Note: Descriptions are shown in the official language in which they were submitted.
iLZ()8~)ZS
The present invention relates to manhole assemblies and the like
and more particularly to a novel manhole base.
This application is a division of application Serial No. 386,774
filed September 28, 1981.
Manhole assemblies are typically comprised of a manhole base, an
intermediate or riser section and a top section normally designed to receive
the manhole cover. The base section is comprised of a substantially flat
base portion and a cylindrical shaped sidewall extending upwardly therefrom
and integral therewith. Openings are arranged in the sidewall, each being
adapted to receiv~ the end of a pipe for selectively introducing a liquid
flow into the invert or removed a liquid flow therefrom. Manhole assemblies
are provided whenever a change in slope or angular orientation is encountered
from one pipe run to the next. The openings receiving the pipes are arranged
in accordance with the pipe runs connected thereto, the invert extending bet-
ween the side-wall openings may, for example, define a straight line, right
angle configuration, or a Y-configuration (in the case of a base member having
three openings designed for merging two incoming pipe runs and feeding the
combined flow therefrom to a~single outgoing pipe run). It is extremely ad-
vantageous to maintain a smooth flow through the invert of the base member
thence turbulence resulting from misalignment of the invert relative to the
incoming and outgoing pipes significantly increases the development of odious
and toxic gases as a result of such turbulent conditions. In addition, a
smooth fluid flow also serves to maximize flow rate through the manhole base.
Heretofore, manhole bases have typically been formed in two stages,
the manhole base absent the invert being formed at the factory and the invert
being formed at the job site after positioning the manhole base in the ground,
usually five (5) to fifteen (15) feet below surface. Usually at least one
or more workmen descent into the manhole base and set up the channel forming
assemblies. The casting material, typically concrete, is also transported to
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the job site and dropped into the base member frorn ground level through the
manhole assembly and into the bottom of the manhole base, dropping a distance
of the order of 15 feet or more before reaching the floor of the manhole base
The workmen encounter cramped working conditions within the manhole assembly
and are constrained to stand upon the channel forming apparatus during the
time that the casting material is being poured, and while the casting material
is setting. The workmen must also support themselves upon the channel forming
apparatus in order to form the sloping surfaces in the interior of the man-
hole base adjacent to the invert being formed. The nature of the method steps
necessary for forming an invert in accordance with the above-mentioned conven-
tional technique in the manhole assembly base member is such that the operation
is tedious, complex and time-consuming and also fails to provide accurate
alignment between the invert and the sidewall openings to assure smooth flow
through the manhole base and to maximum the flow rate through the manhole base.
It is therefore, an object of the present invention is to provide
a manhole base provided with recesses arranged between each sidewall opening
having a sealing gasket and the adjacent end of an invert for facilitating
insertion of a pipe in sealing relation.
The present invention provides a manhole base which is completely,
simply and rapidly formed at the factory through the use of either a single
pour technique (provided by the above identified parent application) or a
double pour technique (provided by a first divisional application filed of
even date herewith) using method and apparacus for forming an invert in a
manhole base of a manhole assembly.
~ y a bro~d aspect of this invention, a manhole base is provided
formed of a suitable casting material, the manhole base comprising: a base
portion and a hollow cylindrical shaped sidewall extending upwardly from the
base portion, the sidewall having at least first and second openings; an an-
nular shaped sealing gasket arranged in each opening; an invert formed in the
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surface of the base portion and extending between the first and second
sidewall openings, the invert having a substantially semi-circular shaped
cross-section; and a clearance groove provided in the base portion between
the outer ends of the invert and its associated sidewall opening, each
of said clearance grooves extending into the interior of the base portion
from the interior sidewall of the manhole base by an amount which is
sufficient to facilitate insertion of a coupling pipe into each opening
by providing sufficient clearance for the end of the pipe extending into
the interior of the manhole assembly and even in the event that the pipe
~ 10 is oriented at an angle of up to 15 during insertion of the pipe into
the manhole assembly, The recesses preferably are substantially semi-
circular shaped recesses having inner diameters greater than the inner
diameter of the invert to facilitate the insertion of a pipe at an angle
relative to the longitudinal axis of the invert. It is also preferred
that each of the sidewall openings have an inner tapered portion which
tapers outwardly away from the gasket and which substantially merges
with the outward radial end of its associated recess. Still further, the in-
terior surface between the invert and the sidewall slopes downwardly
from the sidewall of the manhole base towards the invert to cause liquid
matter on the interior surface to return to the invert.
Each of the gaskets preferably has a substantially T-shaped
cross-section portion embedded in the casting material and having a resilient
portion ^exEending radially inward from the T-shaped cross-section and
yieldable to receive an end of a pipe, and forming a water-tight seal
with the exterior surface of the pipe.
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The single pour technique is preferably utili~ed in one embodiment
of the invention provided by the above identified parent application to form
inverts of the most typically used designs,thereby lending itself to mass
production techniques. Base members are formed using the single pour method
by employing mold members which form and define the base and sidewall of the
manhole base. Ring-shaped gasket holder assemblies are arranged within the
aforesaid mold members to form and define the openings in the manhole base
sidewall into which the gaskets held thereby are integrally cast. The manhole
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base is cast in an ~upside-down" fashion. The mold member forming part of
the mold assembly is provided with a channcl shaped projection for forming
and defining the invert and is provided with flange portions each defining a
recess arranged between the outer end of the invert and its associated sidewall
opening, which recesses facilitate insertion of a connecting pipe. The mold
member having the channel shaped projection is provided wlth reciprocally mov-
able registration pins insertable into associated locater openings provided
in the ring shaped gasket supports so that, when the aforesaid mold member is
in position and the registration pins are inserted into their associated locater
holes, precise alignment of the invert with the associated sidewall openings
is thereby assured. The casting material is then poured into the molding
apparatus.
When thc cast member has set, the mold mcmbers, including the mold
member utilized to form the invert, are separated from the cast member. The
registration pins are withdrawn from the locater openings to facilitate removal
of the invert forming mold member. The ring-shaped gasket holders are like-
wise disassembled and removed, thereby forming a manhole base having sidewall
openings integrally formed with pipe sealing gaskets and having an invert
whose longitudinal axis is precisely in coaxial alignment with the central
axis of the adjacent side wall opening. The recesses arranged between the
outer ends of the invert and the adjacent sidewall opening provide for either
misalignment of a pipe extending therethrough to facilitate insertion of a
pipe as well as allowing for misalignment of the pipe relative to the longi-
tudinal axis of the invort which may, for example, occur due to settling of
the earth about the manhole asscmbly, as well as other natural phenomena.
The gaskets provide ancxccllcnt water-tight seal between the pipe and the
manhole base sidewal], once the pipe is inserted while at the samc time being
sufficiently resilient to facilitate simple and yet rapid initial insertion
of the pipe end.
iLZ~ S
Thc most widcly used manhole base is comprised of a lincar invert
which is coaxial with an imaginary diameter of thc base membcr, and as a
result, it is practical to produce a mold member which defines the aforesaid
invert due to the large number of base members normally produced through the
use of such a mold member. However, a significant number of base members
frequently require inverts extending between openings which are arranged to
be in alignment with imaginary radii which cooperatively form an angle of
other than 180 . It is thus cost-prohibitive to produce a mold member which
defines an invert for each such invert configuration. As a result, the inven-
tion provided by the above identified parent application in another aspect
further incorporates a mold member having a main body portion and a first
channel-forming projection integrally formed on the main body portion and a
first channel-forming projection which is releasably secured to the main body
portion. A flexible connector extends between the integral and movable channel-
forming projections. Reciprocating registration pins, as were described here-
inabovc, are provided in the mold member and are arranged to be extended radially
outward for insertion into locater openings in the gasket supporting rings
to assure precise alignment between the channel-forming projections and the
sidewall openings in the manhole base. The movable member of channel forming
mold member may be oriented at any desired angle relative to the integral
channel-forming member over a range from 90 to 270, for example, thereby
enabling the formation of a wide variety of base members having two side wall
openings. Automatically operable suction means is arranged within the movable
channel-forming member to releasably secure thc movablc mcmber to the main
body portion, the vacuum condition being releasable upon complction of the
casting and setting of the manhole base. Pneumatic means may also be providcd
as shown in one preferred cmbodiment, for operating thc registration pins in
a reciprocating manner.
The invention further teaches method and apparatus for forming
invcrts in manhole asscmbly basc membcrs utilizing a two-pour techniquc pro-
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vided by a first divisional application filed of even date herewith in whichthe manhole assembly base is formed and cast in a first pour when the sidewall
openings having an integrally mounted gaskets and wherein a flat interior
floor is formed in the base member during the first pour. Thereafter, two
or more channel-forming projection members and cooperating alignment rings
are inserted into the manhole assembly base member by the alignment rings
cooperate with clamping members to secure the channel-forming members to the
base member at each sidewall opening and further assuring precise axial align-
ment between each sidewall opening and its associated channel-forming member.
Once the channel-forming members are so mounted, they are generally axially
aligned along imaginary radii of the manhole assembly base member. Each
channel-forming member is provided with a planar top surface having an upwardly
extending elongated projection. Clamping bars are provided to clamp the in-
wardly directed ends of the channel-forming members to one another to assure
precise angular alignment therebetween and further to assure alignment of
the channel-forming members to that their longitudinal axes lie in a common
imaginary pLane. The clamping bars may be comprised of a pair of operating
clamping members arranged so tht the first ends of the clamping bars cooperate
with fastening means to arrange the clamping bar members at any desired angle
therein. The clamping members, once arranged to obtain the desired angle,
are then clamped to projections on respective ones of the channel-forming
members for securement thereto, whereupon the "second-pour" of the casting
operation is then initiated, the casting material being poured into the in-
terior of the manhole assembly base member and about the channel-forming mem-
bers. ~fter the casting material is poured, but before it is set, the operators
slope the floor of the base member on opposite sides of the invert. Once
the casting material is set, the channel-forming projections and clamping
members may then be removed, completing the two pour operation.
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The two pour operation provided by a first divisional application
filed of even date herewith is ideal for use in forming manhole assembly base
members having two or more openings and cooperating inverts. In manhole bases
in which at least two sidewall openings are provided, the channel-forming
members for forming two of the invert portions are preferably joined with an
intermediate flexible member, as was described hereinabove. The two pour
method provided by a first divisional application filed of even date herewitth
is especially advantageous for use in forming inverts in manhole assembly
bases having one or more sidewall openings, especially three such openings,
the channel-forming members being adapted to be arranged in any desired angle
thereby to form associated invert portions which are in precise axial align-
ment with their adjacent sidewall openings to assure smooth, non-turbulent
flow through the base member.
In the accompanying drawings,
Figure 1 is an exploded perspective view of the molding apparatus
employed for forming a manhole assembly base member provided by the present
divisional application in accordance with the single pour technique of an
embodiment of the invention provided by the above identified parent application.
Figure la shows a perspective view of the channel-forming member
showing the gasket supporting rings, inner cylindrical mold member and wire
frame of Figure 1 assembled upon the bottom plate.
Figure 2a and 2b show perspective views of the top and bottom sides
respectively of the channel-forming member of Figure la.
Figure 2c shows a sectional view of a portion of the channel-forming
member looking in the direction of arrows 2c-2c in Figure 2a.
Figure 3a shows a top plan view of a manhole assembly base member
provided by the present divisional application formed through the use of the
single pour technique provided by a first divisional application filed of even
date herewith and employing the apparatus of Figure 1.
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Figure 3b shows a perspective view of the manhole assembly base
member of Figure 3a with a portion thereof being removed for purposes of ex-
posing the interior construction.
Figure 3c shows a sectional view of one of the sidewall openings
of Figure 3b looking in the direction of arrows 3c-3c.
Figure 3d shows a top plan view of still another manhole base pro-
vided by the present divisional application.
Figure 4 shows an exploded perspective view of the molding apparatus
employed for forming a manhole assembly base member provided by the present
divisional application in accordance with the two pour technique of an embodi-
ment of the invention provided by a first divisional appliation filed of even
date herewith.
Figure 5 shows a perspective view, partially sectionalized of the
manhole assembly base member provided by the present divisional application
cast through the use of the apparatus of Figure 4.
Figure 6 is an exploded perspective view of the apparatus employed
for forming a portion of the invert in the base member provided by the present
divisional application of Figure 5.
Figure 6a shows an exploded perspective view of an alternative clam-
ping bar assembly which may be employed in place of the clamping bar shownin Figure 6.
Figure 6b shows a sectional view of the adjustable portion of the
clamping bar assembly of Figure 6a.
Figures 7a and 7b are front and sectional views respectively of the
positioning ring of Figure 6.
Figures 8a and 8b are perspective and front elevational views res-
pectively of the channel-forming member of Figure 6.
Figure 9 is a perspective view showing channel-forming assemblies
of the type shown in Figure 6, fully assembled within a base member provided
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~208(~;~5
by the present divisional application in readiness for the second pour of the
two pour method provided by a first divisional application filed of evèn date
herewith.
Figure 10 shows a perspective view, partially sectionalized, of the
base assembly provided by the present divisional application of Figure 9
after the invert has been cast and set.
Figure 11 is a perspective view of an assembly for forming an invert
within a manhole assembly base member in accordance with the two pour technique
of an embodiment of the invention provided by a first divisional application
filed of even date herewith for use in base members having large diameter
sidewall openings.
Figure 12 is a perspective view of another alternative embodiment
of the invert forming mold member of Figure 1.
Figure 12a shows a sectional view of a portion of the invert forming
mold member of Figure 12 looking in the direction of arrows 12a-12a.
Figure 12b shows a sectiona] view of a portion of the invert forming
mold member of Figure 12 looking in the direction of arrows 12b-12b.
Figure 12c shows an elevational view, partially sectionalized, of
the invert forming mold member of Figure 12.
Figure 13 is a perspective view of an alternative embodiment for
the invert forming mold assembly of Figure 6 employed for forming base members
provided by the present divisional application in accordance with the two
pour technique of an embodiment of the invention provided by a first divisional
application filed of èven date herewith.
Figure 13a is a perspective view of one of the invert forming members
of Figure 13 showing the manner in which a clamping bar is arranged thereon.
Figure 13b shows a sectional view of a portion of the invert forming
assembly of Figure 13 looking in the direction of arrows 13b-13b.
Figure 14 shows a perspective vicw, partially sectionalized, of a
manhole assembly base of the present divisional app]ication and showing the
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manner in which an invert forming assembly of the type shown in Figurc 13 is
mounted cherein preparatory to casting the invert within the manhole base
provided by the present divisional application.
Figure 1 shows an exploded perspective view of the molding apparatus
10 employed for forming a manhole assembly base member in accordance with the
single pour technique of an embodiment of the invention provided by the above
identified parent application. The molding apparatus 10 is comprised of a
disc-shaped member 22 having an outermost periphery 22a adapted to be received
within the interior of the lower edge of sidewall 12a of the outer cylindrical
mold member 12. The outer cylindrical mold member 12 defines the exterior
wall of the manhole base. The manhole base is cast "upsidedown" as will be
described in detail hereinbelow. Outer cylindrical mold member 12 is provided
with a pair of collars 15, 15 swingably mounted to the exterior of outer cylin-
drical mold membcr 12 by fastening pins 13, 13. Collars 15, 15 are each pro-
vided with a short section of chain 15a, 15a to receive hooks (not shown)
from an overhead crane, for example, for lifting and rotating the molding
apparatus 10 as will be more fully described.
Cy~indrical shaped inner mold member 18 is provided with a hinge
assembly 19 for respectively increasing or reducing the diameter of the cylin-
drical inner mold member 18 for a purpose to be more fully described. Thehinge assembly 19 is initially arranged to increase the diameter of the cylin-
drical inner mold member properly to position member 18 upon member 22, so
that the cylindrical periphery 22e extends into the interior of mold member
18 and engages the inner periphery thereof~ whereby lower edge 18a rests upon
surface 22d of member 22.
The wire reinforcement frame 20 is arranged bctween inner mold mem-
ber 18 and outer mold member 12 so that its lower edge rests upon surface 22d.
Frame 20 is comprised of a plurality of vertically arranged wires 20a and
horizontally aligned circular-shaped wire loops 20b which define the wire
- 10 --
frame 20 to form a reinforcing frame which is mo]ded into the interior of
the cast manhole base, as will be more fully described. The wire frame 20 is
bent to form openings 20c and 20d for receiving the gasket retainer assemblies
16, 16.
The mold member 14 which forms and defines the invert in the manhole
base provided by the present divisional application is comprised of a main
body portion 14a having sloping surfaces 14b and 14c arranged on opposite
sides of the generally cylindrical shaped invert forming projection 14b.
Flange-like portions 14e and 14f arranged at the ends of a substantially
cylindrical shaped projection 14b form recesses within the interior of the
manhole base provided by the present divisional application to facilitate in-
sertion of connecting pipes, as will be more fully described. Registration
pins 14g and 14h reciprocally mounted within the body of member 14 are arranged
to be respectively Moved so as to extend outwardly from the ends of projection
14b or to be drawn inwardly for purposes to be more fully described.
Figures 1 and 2a through 2c show the invert forming mold member,
which is provided with a guideway 14j slidably receiving and mounting regis-
tration pin 14h. An elongated projection 14k is integrally joined to the
inner end of registration pin 14h. Projection 14k extends downwardly through
an elongated slot 141 provided in the underside 14m of body member 14a. A
similar slot 14n is provided for projection 14p which is integrally joined
to the inner end of registration pin 14g. Projections 14k and 14p are recip-
rocally movable as shown by double-headed arrows A1 and A2, in order to res-
pectively extend and withdraw their associated registration pins 14h and 14g.
Projections 14q and 14r, extending downwardly from the underside of mold
member 14, serve as alignment means for aligning member 14 upon the inner
cylindrical mold member 18.
Figure la shows a sub-assembly of the casting apparatus 10 of Figure
1 wherein the inner cylindrical mold member 18 is shown having its lower edge
_ 11 --
1;~086~ZS
suppc)rtecl upon disc-shaped member 22. The reinforcing frame 20 has its lower
edge supported upon disc-shaped member 22 and surrounds inner cylindrical
mold member 18. The projections 14k and 14p, which extend downwardly and
into the interior of inner cylindrical mold member 18, are moved radially out-
ward so that their associated pins 14h and 14g extend outwardly from the end
surfaces 14f-1 and 14e-1 of the mold member 14. The registration pins 14h
and 14g extend into the openings 16b, 16b of the gasket retainer ring assemblies16, 16. The gasket retainer assemblies are comprised of inner and outer ring
members 16a, 16b, arranged to sandwich a gasket 17 therebetween. Note espe-
cially the left-hand ring assembly of Figure 1. The aforesaid gasket 17 is
also shown in Figure 3c in sectional fashion. Ring members 16a, 16b have
been shown in dotted fashion in Figure 3c. As can best be seen from the
last-mentioned figure, the inner or substantially D-shaped portion 17a of the
gasket 17 is sandwiched between inner and outer ring members 16a and 16b. The
substantially T-shaped portion 17b of gasket 17 extends radially outward from
the ring members 16a and 16b and is adapted to be embedded within the casting
material, as will be more fully described. Releasable fastening means (not
shown for purposes of simplicity) are utilized to secure ring members 16a and
16b to one another and to firmly secure gasket 17 thereto.
The outer cylindrical mold member 12 is then lowered upon the sub-
assembly of Figure la, thereby completing the assembly of the mold members
utilized to cast a manhole assembly base. The casting material is then depo-
sited into the inner upper end of outer cylindrical mold member 12, the casting
material being deposited by gravity so as to fall in the direction of arrow
A3 shown in Figure 1, thereby filling the region defined by the lower inner
periphery of mold member 12 and the outer periphery of mold member 18 to
form the sidewalls of the cast member and further being deposited upon the
upper surface of mold member 14. The mold assembly 10 is filled to a level
substantially flush with the top edge 12c of outer cylindrical mold member
- 12 -
)8025
12, and is thcreaftcr allowcd to set. In ordcr to reduce the time required
for the casting matcrial, which is prcferably concrcte, to set, the entire
casting apparatus 10 of Figure 1 is enclosed within a shroud or housing (not
shown) and steam is introduced into the casting material and thereby speed
up the casting operation.
The gasket mouting assemblies 16, 16 are pressed against the interior
wall of outer cylindrical mold member 12 and against a portion of the outer
periphery of the inner cylindrical mold member 18 in order to form and define
the sidewall openings.
After casting material has been set, the entire assembly is lifted
by coupling a pair of hooks (not shown) from an ovcrhead crane (not shown)
to the chains 15a, 15a, and the entire assembly is partially lifted off the
ground and is rotated about collars 15, 15, so as to turn the entire assembly
upside-down, after which the disc-shaped member 22 and the outer cylindrical
mold member 12 are lifted upwardly and away from the cast manhole base. The
clamping assembly 19 is manipulated to cause the martinal portions of the
vertical ends 18b and 18c to overlap one another in order to reduce the outer
diameter of inner cylindricai member 18 to be lifted out of the interior of
the cast manhole base.
Thereafter, the elongated projections 14k and 14p are moved radially
inwardly, i.e. toward one another, in order to withdraw the pins 14h and 14g
from the gasket retaining assemblies, 16, 16. The mold member 14 is then
lifted out from the interior of the cast manhole base.
Thereafter, the fastening means (not shown for purposcs of simplicity)
securing the ring-shaped halves 16a and 16b of each gasket rctainer assembly
16, are loosened and then disassembled in ordcr to remove the gasket retainer
assemblies 16, 16 from the sidewall openings formed thereby. The gasket sup-
porting assembly and gaskct employcd in aspects of the invention provided by
the above identificd parent app]ication and provided by a first divisional
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application filed of even date herewith arc described in U.S. Patent Nos. 3,
796,406; 3,813,107; and 3,832,438, the aforesaid patents being assigned to
the assignee of the present invention and issued on March 12, 1974, May 28,
1974 and August 27, 1974 respectively.
Figures 3a through 3c show the cast manhole base 30 provided by the
present divisional application resulting from the casting operation employing
the apparatus 10 of Figure 1, the cast manhole base 30 being comprised of a
base portion 31 and an integral, upwardly extending cylindrical shaped sidewall
32 terminating in a step-like ledge 33.
. 10 The sloping surfaces 14b and 14c of mold member 14 form the sloping
interior surfaces 34a and 34b of base member 30, the surfaces sloping downwardly
toward invert 35 formed by the substantially cylindrical shaped ~rojection 14d,
forming an integraL part of mold member 14. Surfaces 14b and 14c cause liquids
on surfaces 14b and 14c to run back into invert 35.
Flange portions 14e and 14f form and define the recesses 36a and
36b which are substantially semi-circular shaped recesses arranged between
the outer ends of invert 35 and the associated sidewall openings 38 and 39.
As can best be seen in Figure 3c, sidewall opening 38 has a tapered portion
38a which tapers inwardly toward gasket 17, and a tapered portion 38b which
tapers outwardly away from gasket 17 and which substantially merges with the
outward radial end 36a-1 of recess 36a. The D-shaped portion 17a of gasket
17 can be seen to have a hollow interior portion 17a-1~ which enables the gasket
to be compressed upon insertion of a connecting pipe. The gasket 17 serves
as a pipe-to-manhole seal. Joint assembly is quick and easy. The end 41a of
pipe 41, as shown in dotted fashion in Figure 3a, is coated with a suitable
lubricant and is pushed into the sidewall opening 38a. The gasket 17 provides
a compression-type joint with no moving parts and the simplicity of the joint
assembly eliminates both human error and the problems inherent in rigid joints.
The retainer rings 16, 16 hold the gaskets 17, 17 in a shape which precisely
- 14 -
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conforms to the curvaturc of the openings 38 and 39. Gaskets 17 provide a
positive watertight seal and, together with its associated recess, for example
recess 36a, provide at least 10 of omni-directional deflection of pipe 41
relative to the longitudinal axis 43 of the manhole base 35 provided by the
present divisional application. As is typical in the installation of the pipe
41, the end of the pipe 41 remote from end 41a is coupled to an adjacent pipe
after Eirst installing end 41a into manhole base 30. The pipe 41 is typically
arranged at an angle 0 relative to longitudinal axis 43 until its end 41a is
moved into sidewall opening 38 by an amount sufficient to cause its end remote
from end 41a to clear the end of the pipe (not shown) to which it is to be
subsequently joined, whereupon the pipe 41 may then be moved so that its
longitudinal axis 44 is brought into coincidence with longitudinal axis 43.
Thus, the recesses 36a and 36b provide the valuable function of facilitating
insertion of each pipe, e.g. pipe 41, into its associated sidewall opening,
e.g. opening 38.
The registration pins 14g and 14h which cooperate with the central
openings 16c in the gasket retaining assemblies 16, 16 assure precise align
ment between sidewall openings 38 and 39 and invert 35, thereby assuring smooth,non-turbulent flow of liquid matter as the liquid matter transfers from the
incoming pipe 41 to the invert 35 and from the invert 35 to the outgoing pipe
45. The casting operation described hereinabove also enables the manhole
base 30 provided by the present divisional application and the invert 35 to
be formed in a single operation and at the same site, preferably the factory
site, thereby significantly increasing productivity and reducing production
costs, as well as providing a more uniform product.
The casting apparatus described hereinabovc in connection with
Figures 1 through 3c is cxtrcmely advantageous for use in standardi~ed manhole
bases. For example, the manhole base 30 provided by the prescnt divisional
application shown in Figures 3a-3c has a linear invert 35 cxtcnding along an
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imaginary diameter 43 of the manhole base 30 provided by the present divisional
application. This invert configuration 35 is utilized in a vast majority of
applications making it practical to design and produce a mold member of the
type shown as mold member 14. However~ in situations where manhole bases
having non-standard sidewall openings and accompanying inverts are required
on a less frequent basis or in small quantities which do not warrant the
above mass production techniques, but nevertheless should be of the same
accuracy and precision design, an alternative design may be used in conjunction
with all of the techniques as will be described hereinbelow.
In order to form manhole bases provided by the present divisional
application in accordance with the single-pour technique provided by the
above identified parent application in which sidewall openings may be arranged
at angular orientations other than that shown in Figure 3b, the mold member
50 shown in Figures 12 through 12c may be used in place of the mold member 14
shown in Figures 1 and 2a through 2c.
Mold member 50 is comprised of body portion 52 having sloping side-
walls 52a and 52b similar to the sloping sidewalls 14b and 14c of mold member
14 shown, for example, in Figure 2a. The invert forming projection of mold
member 50 is comprised of a stationary portion 54 integrally joined to body
portion S2 and having a recess forming flange 56 at its outer end, flange 56
being substantially the same as flange 14f shown, for example, in Figure 2a.
The invert forming projection is further comprised of a movable
invert portion 58 of substantially cylindrical shape and having an outward
radial end provided with a recess forming flange 60 which is substantially the
same as flange 14e shown, for example, in Figure 2a. Flanges 56 and 60 are
designed to form the recesses such as, for example, thc recesses 36b and 36a
of manhole base 30, shown in Figures 3a-3d. Registration pins 62 and 64 are
reciprocally mounted in a manner similar to registration pins 14g and 14h of
mold member 14 shown, fcr examplc, in Figures 2a and 2b and are operated in
12~B~
a manner to be more fully describcd.
A sectional view of invert forming member 58 is shown in Figure 12a
and this invert forming member can be seen to be hollow and has a substantially
semi-oval shape. The lower edges 58a and 58b are positioned just above the
top surface of body member 52. Channel-shaped resilient sealing gaskets 66,
66, are fitted about the lower edges 58a, 58b, to provide a resilient mount
for supporting edges 58a, 58b on the top surface of body member 52 and to
prevent casting material from entering into the region between projection 58
and the top surface of body member 52. A supporting assembly comprised of
brackets 68a, 70, 72 and 74 have their outer ends secured to the interior
surface 58c of invert forming portion 58 and have their opposite ends secured
by suitable fastening means 76, 78 to a vacuum grip assembly 80 comprised of
a resilient, compressible, substantially bell-shaped member 82 and a pumping
assembly 84 having a reciprocating, manually manipulatable operating button
86 which, when repeatedly depressed and released, draws a vacuum in the interior
region defined by bell-shaped member 82 and the top surface of body portion
52, thereby firmly mounting invert forming member 58 upon the surface of
body member 52. The movable invert forming member 58 can thereby be seen to
be capable of being positioned at any suitable angle relative to invert forming
portion 54 and is capable of being swung about an imaginary central axis rep-
resented by dotted line 88, in either the clockwise or counter-clockwise
direction, as shown respectively by arrows A5 and A6. When it is desired to
release the invert forming portion 58 from body portion 52, release arm 90
of vacuum grip assembly 80 is depressed, rotating arm 90 in the clockwise
direction, as shown by arrow A6 about pivot pin 91, causing the vacuum condi-
tion to be interrupted and allowing air at atmospheric pressure to be intro-
duced into the hollow region between bell-shaped member 82 and the top surface
of body portion 50, thereby releasing the vacuum grip assembly 80 and hence
the invert forming portion 58 from body portion 52.
l~U~25
A sectional vicw of the invert forming portion 54 looking in the
direction of arrows 12b-12b, as shown in Figure 12b. The lower edges 54a and
54b are secured to the top surface of body portion 52 for example, by weld-
ments W, W. A flexible invert forming portion 94 is arranged to span between
invert forming portions 54 and 58 as can best be seen in Figures 12 and 12c,
and is preferably formed of a rugged cloth or cloth-like material 96 which
may be in the form of a wide band wrapped in an overlapping helical fashion
so as to embed a preferably continuous, helically-wound supporting wire 98,
to form flexible ducting 94 which, in most applications, is typically provided
with a circular cross-sectional configuration. The flexible ducting assembly
94 used in an embodiment of the invention provided by the above identified
parent application or provided by a first divisional application filed of even
date herewith, however, is provided with a substantially D-shaped cross-sec-
tional configuration defined by a generally semi-circular portion 94a and a
linear surface portion 94b, shown best in Figure 12b.
Both ends of flexible ducting assembly 94 are reinforced by D-shaped
reinforcing frames 100 and cooperating straps 102. Since both reinforcing
arrangements at both ends of flexible ducting 94 are substantially identical,
only one has been shown for purposes of simplicity. As shown in Figure 12b,
rigid D-shaped reinforcing frame 100 is positioned within the interior of
flexible ducting assembly 94 and ad~acent the right-hand end thereof (relative
to Figure 12). A linear strap 102 is positioned along the exterior surface
of planar surface portion 94b. Strap 102 and D-shaped reinforcing member 100
are retained in position by fastening assemblies 103 and 104 which secure
member 100 to member 102 and which sandwich the planar portion 94b of flcxible
ducting assembly 94 therebetween. The right-hand end 94c of flexible ducting
assembly 94 is preferably force-fittingly inserted into the hollow region
defined by the interior of the left-hand end 54d oE invert forming portion 54
and the top surface of body portion 53. As was described hereinabove, the
- 18 -
~. .
lZO !3C~
left-hand end 94d of flexible ducting assembly 94 is provid~d with a similar
D-shaped reinforcing member 100 and strap 102 and similarly is preferably
force-fittingly inserted between the interior surface of invert-forming portion
58 and the top surface of body portion 52. Obviously, if it is desired to
permanently secure flexible ducting portion 94 to invert forming portions 54
and 58, this may be accomplished for example, by providing suitable fastening
means.
Figure 12c shows an arrangement in which the registration pins 62
and 64 and the vacuum grip assembly 80 may be operated from a remote source.
As shown in Figure 12c, the manually operable vacuum grip assembly 80 is rep-
laced by a vacuum grip assembly 80' secured to the interior of invert forming
portion 58 by similar bracket means for example, by bracket member 68. Bell-
shaped member 82 is coupled to a remote vacuum/pressure source, (not shown
for purposes of simplicity) by means of conduit 107 to draw a vacuum in the
interior region defined by bell-shaped member 82 and the top surface of body
portion 52. The vacuum condition is selectively released by introducing air
of at least atmospheric pressure into the aforesaid hollow interior region
when it is desired to reposition invert forming portion 58.
~egistration pins 62 and 64 may be reciprocally operated to be selec-
tively moved in the directions shown by double headed arrows A8 and A9 bymeans of piston assemblies 110 and 112, each communicating with a remote
vacuum/pressure source (not shown) by means of a common conduit 114 communi-
cating with piston cylinders 110 and 112 by means of branch conduits 114a and
114b.
By introducing air under pressure into conduit 114, the piston members
llOa, 112a, are moved in the outward radial direction causing the piston rods,
which in actuality are registration pins 64 and 62, to move radially outward
for insertion into the cooperating central openings in the gasket rctaining
assemblies 16, 16 shown, for example, in Figure 1.
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lZ08~'~5
By coupling conduit 14 to a vacuum source, pistons 110a, 112a may
may be drawn radially inwardly and toward one another to draw pins 64 and 62
into the interior of the invert forming portions 58 and 54, thereby automating
these operations.
A manhole base provided by the present divisional application is
formed in accordance with the single-pour technique of an embodiment of the
invention provided by the above identified parent application and utilizing
the mold forming member 50, in a manner substantially similar to the technique
described in connection with the apparatus 10 of Figure 1 except that the
movable invert forming portion 58 is positioned at the desired angle relative
to invert forming portion 54. Flexible ducting assembly 94 is adapted to flex
and form a smooth curved portion intermediate the inner ends of invert forming
portions 54 and 58 thereby forming a continuous invert forming assembly defined
by portions 54 and 58, and the flexible ducting 94 arranged therebetween.
Once moveable invert forming member 58 is properly positioned, a
vacuum condition is drawn by the vacuum grip assembly 80, or 80', to firmly
secure invert forming portion 58 in the proper angular alignment relative to
stationary invert forming member 54.
Thereafter, the invert forming member 50 is positioned upon the
inner cylindrical mold member 18 shown in Figure la. in place of the mold
forming member 14. Obviously, the horizontally aligned wires 20b are bent
in the manner shown in Figure 1 at the proper angular orientations so as to
coincide with the positions occupied by the outer ends of invert forming mem-
bers 54 and 58. Thereafter, all of the mold forming steps are identical to
those described hereinabove in connection with Figure 1 to form a manhole base
provided by the present divisional application utilizing the single pour tech-
nique provided by the above identified parent application. The invert formed
thereby will be provided with two substantially linear invert portions 35'
and 35" and a curved, intermediate portion 35 " ', as shown best in the manhole
_ 20 -
~ZO~Z5
basc 30' provided by the present divisional application of Figure 3d. The
remaining advantagcous fcatures and characteristics of manhole basc 30' pro-
vided by the present divisional application are substantially identical to
those described in conncction with the manhole base 30 provided by the present
divisional application of Figures 3a through 3c.
The two pour techniquc provided by a first divisional application
filed of evcn date herewith may be employed in place of the single pour tech-
niquc provided by the above identified parent application and is further
uniquely advantageous for use in forming manhole bases provided by the present
divisional application having more than two sidewall openings. The first
stage of the two pour technique provided by a first divisional application
filcd of even date herewith is performed through the utilization of the casting
apparatus 10' of Figure 4 which is substantially identical to the casting
apparatus 10 of Figure 1, except that the mold member 14 provided in the
apparatus 10 of Figure 1 is not used in the two pour technique provided by a
first divisional application filed of even date herewith. More particularly,
outer cylindrical mold member 12 is shown positioned upon disc-shaped member
22. Inner cylindrical mold member 18, although shown in exploded fashion,
is also supported upon disc-shaped member 22 and is further provided with a
closed top surface 18d. Wire reinforcing frame 20 is likewise positioned
upon disc-shaped member 22 and the horizontally aligned wires 20b are bent
to form openings 20c and 20d to receive the gasket retaining assemblies 16,
16.
In the absence of the mold member 14, gasket retaining asscmblies
16, 16, are properly positioned and secured in the desired position by threaded
members T1, T2, which extend through openings 12d and 12e in outer cylindrical
mold member 12, in order to threadedly engage openings 16c, 16c which are
tappcd to provide a threaded engagement with threaded fastening members T1
and T2. The threaded fastening members are providcd with cnlarged flangc
- 21 -
s
portions Tla and T2a which rest against the exterior surface of outer cylin-
drical mold member t2 so that when tightened, the threaded ~asteners T1 and
T2 cause the adjacent edges of retainer members 16a, 16a, to be firmly urged
against the interior surface of outer cylindrical mold member 12. Once the
above-mentioned mold members of casting apparatus 10' are fully assembled,
the casting operation is begun. The manhole base is cast "upside-down". The
hollow interior region between the exterior surface of inner cylindrical mold
member 18 and the interior surface of outer cylindrical mold member 12 form
and define the sidewalls of the manhole base. The remaining interior region
between the closed end 18d of mold member 18 and the mdld member 12 extending
thereabove form and define the bottom of the manhole base.
After the casringmaterial has been poured into the mold apparatus,
the casting material is allowed to set. To facilitate the setting of the
casting material, the molding apparatus 10' may be covered with a housing or
shroud (not shown) for purposes of simplicity). Steam under pressure is then
introduced into the shroud to raise the temperature level of the casting
material and thereby accelerate the setting of the casting material.
Once the casting material has been set, hooks (not shown) coupled
to an overhead crane (not shown) are connected to chains 15a, 15a, to lift
the entire casting apparatus 10'. The apparatus 10' is lifted a distance
above the ground sufficient to allow the entire casting apparatus to be turned
"rightside-up", the casting apparatus being swung about the central axis of
collars 15, 15. After being turned over, the casting apparatus 10' is then
set upon the ground and threaded fasteners T1 and T2 are removad. The inner
and outer mold members are then removed and the fastening means (not shown)
coupling the gasket retaining members 16a and 16b of each gasket retaining
assembly 16 are removed to remove member 16a and 16b from each of the sidewall
openings which they form and define, thereby completing the casting operation.
_ 22 -
~Ithough the example of Figure 4 shows a molding apparatus for forming
a manhole base provided by the present divisional application having two side-
wall openings, it should be understood that three or more sidewall openings
may be formed throught he use of the apparatus 10' of Figure 4, and through
the use of additional gasket retaining assemblies 16 and threaded fastening
members T, as well as appropriate openings provided in the sidewall of outer
cylindrical mold member 12 to position and secure the gasket retaining members
at desired locations.
Figure 5 shows a manhole base 120 provided by the present divisional
application formed through the use of the molding apparatus tO' shown in
Figure 4, and being comprised of a bottom portion 122 and integral upwardly
extending sidewall 124 having openings 126 and 128, each provided with a resi-
lient compressible gasket 130 and 132, respectively. The step-like upper edge
134 is designed to receive and support a complementary step-like lower edge
of an intermediate or riser member of a manhole assembly (not shown), as is
conventional in manhole assembly technology.
The interior floor 136 of manhole base 120 is substantially flat
and is positioned well below the lower ends of the sidewall openings 126, 128.
The second phase of the two pour technique provided by a first
divisional application filed of even date herewith, i.e. the formation of the
invert, is performed through the use of the apparatus 140 shown in Figures 6
through 8b and comprised of an invert forming member 142 having a substantially
cylindrical shaped portion 142a, a planar upper surface 1~2b, having an elon-
gated flat bar 144 integrally joined thereto and having a substantially semi-
circular shaped recess forming Elange portion 142c provided at one end thereof
and adapted to form the recess arranged between the outer end of the invert
and the adjacent sidewall opening, such as for example the recesses 36a and
36b shown in Figure 3a, and the recesses to be described hereinbelow in con-
nection with Figure 10.
- 23 -
~Z~ 25
Flange portion 142c has a planar end surface 142d provided with a
tapped opening 142e which is coaxial with the longitudinal axis of semi-cylin~
drical portion 142a.
Dish-shaped registration member 146 forming part of the invert for-
ming assembly 146a and an integral flange 146b sloping outwardly therefrom.
The disc-shaped central portion 146a has a curvature conforming to the cur-
vature of gasket 17. A centrally located opening 146c is provided in disc-
shaped central portion 146a has a curvature conforming to the curvature of
gasket 17. A centrally located opening 146c is provided in disc-shaped por-
tion 146a.
Dish-shaped registration membcr 146 is press-fitted into opening
126, so that the cxterior surface of flange 146b rests upon tapered surface
126a of opening 126 and so that the marginal portion of disc-shaped central
portion 146a rests against the right-hand surface 17f and conforms with the
curvature of gasket 17.
An elongated threaded rod 148, also forming part of the invert for-
ming apparatus 140, is extended through opening 146c and threadedly engages
tapped opening 142e. The left-hand end of threaded rod 148 extends through
an elongated slot 150a in rigid elongated plate 150 which is positioned to
span opening 126 and rest against the exterior surface of sidewall 124. Elon-
gated threaded rod 148 has a length sufficient to extend through elongated
slot 150a. A butterfly fastener 152 is threaded on to the left-hand end of
rod 148 and is adequately tightened an amount sufficient to cause dish-shaped
registration member 146 to be pressed firmly against gasket 17 and to cause
invert forming member 142 to be tightly drawn against dish-shaped rcgistration
member 146.
Opening 146c is located along an imaginary axis 154 which is precisely
aligned with and passes through the center of opening 126, which is also the
center of gasket 130. Opening 142e in mcmber 142 is also coincident with
- 24 -
~LZ~ ;Z5
imaginary axis 154 which coincides with the longitudinal axis of the invert
forming portion 142a. By interconnecting all of the components of thc inv~rt
forming assembly 140 shown in Figure 6, precise alignment between the portion
of the invert formed by member 142 and sidewall opening 126 is simply and yet
positively assured.
An assembly substantially identical to the invert forming assembly
140 of Figure 6 is secured in place in each of the sidewall openings 126 and
128. Obviously in embodiments in which three or more sidewall openings are
provided, an apprpriate number of assemblies 140 is provided for each such
sidewall opening.
Figure 9 shows a manhole base 120' substantially similar to the man-
hole base 120 of Figure 5 and having three sidewall openings, each having an
invert forming assembly 140, 140' and 140 " mounted thereto in the manner
described hereinabove in connection with Figure 6.
In order to be assured that each of the assemblies 140 through 140 "
have their interior ends in the proper angular orientation and to further
assure that the invert forming members 142, 142' and 142 " are horizontally
aligned, i.e~. have their upper surfaces 142b, 142b' and 142b " lying in a
common imaginary horizontal plane, elongated rigid bars are clamped in place
to obtain such alignment. For example, Figure 6 shows an elongated rigid bar
156 bent at 156a so that two straight portions 156b and 156c Erom an angle
which angle is precisely the desired angle to be formed between the invert
forming portions so joined. Straight portion 156b is placed against elongated
projection 144 and with its lower edge 156b-1 resting against planar top sur-
face 142b. SuitabLe clamping means, such as, for example, the clamping means
C1 and C2, are utillzed to retain the portion 156b of bar 156 in position
relative to elongated projection 144 and hencc member 142. The remaining half
156c of bar 156 is placed against projection 14~l' of assembly 140' and resting
on surface 142b' and is similarly clamped into place by clamping members C3
- 25 -
iZ(~8~ 5
and C4. This technique assures that the top surfaces 142b and 142b' of mcmbcrs
142 and 142' lic in a common horizontal plane, further assuring precise align-
ment and accurate registration as between the invert to bc formed thercby and
the associated sidewall openings in the manhole base 120'.
Precise alignment and orientation of invert forming assembly 140 "
is accomplished in a similar manner by utilization of a bent bar 156' having
its linear portion 156a' clamped toprojcctio~ 144 " by clamping means C5 and
C6 and having its linear half 156b' clamped to projection 144' by clamping
means C4.
When the assemblies shown in Figure 9 are fully assembled and inter-
connected to one anotherin the manner described hereinabove, the casting
material is poured into the interior of manhole bsae 120 provided by the
present divisional application to fill the interior thereof to the proper
height. The sloping surfaces surrounding the invert are manually shape and
formed by operators as the casting material is poured into manhole base 120'
provided by the present divisional application. The center portion 160d of
the invert in the region of the gap G between the inner ends of the invert
forming assemblies 140, 140' and 140 " is manually formed by the operators
during the casting operation. After the casting material has been poured and
allowed to set, the assemblies 140, 140' and 140'' are disassembled and removed
from manhole base 120' provided by the present divisional application.
The completed manhole base 120 " provided by the present divisional
application is shown in Figure 10 as having an invert defined by three invert
portions 160a, 160b and 160c. The flanges such as, for example, the flange
portion 142c of Figures 6 and 8a, form the recess portions 162, 164 and 166
positioned between the outer end of each invert portion 160a, 160b and 160c
and the associatcd sidewall openin~ 168, 170 and 172 respectively.
Figures 6a and 6b show a clamping bar assembly 180 which may be
substituted for the clamping bar 156 shown, for example, in Figure 6. Thc
- 26 -
lZl~ 3;2~
clamping bar assembly 180 is comprised of cooperating members 182 and 184,
each being comprised of an clongated bar 182a, 184a and a dlsh-shaped coupling
member 182b, 184b respectively, each such cup-shaped member being provided
with a central opening 182b-1, 184b-1 for receiving fastening member 186 in
the form of a threaded bolt adapted to threadedly engage nut 188. The exterior
diagonally aligned surface portion 182b-2 of dish-shaped member 182b is knurled
or otherwise roughened and the interior diagonally aligned surface 184b-3 of
dish-shaped member 184b is likewise knurled or roughened and cooperates with
knurled surface 182b-2 to lock the dish-shaped members 182b and 184b together
when fastening members 186, 188 are suitably tightened. The dish-shaped
members 182b, 184b and hence the bars 182a, 184a, may be arranged at any
desired angular orientation in order to coincide with the angular orientation
of the invert forming members such as, for example, member 142 in order to
clamp the invert forming members at the proper angle. If desired, a marker
190 may be provided on dish-shaped member 182b and cooperating indicia may be
placed about the exterior diagonally aligned surface 184b--2 to cooperate with
marker 190 in order to facilitate setting of arms 182a, 184a at the desired
angular orientation.
Figure 11 shows a typical assembly 200 similar to the assembly 140
of Figure 6 and which may be employed to form an invert in a relatively large
size manhole base provided by the present divisional application, the assembly
200 of Figure 11 preferably being formed of a plastic material to minimize
production costs, aLthough any other suitable material mayhe employed if
desired. The most prevalent size manhole base typically is designed to acco~mo-
date a concrete pipe having an outer diameter of 2 feet or more. The invert
forming assembly 200 is designed to form an invert of a very large size dia-
meter and, as a result, is provided with a pair of dish-shaped registration
members 202, 204 each adapted to be positioned within the interior half of
a sidewall opening and having surfaces 202a, 204a arranged to rest against
- 27 _
3L21~B~
the tapered interior surface 126a of sidewall opening 126 (see Fig. 6) while
the outer marginal portion of surfaces 202b, 204b are designed to rest against
the surface 17f of gasket 17. As was described hereinabove, and especially
due to the large diameter of the sidewall opening, each sidewall opening, e.g.
sidewall opening 126, for example, has a curvature conforming to thc radius
of curvature of the manhole base gasket which conforms to the radius of cur-
vature of the manhole base sidcwall, such radius of curvature being measured
in a horizontal plane which is perpendicular to the sidewall of the manhole
base.
The invert defining members 206 and 208, similar to the invert
defining member described in connection with Figure 6, are each provided with
a planar top surface 206a, 208a having an elongated linear projection 210,
212 and having the outer ends thereof provided with flange portins 206a, 208a
for forming the aforementioned recesses arranged between the outer ends of
the invert and the associated sidewall opening. The substantially semicircular
shaped peripheries 206c, 208c form and define asssociated portions of the
invert within the manhole base provided by the present divisional application.
The invert fprming assembly 200 is mounted within a manhole base provided by
the present divisional application of the type shown in Figure 9 in a manner
substantially the same as and utilizing substantially the same apparatus as
the invert forming assembly shown in Figure 6. More specifically, cach dish-
shaped registration member 202, 204 is provided with a central opening 202c,
204c and, although not shown, the outer cnds of invert forming members 206
and 208 are likewise providcd with cooperating tapped openings Eor receiving
a threaded rod such as, for example, the threadcd rod 148 of Figure 6. Open-
ings 202c, 204c are coincident with the ccnter of the openings 126, 128 in
sidewall 124 (see Figure 5). The openings (not shown) provided in members
206 and 208 are coincident with the longitudinal axis of the invert to be
formcd. These centers arc simply and rapidly brought into prccise axial align-
- 28 -
3~
ment when the assembly 200 is mounted within manhole base 120 provided by
the present divisional application and Eixedly secured in place through the
additional means of the rigid plate 150 and fastener 152. As was described
hereinabove, the gap G between the inner ends of members 206 and 208 is formed
during the casting operation to conform to the shape of the invert by operators
who remove sufficient casting material to provide the desired shape of the
invert at the intermediate portion thereof. Similarly, the operators also
move and/or shape the casting material in the region on opposite sides of the
invert being formed to form surfaces 161a, 161b, 161c (see Figure 10) which
slope downwardly toward the invert in order to assure that any liquid falling
upon such sloping surfaces flows downwardly along the sloping surfaces to be
returned to the invert.
The horizontal alignment of the assembly 200 is obtained through
the use of a clamping member 180 and clamping assemblies C9 and C10, by clam-
ping member 180 to projections 210 and 212 in a manner described hereinabove
in connection with the embodiment of Figure 6. Forming the assembly 200 as
shown in Figure 11 of a suitable plastic material, e.g., synthetic polyester,
for example, greatly reduces production costs for producing assemblies 200
and yet provides apparatus which is sufficiently durable to withstand repeated
use.
As was the case with the mold structure employed in the single-pour
apparatus provided by the above identified parent application, the apparatus
shown, for example, in Figures 6 and 11 may be modified to provide an inter-
mediate flexible connector similar to that employed with the single-pour mold
forming apparatus provided by the above identified parent application shown
in Figure 12 and provided for use in conjunction with the two-pour technique.
For example, Figures 13 through 13b show invert forming apparatus 300 similar
to that shown in Figures 6 and 11 and comprised of invert defining members
302 and 304 having planar top surfaces 302a, 304a; substantially semi-cylindrical
- 29 -
invcrt forming surfaces 302b, 304b; elongated projcctions 302c, 304c; and
recess forming flanges 302d, 304d. The invert forming members 302 and 304
are preferably hollow. Noting, for example, Figure 13a, a portion of invert
~orming membcr 304 is shown therein and is providcd with an open inner end
304e. A portion 304a-1 of top surface 304a is removed in order to accommodate
the intermcdiate flexible coupling 306 comprised of a rugged and yet bendable
material such as a rugged fabric 306a which is wrapped in a substantially
helical fashion about a substantially helically wound wire reinforcement 306b
to form a flexible duct having a planar top surface 306c and a substantially
semi-cylindrical bottom surface 306d. The flexible ducting 306 is reinforced
in the same manner as the flexible ducting 94 shown, for example, in Figure
12b in that a D-shaped reinforcing duct 306. A strap 310 is placed along the
exterior surface of the planar portion 306d and fastening means 312 are util-
ized to secure D-shaped reinforcing frame 308 and plate 310, with the planar
section 306c of flexible ducting 306 sandwiched therebetween. Figures 13
through 13b show the manner in which the right-hand end of flexlble duct 306
is positioned within the left-hand end of member 304, with clamping plate 310
being positioned within the cutaway portion 304a-1 of planar top 304a. The
flexible 306 is preferably force-fitted within the interior of member 304 and
is further retained in place when clamping bar 314, which is arranged to engage
projection 304c and to rest upon the top surface 304a of member 304 also over-
]ies the top surface 306c of flexible ducting 306 and is clamped in position,
as shown for example, in Figure 13a so that bar 314 rests upon the surface
of plate 310 and thereby serves to retain thc Elexible ducting 306 in position.
The left-hand end of Elexible ducting 306 is positioned within member 302 in
a similar manner, plate 316 being positioned within a cutaway portion of top
surface 302a. The invert forming assembly 300 of Figure 13 is utili~cd in
conjunction with dish-shaped registration members such as, for example, the
dish-shaped members 320, 322 and 324, shown in Figure 14 as being arrangcd
- 30 -
within an associated sidewall opening within manhole base 326 providcd by the
prescnt divisional application. A threadcd rod of thc type shown as rod 148
in Figure 6 extends through central openings (not shown) provided within each
of the dish-shapcd registration members 320, 322 and 324 and threadedly en-
gages tapped openings (not shown) in the outcr ends of members 302 and 304,
which tapped openings are similar to the tapped openings 142e, for exas~nple,
shown in Figure 6. Clamping bars such as, for example, the clamping bar 328
is provided along the exterior surface of the manhole base sidewall 326a and
at each sidewall opening. Fastening means, such as, for example the fastening
member 152 shown in Figure 6 threadedly engages the aforementioned threaded
rod 148 and is tightened to firmly urge each dish-shaped registration member
320, 322 and 324 against the gasket 17 (see Figure 6) within the associated
side-wall opening. Figure 14 shows a manhole base 326 having three sidewall
openings and receiving assembly 300 shown in Figure 13 as well as an additional
assembly comprised of member 32 which is substantially identical to the mem-
bers 302 and 304.
A clamping bar 330 bent at the proper angular orientation is posi-
tioned upon ~lanar surfaces 302a and 304a so that it rests against projections
302c and 304c respectively. Clamping members, which have been omitted from
20 Figure 13 for purposes of simplicity, are utilized to secure clamping bar 330to projections 302c and 304c. A second clamping bar 334 which is bent at
the proper anglc is p]aced upon planar surfaces 304a and 332a o~ invert forming
members 304 and 332 and so that it rests against projections 304c and 332c.
Clamping bar 334 is likewise secured to projections 332c and 304c by suitable
clamping members of the type shown, for example, in Figure 11. The assemblies
300 and 332 shown in Figure 14 assure formation of an invert whose longitudinal
axis is in precise alignment with the center of each associated sidcwall opening.
I-lorizontal alignment of the membcrs 302, 304 and 332 is assurcd by the use
of the clamping bars 330 and 334, sccurcd in placc by thc atorementioned clamping
- 31 -
members such as, for example, the clamping members C9 and C10 shown in Figure
11. When the invert forming apparatus is fully assembled, the casting material
is poured into the interior of manhole base 326 to a levcl sufficient to form
the substantially T-shaped invert (160a, 160b, 160c - see Figure 10) defined
by members 302, and eliminates the need for removing casting material in the
region between the inner ends of members 302 and 304. Thus, when an invert
having three branchcs of the type shown in Figure 14 is to be formed (not also
Figure 10), casting material need only be removed in the gap region G between
the inner end of invert forming 332 and the adjacent sides of members 302 and
30~ and flexible ducting 306. The casting material is then allowed to set.
In order to expedite the setting operation, a shroud (not shown) may be placed
over the base member 326 and steam of a predetermined temperature and pressure
may be introduced into the shroud to elevate the temperature of the casting
material thereby expediting thesetting operation. ~uring casting, operators
move and shape the casting material to form sloping surfaces on opposite sides
on each of the invert portions to cause any liquid falling upon the sloping
surfaces to drain into the invert.
On,ce the casting material is set, the fasteners 152 (see Figure 6)
are removed to disassemble the invert forming assemblies which are then removed
from the manhole base 326 provided by the present divisional application,
yielding a manhole base provided by the present divisional application whose
invert is precisely aligned with the sidewall openings in the base member.
- 32 -
