and has a
transverse hole 96 to receive a split pin to secure the locking
pawl 86 to the shaft 88.
[0067] As can be seen from FIG. 2D, the depth of the bore extension
90A is sufficient to ensure that the top of cap 94, when fully
inserted, is lower than the surface of cover 10. Also, the recess
84 is spaced well below the seal between the cover 10 and the
flange 28, and so there is no interference between the lock and the
seal.
[0068] It will be appreciated that additional, similar locking
mechanisms 18 could be provided, spaced apart around the edge of
the cover 10.
[0069] In use, the mating surfaces 24B and 36C between the adapter
34 and the frame assembly 14 may be used to allow the frame
assembly to be orientated so that its cylindrical axis is vertical
even if the concrete parts, after back filling, are found to be
tilted. The upper mating surfaces, between the upper frame portions
20A and 20B, are usually adjusted at a later stage, after
resurfacing of a road has occurred, if it is found that slope
adjustment is needed. This involves loosening screws 48, moving the
upper portion 20A so that screws 48 slide along the apertures 46
and then tightening the screws. The upper, inner frame part 20 can
also be rotated as needed to bring the manhole cover up to the road
level.
[0070] While the manhole frame assembly described with reference to
FIGS. 1 to 7 will provide sufficient inclination adjustment for
most applications, even more inclination adjustment may be obtained
by employing an adapter part comprising a pair of adjustable
elements allowing the tilt angle between the uppermost of the pair
of elements and the concrete 12 to be adjusted.
[0071] Thus, referring to FIG. 8A to 8E, the adapter part comprises
two sections, namely an upper adapter section 36' similar to that
shown in FIGS. 1 to 7, and a lower adapter section 36''. The lower
adapter section 36'' comprises an annular part-spherical metal
dish-like element interposed between the upper adapter section 36'
and the top surface 12A of the concrete top section 12 of the
manhole. The central hole of the lower adapter section 36'' is
substantially equal to the inner diameter of the top section 12.
The height of the lower adapter section 36'' varies uniformly
between a maximum and a diametrically opposite minimum. The maximum
height is approximately double the minimum height.
[0072] The diameter of the lower edge of the upper adapter section
36' is slightly less than the horizontal diameter of the lower
adapter section 36'' at its minimum height, so that, when level,
the upper adapter section 36' rests inside the lower adapter
section 36B with its lowermost edge in contact with the
part-spherical surface along a line just below the minimum height
position. As shown in FIG. 8B, the upper adapter section 36' can be
tilted until its lowermost edge contacts the lower adapter section
36'' along a line between the maximum height at one side and the
minimum height at the opposite side.
[0073] Tilting of the upper adapter section 36' relative to the
lower adapter section 36'' is in addition to the tilting of the
outer frame 22 relative to the upper adapter section 36'.
Consequently, the two-piece adapter part 36'/36'' allows the outer
frame 22 to be tilted relative to the top surface 12A by as much as
24-30 degrees from the horizontal position, as shown in FIG.
8B.
[0074] While reducing the height of the dish member at one side
restricts the range of directions in which the adapter can be
tilted, it saves material. Of course, if omnidirectional tilting is
desired or required, the height of the lower adapter section 36''
could be uniform.
[0075] FIGS. 8A and 8B show the lower adapter part 36'' surrounded
and supported by in-fill 100 which is intended to prevent soil from
entering between the lower adapter section 36B and the underlying
top surface 12A and allowing frost-heave to lift the lower adapter
section 36''. The in-fill 100 may comprise concrete or mortar
applied around the lower adapter section 36'' during installation.
Alternatively, it may be formed around the part-spherical lower
adapter section 36'' during manufacture and the resulting two-piece
lower adapter section, having a part-spherical metal upper surface,
flat annular concrete/mortar lower surface and generally
cylindrical outer surface, shipped to the installation location as
one unit.
[0076] It is also envisaged that a greater range of height
adjustment may be provided by interposing one or more spacer rings
between the components shown in FIG. 3; for example between the
inner frame lower portion 20B and the outer frame 22.
INDUSTRIAL APPLICABILITY
[0077] Manhole assemblies embodying the present invention allow
adjustment of the slope and height of the manhole cover, as
necessitated by resurfacing a road surface and/or by frost heave of
the surrounding ground. They may allow adjustment of the lateral
position of the manhole cover. To some extent the manhole cover may
be self-adjusting. Manhole assemblies embodying the invention also
may have an improved self-levelling feature which better allows
automatic height adjustment when the road level rises, for example
due to frost.
* * * * *