Note: Descriptions are shown in the official language in which they were submitted.
~043~17
ADJUSTABLE MANHOLE FRAME AND
METHOD OF CONSTRUCTION AND INSTALLATION
BACKGROUND OF THE INVENTION
Field of the Invention
The field of this invention resides in the area of manhole frames
and more particularly relates to adjustable manhole frames.
History of the Prior Art
The standard practice in manhole installations is to supply pre-
cast concrete manhole sections to be assembled on the job site. These
manholes extend from the depth of the pipe to 12 inches below the road
surface. This 12 inch space is for the installation of the frame and
manhole cover which vary in height from 4 to 10 inches. The void
between the bottom of the frame flange and the concrete manhole is
filled with either brick or mortar, cement block and mortar, or pre-cast
concrete rings mortared in.
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After installatioll of the frame, available fill material con-
sisting of gravel or a combination of gravel and dirt is deposited
around the exterior of the manllole and frame, and the fill is then
compacted witll whatever means is available, leaving 2 inches or
more on top for the final paving material. Invariably settling
occurs within a s~lort period of time resulting in a separation and
cracking of the final paving around tlle frame. This settling pro-
cess develops potholes that require constant patching, and over a
period of time seepage of surface liquids such as water, gasoline,
o~ and in cold climate areas, water carrying salt causes deteri-
or.ation of the support base under the frame. In areas of severe
deep frost penetration, entire sections of frame and base are
lifted above the road surface. A great;number of structures have
to be repaired whicll means digging out and rebuilding the bases.
Where all brick and mortar man]loles exist in the older systems
traffic shock alon~ witll freeze and ~haw cycles loosen bric]cs in
the cone section as deep as 2 feet or more below the road surface.
This situation usually requires extensive excava~ion and rebuild-
ing of the entire cone section.
~ t the present the vast majority of manhole frame members are
of a non-ad~ustable type, tllerefore any needed change means digging
them out to raise, lower, repair or replace worn or broken frames.
The horizontal stability of prior art frames having a flat
base surface resting on the nlanhole cone or brick support depends
upon the surrounding backfill and pavement to hold the frames in
position. Frequently, especially during wet periods, such frames
can be forced laterally out of position over the manhole which dis-
placement helps initiate the deterioration of the frame support and
ultimate collapse of the frame.
It has long been desirable to have a simple and easy way of
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providing an adjustable man~ole frame memher to avoid the necessity
of digging up ~he entire manllole frame out of the ground wSlich pro-
ject entails a great deal of labor wit!l air compressor equipment
and jack hammers to cut through the pavement and to loosen the
compacted fill with tlle accompan~ing great expense and
traffic disruption In addition, the base support may also have
to be dug out and rebuilt due to ingtability of either or both
frame and support base as inevita~ly traffic moves the franie while
rreeze and thaw cycles move and destroy the base.
In an attempt to raise manholes without the necessity of dig-
ging out the entire structure, a prior technology utilized ring
members for placeniell~ upon existing frame cover seats into which
the covers are replaced. These ring members have limited use as
their minimum overall height is greater than the thinner layer of
pavement used today. ~lso, if they are not carefully installed or
~o not properly fit the cover seat and cavity, they could be dis-
lodged and cause traffic accidents.
Many attempts to oreate adjustable manhole frames have been
made. One is the "Preko"T-M- adjustable manhole f~ame disclosed in
V.5. Patent 3,858,998 which includes a second frame within an
outer frame with screw adjustment means to raise or lower the in-
ner second frame member in relation to the outer frame member so
that if the road is raised, one turns the screws on the manhole,
and the inner frame will raise or lower the manhole cover to the
desired height.~ These "Preko" adjustable manhole frames have not
gained widespread usage in t'he industry because of their higher
initial cost due to the complexity of machining that must be done
to create them and to the inherent fear that the screw elements
might jam and fail to operate after the frame had been installed
for a long period of time.
Another adjustable type is the "self-level", a United Kingdom
invention disclosed in U. 5. Patent 4,174,183. This frame is in-
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st:alled during paving operations w}lic~ requires hot pAVement and
also the use of a pavemellt roller for compression of the paving
material and the posi~ioning of the frame. ~ special exterior
concrete ring is also required which is mortared to the base man-
hole. This frame is ~ ited to shallow heigllt adjustments, alld
when the frame is raised, a void can bb created that could trap
water which, if frozen, could force the unit up into tlle traveled
way. Further, unless care is taken to properly fill and compact
around the frame exterior, surface and underground liquids could
undermine and/or deteriorate the frame support.
SUMM~RY OF T~IE INVEMTION
It is an object of this invention to provide a stronger and
mc-re permanent frame support impervious to the elements that affect
the present material of brick and mortar.
It is a further object of this invention to provide such
st:ronger frame member in a design tllat provides a reliable and
heigllt-adjustable manhole frame which is simple in design and eco-
nomical to produce and install.
It is yet still another object of this invention to provide
a stronger and more permanent frame, cover and installation method
in a design that assures long life, is not affected by traffic
shock, and is impervious to t~le elements that affect present ma-
te!rial .
M~ improved frame design incorporates all of the necessaryf~atures to provide lifetime strengtll and wearing qualities plus
st:ability in any necessary position. The outer edge
oi the wide surface is tapered downward to prevent damage
to either the frame or the plow or the scraper during
snow or ice removal. The surace width and arched
shape of the bottom of the rim frame make it much stronger and
more durable than present types. The deep lettering pattern of the
surface provides anti-skid protection and contains arrow designs
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to indicate positions for lifting the frame. The exterior vertical
wall of the frame rim extends downward.and contains a series of
large openings and deep tabs or teeth that help secure the frame
into the frame support member to prevent dislogdement. The above-
mentioned openings extend into tlle main arch in t~le rim W]liCIl with
the tapered skirt desi~n discussed bëlow provides.the major sup-.
port of the frame. In addition these openings act as vents to
allow air to escape during the pouring of the concrete frame sup-
port member and wllen tllese openings are fill~d witll concrete the
total support and retention area of tlle frame.is greatly increased.
~ompact stora~e and saEety of thé frames is derived
irom the shape of the skirt.
~he interior wall section or skirt of the frame is offset to pro-
vide stackability of frames in a.manner that.locks each frame into
l:he cover cavity.of the lower frame. This offset jog in the
skirt desic~n also provides greater frame stability when in a
raised position as.tile upper anglé of the exterior skirt then pro-
vides a wide void for the filler material and thus a greater sur-
ace support than is provided ~y the.main arch and vent openings
alone The frame design is suc}l that filler may be inserted and
packed easily and thorougllly without the need of.wide pavement re-
moval around the exterior of the frame. The long frame skirt adds
to the stability and.provides maximum strength.under.the cover
seat. F~ame seats are machined deeper than cover thicknesses
so that the cover is recessed below the frame's surface to elimi-
nate piow damage and reduce traffic impact. Due to the exterior
taper of the skirt, the frame may be angled sharply to meet the
road grade while still maintaining vertical wallsof the support
base.
The basic structure of my improved adjustable rnanhole frame
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can consist of several solid and durable frame and pavement
support members as follows: a concrete support formed in place
between form members; or concrete support pre-cast at a
location other than the job site then after the concrete is
sufficiently cured the pre-cast unit i5 trucked to the job
site and installed; or brick and mortar support is formed
in place using one form member to expedite the placement of
the frame and bricks or lastly the brick and mortar support
can be formed in place without the use of forms.
The inner and outer form members may be made of steel
or aluminum and are held apart a distance determined by the
size of the base of the concrete manhole. There are a
plurality of height adjustment devices that include hooks at
the ends thereof that are adapted to be inserted under the
outer rim of the iron frame. These height adjustment hooks
are attached to a bracket that rests on the top rim of the
inner form or the bracket may be supported on three lifts
that engage supports on the inside of the form. These lifts
are used to raise the frame a few inches above the form thus
eliminating the need if necessary of stacking a second form
to raise the frame above the first form. Each inner form
also has one or more devices that expand or contract it,
such as turnbuckles or levers. The lower section of the
inner form is expanded to grip the inner surface of the
concrete or brick manhole while the upper section is expanded
to grip the iron frame and support it during the concrete
pouring process. Each outer form also has one or more
devices for its expansion and contraction. The lower portion
o the outer form contracts to grip the outer wall of the
concrete manhole while the upper portion of the form is
contracted to cre-
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ate an inward slope of the concrete support to be poured. Thisslope is a deterrent to lifting of the concrete support by reezing
action of the e~terior back fill. E~ch form also includes a num-
ber of leveling devices disposed at the lower portions of the forms
These leveling devices rest on the concrete manhole and keep the
forms in the desired position. In the event that the manhole is
so deep in the ground that the forms are not high enough to reach
the surface level and accomplisll the installation, there can be
provided inner and outer stack support members, each with provi~
sions for stacking a second set of forms above the first set.
Where undersize frames are used that create a void between
the form and the cone opening, a set of spacer pla~es is used
around the exterior of the inner form and rest on the inner edge
oi the cone. These plates are held by the leveliny devices and
after the poured concrete has set, they are removed for reuse.
After the forms are positioned on the concrete manhole struc-
ture in the ground, the height adjustment hooks are then inserted
under the frame. The frame can now be elevated thereby to the
proposed or actual road level and angle. The form expansion de-
vices are expanded to hold tlle inner form tiyht to the manhole and
frame and the height adjustment bolts are removed. The concrete
is then mixed and poured into the void under the frame and between
the inner and outer forms and is pushed up into the arched areas
of the frame. When the concrete has set, a trowel is used to
remove excess concrete from the exterior of the frame rim and then
to slope the concrete downward and away from the frame rim to the
outer form
to allow sufficient depth of pavement around thè frame. The
forms are later removed and the structure is then ready for paving,
An optional installation method that is desirable in high
17
~:raffic areas and du.ring low temperature pexiods such as experi-
enced in nortllern winter climates is to pour the concrete for the
f-rame support in some area other than in the street. ~irst a
~epth measurement in four locations is made at tlle site by rernov-
ing the manhole cover and measuring from the road surface to tlle
concrete manhole. Tllen the frame and forms may be set up else-
wllere on a surface to which the concrete will not adhere and the
concrete poured and the excess material removed. The frame support
is allowed to cure and then it is transported to the manhole site
alld installed as described.in detail below.
Where brick and mortar manholes have deteriorated not only in
the frame support area but also throughout cne or more brick layers
:in the upper cone area, the frame and concrete support can be ex-
tended around the exterior ol the brick cone to protect the bricks
:Erom further ground pressures and give the entire cone area and
.Erame support stability and permanency~
When new sewer lines are installed., the roadway invariably
settles leaving the manhole higll and subjected to severe traffic
impact. In freezing areas the manhole is additionally subjected
to breakage by snow-removing vehicles. The frame of tllis inventior
can be installed an.inch or more below finish grade and raised
with filler material to the paving height. After the roadway set-
tles, the frame can be lifted off and some or all of the filler
removed to easily lower the frame and cover.
In order to raisç a manhole frame at a later time, bars or
digging picks are driven through the pavement into lift holes
formed in the iron frame that are indicated on the top surface of
the frame by an arrow design. The frame is pried up to the height
of the new grade and blocked up with wedges.
Cement slurry is 'then packed into the void between the
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:120~3~7
frame and frame support and the surface is later repaved.
~ nother desirable feature of the frame design is the ability
to stack frames for storage and transportation. The skirt loca-
tion and interior shape are s,uch that the skirt fits into the
cover cavity o~ the lower frame. Thc area needed to store a plu-
rality of these frames is less in both vertical and horizontal
dimensions.
In extemely severe locations such as very steep inclines
where heavyweight and/or l~ig~l volume traffic is encountered, the
frame can be securely locked to the concrete, both in its original
installation and after being raised or lowered. Frames are pro-
vided with two opposite lloles in the lower end of the skirt, and
prior to pouring the concrete frame support, two steel rods are
inserted through these holes and extended into the area where the
concrete will be poured. Later, should heigh* change be necessary
these pins are retracted, the frame repositioned, its new height
holes drilled at the new depth, and the pins are reinserted.
BRIEF DESCRIP'rION OF TIIE ~R~WINGS
F:;gure 1 illustrates a cross-sectional view through a side of the
adjustable manhole frame of this invention.
Figure 2 illustrates a perspective elevational view of the frame
support witll the outer form opened.
Figure 3 illustrates an elevational view of a section of the
frame showing the air escape vents.
~igure 4 illustrates a top plan view of a section of the frame.
Figure 5 illustrates a cross-sectional view of an inner frame with
bricked-in support fraMe.
Figure 6 illustrates a cross-sectional view of a frame raised
from its ori~inal installation.
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DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
Figure 1 illustrates a cross-sectional view through
the side of the adjustable manhole frame of this invention
during its installation on top of the manhole cone. Seen
in this view on the inside of cone 16 is positioned inner
form 12. On the outside of manhole 16 is positioned outer
form 14. These inner and outer forms are provided with means
to expand or contract them as seen in Figure 2, being a split
within the ring such as inner form split 51 which allows
the form to pass by itself when turnbuckle 50 is tightened
or expanded. An outer form expansion member turnbuckle 52
can be provided to close the split on the outer form but
a long bolt can also be used. More than one expansion/
contraction member can be provided, each at different levels
along the height of the form. In practice the base of the
inner form is tightened, expanding outwardly against the
inside of top of manhole cone 16 and the base of the outer
form 14 is tightened inwardly around the outside of the top
of manhole 16. In some instances the inner form may not
meet the inside top of manhole cone 16 or it may be desirable
to use a frame member 10 o~ a different size then the
diameter of the inner top opening of manhole cone 16. There-
fore a series of inner leveling bolts 20 or equivalent
unthreaded slide pins are disposed through the inner form
12 and extend outward to a point where they are adapted to
rest upon and contact the top of manhole 16. There may be
a plurality of these inner leveling bolts 20, two of which
can be seen in Figure 2. The same kind of leveling bolts
or unthreaded slide pins can be used in outer form 14. The
outer leveling bolts 22 or unthreaded slide pins, one of
which can be seen in Figure 1 and a series of which can be
seen in Figure 2, are adapted to rest upon the top of the
manhole cone to support the outer form on top
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12~;)43J~
of the cone. When there is a space between the top of the manllole
colle and the inner form, this space must be filled so that the
collcrete does not pour out between manllole cone 16 and inner form
12. A pluralit~ of spacer pla~es 42 may be positioned so that the~
overlap one anotller and extend from tlle inner form, under leveling
bolts 20 and onto the top of manhole cone 1~. In one embodiment
an attached sleeve 21 can be provided in the center of each
spacer plate allowiny t~e sp~cer plate to be connected to each
inner levelling bolt to prevent loose spacer plates $rom falling
into the void and being lost down the manholè. The spacer plates,
oE whicll there may be six in a desired configuration, overlap one
another such as seen with spacer plate 44 overlapping spacer plate
42 in Figure 1. A series of spacer plate removal tab members 46
are affixed each to the base of each spacer plate to grasp onto
so taht they can be removed after the concrete has been poured and
set and inner form 12 removed. The inner and outer forms as dis-
cussed above can be provided'wit}l more than one expansion or con-
traction member which may be an upper~and lower expansion/contrac-
tion member so that the upper portion and lower portion of each
form can be moved independently of one another. It is often de-
sirable that the outer form's lower expansion member be tightened
so that outer form 14 tightens against manhole cone 16. It is
further often desirable to expand inner form 12 so that it will
contact and tighten against the inside of manhole cone 16 at the
inner form's bottom. It is best to position the spacer plates
nder the inner levelling bolts 2~ before such tightening takes
place.
Once the forms are in the desired position, one can position
on the top of inner form 12 height adjustment'device 18.
:~f one wishes to raise tlle top of frame 10 higher than the top of
inner form 12, three adjustable lift members 7, 8, and 9 seen in
Figure 2 can be attached to t}le inside of the form member extend-
ing thereabove and on eacll of which an arm of height adjustment
device 18 can rest. In a
preferred embodiment three hook members 24 hang down from height
~2043~7
adjustment device 18 and can be utilized for the positioning
of frame 10 at its desired height and angle inside and
against inner form 12. Height adjustment device 18 consists
of a T-shaped member whose arms extend beyond inner form
12. Apertures 24 and 26 and elongated aperture 28 are
provided to receive hook members 24 which are threaded at
their tops and on which are nuts 27 with handles to support
them at various adjusted heights from height adjustment
device 18. All apertures can be of the elongated type in
some embodiments. The hook extending from aperture 28 is
adjustable not only vertically by movement of said nut but
also horizontally in the elongated aperture 28. Hook
members 24 extend downward and curve around in a hook-like
fashion at their bottoms ending in a crosspiece 30. This
hooked portion passes easily through an arch in frame 10
and crosspiece 30 is retained by the lower downward extending
portions of the arch. Crosspiece 30 does not extend
horizontally a distance greater than the curvature of the
frame and may be curved to match that curvature in some
embodiments.
If the frame is to be at an angle, one then adjusts
the hook member heights by rotating each respective nut so
that the frame is at the proper angle to be parallel to the
level of the paved road. If the frame is to be parallel
with the manhole cone, one would set all the hook member
heights the same. The height, though, is determined by
measurement of the frame to the proper height of the roadway.
Once the frame is securely positioned, the upper portion of
the inner form is expanded so as to grip the frame tightly
and then the height adjustment device and hook members are
removed completely from the frame by loosening the nuts and
lifting the hook members free of the frame. Frame 10 will
still remain in position being held by the pressure of the
inner form against it. The concrete is then poured forming
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1204317
frame support member 11 as seen in Figure 2.
The height of the frame can be adjusted by various
other means as discussed below but in some embodiments one
can set the frame lower than its normal position and then
once the concrete of the frame support member has set, one
can wedge the frame up and pack cement mortar material there-
under so that it is at the height of the road. Should it be
desired to lower the frame in the future the pack material
81, once frame 10 has been raised up, can be removed. The
frame then can be lowered to a new lower position should
the roadway settle. The frame of this invention includes
manhole cover seat 75 and a very deep arch 70 under its outer
rim into which the concrete of the frame support member is
forced. The concrete can reach up into the uppermost point
of the arch by forcing it under arch 70 from which air escapes
through air escape vents 62. These vents as seen in cross-
section in Figure 5 extend from the top of the arch upwards
to a point near the top of the rim. Air escape vents 62
are also seen in Figure 3 which shows their rounded and in-
wardly tapered configuration as seen in outline in Figure4. This configuration helps to allow the air to escape when
forming the inner portion of the frame support member which
holds frame 11 securely within the arch because of the high
retention characteristics of the portion of the frame support
member that extends up into the arch and air escape vents
and prevents any undesirable movement of the frame. One
can also use an air escape vent 62 as a pickhole to allow
for the easy lifting of the frame by the insertion of picks
under the rim of the frame into such vent. Outer form 14
also may have the expansion/contraction member at its top
tightened more than the bottom so as to create an outward
downward slope of the outer edge of the frame support member
11 which shape increases
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12~43~7
the structural integrity of frame support member 11. The outer slope of tlle
concrete helps to prevent freezlllg groul~d from gripping the unit and raising
it out of positioll.
To raise the frame should the need arise, one can pry up frame 10 by
inserting rods into air escape vent 62 and raising the frame up to a new
position and inserting wedges to hold it in place. Then cement slurry packing
material 81, seen in Figure 6, i9 packed thereunder to fill arch 70 above
original frame support member 11.
The design of frame 10 is critical to the succes3 of this invention. It
should slso be noted that althougll this inventi.on is illustrated and oEten
referred to as relating to the circular type of manhole, it can nlso be
utilized on square or rectangular manhole3 equally 8S well and such uses are
contemplated withill the spirit and scope of thig invelltion. In Figure 5 a
cross-sectional view shows an embodilllellt with a briclced-in frame support 116.
The use of an outer form is optional wllen using a bricked-in frame support.
Frame 10 in the upper left-hand corner of this view has cover seat 75. l'he
cover, a portion 120 of whicll is shown, is recessed below ~op rim 106 of frame
10. This position helps prevent the'cover from being struck by any objects or
vehicles around itg upper edges. At the edge of tlie.top of rim 106, the rim
slants downwardly as top rim bevel 112. Thig slant helps prevent the edge of
the frame rim from being gtruck by vehicles and the like and pavement 74 can
also be bevelled to meet top rim bevel 112. Under top rim 106 is formed arch
70 whicll communicatesjto the outside!of the side of rlm 108 througll a series
of air-escape vents 62. Side 108 of the rim extends downward at an inward
angle 110 which design llelps to allow for later lifting of the frame. Vents
62 are also arcll-shaped along side rinn 108, the top of the arch of each air
escape vent 62 being higher than the top of arch 70 and each air escape vent
62 comlllullicating at a downward slant into tlle open area formed by arch 70.
~180 eacll air escape vent 62 can be tapered as it enters lnto arch 70 as seen
in Figure 4. The inward side of arch 70 continues downward to form the outer
side 102 of skirt 100. Jog 85 recesses the base of outer skirt 102 which
extends downward at an angle toward the in3ide of frame lO. The interior of
frame 10 below seat 75 extends downward as inner side 104 of skirt 100 and
tapers inwardly down to base 118 towsrd outer skirt 102..
Figure 6 shows frame 10 raised to a new level with projections 130 and
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~2()4~31'7
132 to retain the inner cover 134 and tightening bar 136 of
manhole seals which are sometimes used in certain install-
ations. New pavement 77 extends over to bevel 112 at the
new frame height.
The outer inward slope 80 of arch 70 and skirt 102
must be at a sufficient angle to allow packing material 14
to be packed between it and the angular inner surface of
frame support 11. It has been found that more packing
material in area 81 helps to hold the frame securely. If
the angle of the slope 80 of the skirt is too close to the
vertical, it will be in too close proximity to frame support
11 when raised to allow for sufficient packing material there-
between. The more angle 80 of the skirt is to the horizontal,
the greater the amount of packing material that can be placed
between frame 10 and inner support frame 11 along the skirt
and arch. Jog 85 helps make the frames stackable for storage
by recessing the exterior base of the skirt so that the skirt
will fit into manhole seat 75 of the next frame.
Frame 10 can be raised to as many new heights as are
necessary to have the height of the manhole conform to the
new surface level of the pavement. In the embodiment as
discussed above where the frame support member is formed
somewhat below the surface of the roadway to be formed and
then the frame is raised up and pavement material packed
thereunder, frame 10, if it is to be lowered at a future
time, can then be raised up and the cement packing material
14 removed from above the concrete frame support member
allowing frame 10 to be reset at a lower height than its
original installation direct].y on top of the frame support
member to conform to a situation where the roadway has
settled. In some embodiments a series of apertures
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~204.317
82 can be provided near the bottom of ~he skirt through which can
be inserted pins Q4 wllicll would pass througll into apertures ~6
made in the frame support member.
~ hese pins are removable should the frame have to be
moved but when the pins are in positlon, they help to retain the
frame in place on.the frame support member.
The frame support member can be formed away from the site of
the manhole itself. In certain instances such as in areas of high
t:raffic or in times of freezing weather, such frame support mernber
can be formed in other locations and.even.indoors where the tem-
perature might be above 50F. In tllis procedure one would first
measure from.the road surface down to t~le cone. I there is a
brick cone, one can first remove .the top layer of bricks if they
are badly d,eteriorated. If the road is crowned or otherwise at
an angle, one may take several measurements around the perimeter
of the manhole and then set the inner and outer forms up in the
shop and position the height adjustment member and hooks support-
ing the frame at the distances determined from the measurements
from the floor or surface whicll must.be of a material to which the
concrete will not adhere. In this procedure one should position
some wires or rods into the concrete so as to allow.it to be trans-
ported easily by lifting by means o the rods. When one transports
the cast-in-shop frame support member, one can bring it to the site
and dig down on the outside of the cone around 2 inches or 3 inche~,
to remove any loose cement or brick. One can then place a mound
of mortar or mastic on the center o.the top of the cone and then
cluickly lower the concrete frame support member onto the cone to
spread the seal around. One can then fill in any exterior voids
with crushed stones and compact them.
16.
1204.~17
One would then pave around the top of the frame with hot
l~ituminous paving or coalpatch.
In some instances in order to determine'the most ideal setting
for the frame in relation to tlle road, it is desirable to have the
finished pavement as close,as possible to the frame at the pave-
ment's completed level. ~rherefore one may form tlle frame support
member somewhat below the final level so tllat the frame would sit
below the leve~ of the road. Then one would insert the cover on
the frame and coat the entire frame and cover with a diesel fuel
and pave the road rigllt over the frame. Then one would dig out
the top of the manhole cover and frame,wllich will not adhere to
the paving material and raise tlle frame now to the'exact height of
the paved road with pry bars.and then hold it with wedges while
filling in under the frame's arch with cement.
Although the present invention has been described with
reference to particular embodiments, it will be apparent to those
skilled in the art that variations and modifications can be sub-
stituted therefor without departing from the principles and spirit
of the invention.
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17.
