Note: Descriptions are shown in the official language in which they were submitted.
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Backqround of the Invention
This invention relates to manhole cover supports
~or emplacing over and raising the effective grade of an
existing manhole cover receiving structure such as the
- usual cast iron manhole cover frame, and more par-
ticularly to manhole cover supports having wales and/or
base portions that are box members, especially those
~; cover supports that are arcuate in plan.
For simplicity the term "existing manhole cover
receiving structure" is used hera to refer to the
existing, i.e., fixed in~place frame ox other seating
receptacle for a removable cover or grating that covers
an access hole (i.e., hand hole, tool hole, manhole,
catch basin or the like~. The term "manhole cover" is
used to refer to the removable cover or grating over
the access hole. The resulting assembly of a receiving
structure and a manhole cover ordinarily is intended to
bear vehicular traffic. The term "manhole cover
support" or simply 'icover support" here means a
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structure that fits over the existing manhole cover
receiving structure, raises its grade, and thereby
accommodates a cover or grating at the new elevated
grade. The access hole covered is a utility enclosure
serving, e.g., an electric, gas, water, sewer or storm
drainage system.
Ordinarily the instant cover support f inds its use
when a roadway such as a street or highway is resurfaced
- with an added layer of paving material. Typically
asphalt concrete is overlaid or repaved to estàblish a
higher grade. It then is advantageous to mount the
inventive cover support atop the existing manhole
; receiving structure. Prior art on manhole cover
supports and manhole cover frames can be found in U.S.
patents 4,281,9~4, 4,236,358, 3,968,600, 3,773,428,
: 4,097,171, 4,302,126, 3,891,337 and 1,987,502. Thefirst four of these are for inventions of t.he applicant.
Axle loads up to 40,000 pounds must be resisted by
many of these cover supports as well as serious impact
loads from vehicles and snow~plows, a variety of
temperature effects, steam leaks, splllage, etc.,
without permitting a hazardous dislocation of the cover
support or its cover. Often it is desirable also to
- cushion the cover a bit for resisting wear or reducing
noise, or to seal the cover and its cover support
against a substantial and possibly overloading infiltra-
tion of surface water, e.g., storm drainage that
otherwise would enter a sanitary sewer system at various
manhole locations. Adjustability of the cover support
~ in~peripheral dimension;`~and ~height also is important for
accommodating the wide range of~spe~ciflcations to be
m~t. ~ ~
~ Installing, adjusting,~loading and unloading and
-~ ~ otherwise handling manhole cover supports and removing
~; ~ 35 the covers therefrom usually is~ done with powerful and
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indelicate tools such as picks, pinch bars, crowbars,
tongs, heavy hooks and the like. Deformation o~ the cover
support can occur, particularly about its upper edge which
is nearest the road surface. Also, the upper edge usually
is the handiest area for applying lifting and other tools.
Deformations of the edge never are good, and they can
render the opening of the support unfit for service.
Hence, overall ruggedness and stiffness against
deformation, especially at or near the top rim, and
resistance to displacement are major concerns about manhole
cover supports.
On the other hand, a relatively light construction of
the cover support, in comparison to the ponderous cast iron
frame that usually initially supports the manhole cover
when the first paving is laid, can be very desirable,
provided, however, that an inordinate amount of the
ruggedness, stiffness, and resistance to displacement or
dislodgement is not sacrificed. Usually a main place for
weight reduction is in the lateral keeper for the cover.
Another place is in the base of the cover support.
ClearIy, the economics of manufacture, handling and
installation all are generally in favor of lower weight.
A relatively thin wall keeper would normally be of steel,
rarely no more than about 0.1 inch (12 ga.) thick, usually
less.
The instant cover support is an improvement in a cover
support with box members, particularly the support of U.S.
Patent No. 4,872,780. That support combined a reasonably
; low overall weight with a desirable high degree of
stiffness; the present improvement makes the support
manufacturingj eg. by cold forming, appreciably easier, and
it provides a cover support wherein the metal does not need
to~ be~subjected to as much stretching, straining, and
attendant thining and possible deterior-
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ation, or the risk of a folding or crimping-in of metal
around an inner periphery of the support.
Additionally, this improved cover suppart can be
adapted readily like its parent support to be sealed off
against water infiltration and to cushion the cover. It
can be made adjustable in its outer perimeter if
desired.
Broad Statement of the In~en*~on
One aspect of the instant invention is an improve-
ment in a manhole cover support for mounting on an
existing manhoIe cover receiving structure and raising
~he effective grade thereof, the support having a metal
body comprising a base portion with a peripheral ledge
portion that projects inwardly, a lateral keeper
portion khat extends from the base and rises from the
outer edge of the ledge portion, and a reinforcing wale
that is substantially coextensive with the top of the
keeper p~rtion and projec-ts outwardly therefrom, the
wale and/or the base portion being box members. The
improvement comprises having a substantial part of the
box member constituted of at least one piece of steel
that is distinct from the rest of the body structure and
is attached thereto for completing the box configura-
tion.
Another aspect of the instant invention is animprovement in process for making the metal body of an
arcuate-in-plan manhole cover support, the body
;comprising a base~portion with a peripheral ledge
~ portion that projects i~wardly~, a lateral keeper
portion that extends from the~base and rises from the
outer edge of the ledge portion, and a roinforcing wale
that is integral with tha top of the keeper portion and
~projects outwardly, the wale and/or the base portion
35~ being box members. The improvement comprises: forming
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a substantial part of each box member from at least one
piece of metal sheet that is distinct from the rest of
the body structure; and attaching said at least one
piece onto the body for completing each box configura-
tion.
Brief Description of the Drawinas
Figure l is a plan view of a 4-segmented square
expansible manhole cover support with turnbuckle
spreader bolts at about the middle of each side o the
resulting sover. A rubber plug for the left side joint
is shown withdrawn to the right. Figure lA shows the
profile of the plug in elevation.
Figure 2 is a cross sectional elevation, on an
enlarged scale, taken through plane A-A of ~igure 1.
Figure 3 is a fragmentary.plan view of one end of
a round split ring cover support that can have a
tapered steel shaft connecting the two ends of its box
member wale portion and a spreader screw in a;tapped
plug end of its box member base portion. A projecting
screw head (not shown) acts against the opposing
plugged end (not shown) of such base portion.
Figure 4 is a vertical cross section, on an
~ enlarged scale, taken through plane BB of Fiyure 3.
Figure 5 is a vertical cross section, on an
enlarged scale, taken through plane C-C of Figure 3, and
Figures 6, 7 and 8 are fragmentary vertical cross
sections of various wales alternative to the one
depicted in Figure 2.
Best Mode For Carrying Out The~Inventiop
Reference is made to Figures l, lA;and 2. Arrow 1
r~efers gsnerally ~o the ~square~cover~s~pport. Seat 41a
is~the~top surface of the ¢ast ductile iron (grade 60-
35 ; 45-12 or 536) base portion 42a of the lower left
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quadrant of the cover support. In this form, the base
portion 42a is of a solid construction. The vertical
sheet steel keeper portion 43a rises from the base
portion 42a. The bottom of the keeper portion 43a is
welded to the base portion 42a. The keeper portion is
of 13 gauge (0.09375") steel. The top edge of the
keeper portion 43a is bent over to provide a short
flange 45a (Figure 2) beneath U-shaped channel 44a, a
13-gauge sheet steel piece. The ends of channel 44a are
welded by welds 21 and 22 to the keeper portion 43a to
form a hollow wale portion 46a.
Turnbuckle bolt 48a is operated by wrench grip 49a
to widen or narrow the gap between this lower left
segment and the one shown above it. As the four
quadrants of this cover support device are symmetrical,
the numbers of like parts of each quadrant are given the
same arabic numerals all around and are dist~nguished
from each other only by lower case letter subscripts.
Also crossing this gap is tapered steel shaft 47a. Its
untapered end is welded into wale 4Oa. The tapered end
of shaft 47a fits slidably into the hollow wale portion
46b.
one of the threaded ends of turnbuckle bolt 48a
projects directly lnto the upper end of base portion
42a, entering at a bevelled-off-at-the-botto~ en~rance
to the base segment. The bolt can extend into recess
51a in the bottom of that base portion. The other
threaded end of turnbuckle bolt 48a is of opposite
thread. It projects directly into the lower en~ of the
base portion 42b, and it can~extend into recess 51b
therein.
Soft rubber~plug 3~6, notched~on its upper left side
for shaft 47a and below~that for turnbuckle bolt 48a and
~nut 49a, is shown withdraw~ from the gap between the two
~ 35 left side segments. The other thrae joints have like
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plugs, not shown, for stopping the entrance of water at
the joints. In Figure lA the notching is mare evident
in profile. Thus, plug 36 has upper notch 37 for shaf~
47a, notch 38 for bolt 48A and recess 39 in notch 38 for
the nut 49a. The plug can be cut to width after
expanding the cover support into place, then tapped into
position. In place of plugs, one can fill the joints
with a plastic foam comprising a polymer, which foam
expands, gels and dries in place into a flexibla solid
after having been dispensed as a fluent material into
the cavity of a joint.
In Figure 2 an 1/8" thick ~rictional retention
member portion 54a is visible. It adheres to the
outside of the base section 42a. Member portion 54a is
peripheral to the base section 42a and is of a tough
vinyl plastisol. A cushioning and sealing layer of like
material can be deposited all over seat portions 41a,
41b, 41c and 41d, if desired.
Referring to Figures 3, 4 and 5, the arcuate end of
a fragment of a split ring cover support is shown in
plan view in Figure 3. An iron plug 62, with threaded
hole 63, is welded into the end of the base under seat
61. Apart from its plugged ends, the base under seat 61
is hollow, being formed of 14-gauge sheet steel by the
generally U-shaped arcuate channel 69 welded at its free
ends, as at 28 and 29, onto the inside and bottom of the
sheet steel riser member 64 of like gauge. The annular
wale 66 is also hollow, being ~ormed of a generally U-
shaped 14-gauge sheet steel channel welded to the bent-
over flange 68 at the top of riser 64 and to the outsideof the riser 64 somewhat below the top with welds 31 and
3~2.
The pair of adjacent ends~of the spllt ring wale
can be bridged, if desired by a rod or flange (not
shown) extending out of hollow space 67 and into the
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corresponding space of the adjacent end of the wale.
The threaded hole 63 is to accept a spreader screw (not
shown) that can operate across the gap with its head
(not shown) against a welded-in iron plug reaction
member (not shown) in the other end of the split ring
base, that other end not being shown
Figure 5 shows the vertical cross section C-C
through Figure 3. It illustrates the box member base
and wale as described in connection with Figure 4,
except that the interior of the base under seat 61
contains no iron plug.
Figures 6, 7 and 8 show the vertical cross sections
of modifications of wales that can he used in a
structure like that of Figure 3. Thus, in Figure 6 the
wale is made by welding angular sheet steel piece 72 to
bent-top riser 73 with welds 33 and 34 to form an
annular hollow wale 74; the wale is substantially
triangular in vertical cross section. In Figure 7
angular steel piece 78 is welded to riser 76 and its
flanged top 77 by welds 36 and 37 to provide hollow wale
78. In Figure 8 an annular tubing 83 is welded, as at
38 and 39, to the riser 81 and its bent top 82. The
riser 76 has a bent-over top flange 82 that conforms to
about a third of the exterior of tubing 83.
While the cover support embodiments depicted are
for circular and~ square holes, it is contemplated that
rectangles, triangles, ovals, etc. also are possible
shapes for cover supports in accordance with invention
principles. If tha supports are to be rendered
adjustable as to their perimeter, usually turnbuckle
means are used at the j;oints. Attaching o~ distinct
` ~ steel pieces to iron or steel here preferably is done by
welding the parts together. Howevert other attaching
methods can be used, eg. bra2ing, solderingj ~iveting
and/or bolting.
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Suitable polymers that can be formulated for use in
the compressible retention component and for water seals
herein include natural and synthetic rubbers, cork
compounds, water resistant ionomers, various vinyl
polymers and copolymers such as polyvinyl acetate-
polyethylene-acrylate copolymers and polyvinyl chloride
homopolymers, polyurethanes, polyesters resins, epoxy
resins, styrene-containing copolymers such as ABS and
butadiene-styrene or isoprene-styrene copolymers,
lo polyolefins and copolymers containing ole~in units, and
aminoplasts~ Plasticizers, pigmentation, stains and/or
mineral ~illers such as talc, carbon black, etc.
commonly are employed in their recipes. The best
retention components appear to be elastomeric. Many of
them can be foamed and preferably are foamed only very
slightly: this can ~ofte`n them a bit, and it makes them
slightly less dense than without the foaming. Latent
foaming agents reactive upon warming and/or catalyzing a
film of ~n uncured polymer-providing material coated on
a cover support are preferred. Curing the polymer-
containing with heat, ultraviolet or electron beam
radiation and/or catalysis can be practiced.
Customarily, it is of advantage to prime the metal
with a bonding agent or use à bonding treatment to
secure the best bond of the retention component or a
water sealing element to metal. Some polymers can bond
well without this, e.g., epoxy resins. However, the
bonds of most are improved by such priming and/or
~ treating.
A preferred foamed plastisol~formulation for the
retention component is of Shore A Durometer hardness
about 20-70, and preferably about 50-65, as are the
water seals. The plastisol is com~ounded principally
from low molecular weight polyvinyl chloride resin
~plasticized heavily w1th a conventional phthalate ester
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plasticizer. It contains minute percentages of
stabilizer, red pigment and ozodicarbonamide blowing
agent. Another preferred formulation of about th~ same
Shore A Durometer hardness is a flexible polyol-
polyurethan~ foam, slightly elastomeric and rubbery.
Some polymer recipes nead heat to cure and foam, even
with ca~alysis, and others cure and even foam at about
room temperature (78~F.). The degree of foaming in both
these plastisol and urethane formulations is very
small, and it could be called almost microscopic and
slight - the bubbles are closed-cell and tiny. In some
cases, especially where sealing is to be maximized and
strength considerations are secondary, a fair amount of
foaming and a resulting softened and less dense foamy
structure can be tolerated, e.g., Shore A Durometer
hardness of 20-55.
The preferred foamed plastisol usually is sprayed
on the area to be coated. It is advantageous to spray
it onto the hot metal cover support body (370-380F.)
and let it cure (harden and toughen) and foam a bit. If
extra foaming and/or curing is desired, the coated part
can be further warmed at 380-400F. for up to a few
minutes. Thickness of the retention element must be
between about 0.4 and 400 mils to take care of, on the
thinner side, minor surface irregularities while, on the
thicker side, neither rendering the seat of the cover
support too constricted to accept the same cover that
was used for the existing caæt;iron frame (or other
cover-seating receptacle) nor~lacking in me~al-to-metal
bearing surface between its base and the seat of that
existing frame.
~Metal surfaces should be cleaned to accept the
polymeric material if it is to be bonded to the metal.
~ ~Then a customary bonding agent such as Chemlok #218
; 35 ~(Manufactured by Lord Corporation, Erie, Pa.) is
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applied, dried and warmed. Various other useful bonding
agents are available such as a Pliobond type ~made by
the Goodyear Tire and Rubber Company).
As shown above, the preferred materials of
aonstruction for mos~ of the cover support, i.e., the
body and various elements of the body, are o~ a ferrous
metal, e.g., steel and/or cast iron, particularly cast
ductile iron. Other metals can be used where their
special properties are desirable and their cost can be
tolerated), e.g., stainless steel, high tensile strength
steel, wrought iron, bronze, brass, etc. Desirably
screw threads will have nylon locking patches.
Many modifications and variations of the invention
will be apparent to those skilled in the art in the
light of the foregoing detailed dis¢losure. Therefore,
it is t~ be understood that, within the scope of the
appended claims, the invention ~an be practiced
otherwise than as shown and described.
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