U.S. patent number 3,707,990 [Application Number 05/105,266] was granted by the patent office on 1973-01-02 for concrete placement apparatus.
This patent grant is currently assigned to J. I. Case Company. Invention is credited to Wilbur G. Bennett, Bernard G. Braun, James F. Bremer, special administrator, Richard L. Brown, Aaron M. Schaible, deceased.
United States Patent |
3,707,990 |
Schaible, deceased , et
al. |
January 2, 1973 |
CONCRETE PLACEMENT APPARATUS
Abstract
A concrete placer including a boom supported for pivotal
movement on a horizontal pivot axis of a base with powered linkage
means for pivoting the boom on the base. The powered linkage means
includes a link having one end pivoted on the horizontal axis
through a fluid motor interposed between the base and the link. A
second fluid ram is pivotally connected to the link and the boom
and the powered linkage means is arranged so that the boom can be
pivoted about 180.degree. about the horizontal pivot axis. The boom
is of the articulated type having a plurality of sections with each
adjacent pairs of sections being pivotally interconnected and
having cooperating powered linkage means for pivoting adjacent
pairs of sections from an overlapping relation to a substantially
end-to-end relation. The boom sections support concrete
transmission means which includes a conduit for each of the boom
sections with the adjacent ends of the respective conduits
interconnected by end pieces having a portion located on the pivot
axis for the respective sections which accommodates pivotal
movement of the sections.
Inventors: |
Schaible, deceased; Aaron M.
(late of Rochester, WI), Bremer, special administrator; James
F. (Waterford, WI), Braun; Bernard G. (Waterford,
WI), Bennett; Wilbur G. (Terre Haute, IN), Brown; Richard
L. (Terre Haute, IN) |
Assignee: |
J. I. Case Company (Racine,
WI)
|
Family
ID: |
22304881 |
Appl.
No.: |
05/105,266 |
Filed: |
January 11, 1971 |
Current U.S.
Class: |
137/615 |
Current CPC
Class: |
B65G
53/52 (20130101); E04G 21/0436 (20130101); B60P
1/36 (20130101); E04G 21/04 (20130101); Y10T
137/8807 (20150401) |
Current International
Class: |
B60P
1/36 (20060101); E04G 21/04 (20060101); B65G
53/34 (20060101); B65G 53/52 (20060101); B67d
005/36 (); B67d 005/60 (); B67d 005/64 () |
Field of
Search: |
;137/615,565
;141/387,388 ;417/234,505,906 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cohan; Alan
Assistant Examiner: Wright; William H.
Claims
What is claimed is:
1. In a concrete placer, a boom supporting base rotatable about a
vertical axis; a boom having one end pivotally supported about a
horizontal axis on said base; a link having one end pivoted about
said horizontal axis; a first fluid ram having first and second
elements respectively pivotally connected to said base and said
link; and a second fluid ram having first and second elements
respectively pivotally connected to said link and said boom at a
location spaced from said horizontal pivot axis, said link and rams
being arranged so that extension of said rams pivot said boom
substantially more than 90.degree. about said horizontal axis.
2. A concrete placer as defined in claim 1, in which said second
ram is connected to said link adjacent an opposite end and said
first ram is connected to said link intermediate said ends.
3. A concrete placer as defined in claim 2, in which said first
fluid ram pivots said link between first and second positions and
defines an effective moment for said first fluid ram about said
horizontal axis the further improvement of the effective moment of
said first fluid ram being of substantially equal dimension in said
positions and being greater between said positions.
4. A concrete placer as defined in claim 1, in which said boom
includes at least two articulated sections having adjacent ends
pivotally interconnected and further including fluid linkage means
for pivoting said sections from an overlapping relation to a
substantially end-to-end relation.
5. A concrete placer as defined in claim 4, including the further
improvement of a concrete transmission conduit for each of said
sections; and means for interconnecting adjacent ends of said
conduits to accommodate pivotal movement of said sections.
6. A concrete placer as defined in claim 5, further including
releasable bracket means for interconnecting said conduits on the
respective boom section.
7. A concrete placer as defined in claim 6, in which said
releasable bracket means each, include first and second bracket
portions encompassing said conduits and pivotally interconnected on
one side thereof; and clamp means releasably connecting on opposite
sides of said portions.
8. A concrete placer as defined in claim 5, in which said conduits
are respectively located on opposite sides of associated sections
and in which said means for interconnecting said adjacent ends
includes first and second end pieces, each having a 90.degree. bend
and having one end cooperating with one of said conduits, said end
pieces having opposite ends with the axes of said opposite ends
aligned with the pivotal interconnection between said boom
sections.
9. A concrete placer as defined in claim 8, further including
flange means defining an enlarged recess on the opposite end of one
of said end pieces and an enlarged sleeve on the opposite end of
the other of said end pieces, said sleeve being received in said
recess; and ring means attached to said flange means, said ring
means overlapping said sleeve to interconnect said end pieces and
accommodate rotational movement about said pivot.
10. A concrete placer as defined in claim 1, in which said boom has
a longitudinal axis, and further including bracket means extending
to one side of said boom with said second element of said second
fluid ram pivotally connected to said bracket means at a location
spaced from said one side; and connecting means connecting said
bracket to said boom along the longitudinal centerline of said boom
so that forces transmitted from said second ram are transmitted to
said boom substantially along said longitudinal centerline.
11. A concrete placer as defined in claim 1, in which said boom
includes three sections with adjacent ends of said sections
pivotally interconnected; fluid linkage means cooperating with
adjacent sections to pivot adjacent sections from an overlapping
position to a substantially end-to-end position; and concrete
transmission means for said boom, said transmission means including
first, second and third conduits with the second conduit located on
one side of the second section and the first and third conduits
located on a side of first and third sections which is opposite
said one side of said second boom section; and means for
interconnecting adjacent ends of respective conduits, said last
means having a portion located on the pivot axis between respective
sections to accommocate pivotal movement of said sections.
12. A concrete placer as defined in claim 1, in which the
horizontal and vertical dimensions between the horizontal axis and
said pivotal connection between the base and the first fluid ram
are substantially equal, and the spacing between the pivotal
connections of said elements of said first fluid ram is less than
said dimensions when said link is in a first position.
13. A concrete placer as defined in claim 12, in which the spacing
between the horizontal pivot axis and the pivotal connection
between the first fluid ram and said link is substantially equal to
said dimensions and in which the spacing between the horizontal
axis and the pivotal connection between the link and the second
fluid ram is greater than said dimensions.
14. A concrete placer as defined in claim 1, further including a
platform supporting said base; and a plurality of extensible
outriggers depending from said platform, said platform and
outriggers being arranged so that said platform may be connected to
a frame of a vehicle.
15. A concrete placer comprising a base; a boom pivoted about a
horizontal axis on said base, said boom including a plurality of
boom sections with adjacent pairs of said sections being pivotally
interconnected, each boom section having opposed side walls;
powered linkage means for pivoting said boom on said base and
pivoting said sections relative to each other; and concrete
transmission means for said boom and including a separate rigid
conduit for each of said sections; one conduit for one boom section
of said pair being located on one side of the associated boom
section and the conduit associated with the next boom section being
located on the opposite side of the next boom section, each conduit
being separate from its associated boom section and being located
beyond the adjacent side wall; and means for interconnecting
adjacent ends of adjacent conduits, said last means including a
portion located on the pivot axes for the respective pairs of
section, said portion accommodating pivotal movement of said
sections.
16. A concrete placer as defined in claim 15, in which said last
means includes first and second end pieces for each pivotal
connection between the conduits of adjacent boom sections, each end
piece having a 90.degree. bend and one end connected to one
conduit; and means interconnecting the opposite ends of the first
and second end pieces for accommodating relative rotational
movement.
17. A concrete placer as defined in claim 16, in which said last
means each include flange means on one of said first and second end
pieces and defining an enlarged recess; a sleeve on the other of
said first and second end pieces and received in said recess; and
means for retaining said sleeve in said recess.
18. A concrete placer as defined in claim 16, further including
quick release bracket means for interconnecting said one end of
each end piece with a conduit, said bracket means each comprising
first and second bracket portions pivotally interconnected and
cooperating to encompass said conduit and said one end, and a
releasable clamp retaining said portions around said conduit and
said one end.
19. A concrete placer as defined in claim 15, further including a
platform supporting said base, a vehicle having a frame normally
supporting said platform; and a plurality of outriggers carried by
said platform, said outriggers being extensible to raise said
platform above said frame so that said platform may be attached to
said frame.
20. A concrete placer as defined in claim 16, in which said
connection between said one end of each end piece and a conduit
includes an enlarged portion on said one end and the adjacent end
of the conduit and bracket means encompassing said enlarged
portions.
21. A concrete placer as defined in claim 15, in which said powered
linkage means between said base and said boom includes a link
having one end pivoted about said horizontal pivot axis, a first
fluid ram interposed between said base and said link and a second
fluid ram interposed between said link and a first section of said
boom, said rams and link being arranged so that said boom may be
pivoted substantially 180.degree. about said horizontal axis.
22. A concrete placer as defined in claim 21, in which said second
fluid ram is pivotally connected to an opposite end of said link
and said first fluid ram is connected to said link intermediate its
ends.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to an apparatus for
conveying fluent materials, such as concrete.
With the recent emphasis on the use of concrete for high rise
building structures, various concrete pumps have been proposed for
transporting a plastic mass, such as concrete, to a level a
considerable distance above the ground. Such units are generally
disclosed in U.S. Pat. Nos. Re. 26,820; 3,327,641; and
3,494,290.
While pumping units of this type have proven satisfactory in
transmitting moist compressable materials to considerable heights,
difficulties have been encountered in utilizing such units
effectively since there was no manner of properly supporting the
necessary hosing required for transmitting the materials any great
distances. It will be appreciated that a material, such as
concrete, is extremely heavy and, when placed in columnar form in a
hose a height of more than 100 feet, appropriate supporting
equipment is necessary for the flexible hosing. While support
mechanisms for concrete have been proposed, see for example U.S.
Pat. No. 3,367,280 and 3,409,334, these supporting units have not
found any degree of commercial success because of the time and
energy required for varying the effective length of the supporting
unit.
SUMMARY OF THE INVENTION
The present invention contemplates a concrete placement unit which
includes an articulated boom that has a base section which is
capable of being pivoted substantially 180.degree. about a base
with the base in turn capable of being rotated substantially
360.degree. about a vertical pivot axis. The boom of the pumping
unit of the present invention is constructed in a manner that the
effective length thereof can readily be changed while concrete is
being transmitted through the unit.
The concrete placer of the present invention includes a boom
supporting base rotatable about a vertical pivot axis on a platform
with a boom pivoted at one end about a horizontal axis on the base
by powered linkage means. The powered linkage means includes a link
having one end pivotally supported on the horizontal axis and first
and second fluid rams respectively interposed between the base, the
link and the boom. The fluid rams and link are arranged in a manner
that the boom can be pivoted more than 90.degree. about the
horizontal axis.
The boom, forming part of the concrete placer of the present
invention, is of the articulated type and includes a plurality of
boom sections with each pair of sections interconnected at adjacent
ends for pivotal movement from a substantially overlapping position
to a substantially end-to-end position. The means for pivoting the
boom section relative to each other again includes powered linkage
means having opposite ends connected to the respective
sections.
According to another aspect of the invention, the boom supports
concrete transmission means which is capable of having concrete
transmitted therethrough while the boom sections are moved relative
to each other. The concrete transmission means including a conduit
for each of the plurality of boom sections and interconnecting
means for adjacent ends of the respective conduits with the
interconnecting means having a portion located on the pivot axis
between adjacent pairs of sections. The interconnecting means
include first and second end pieces each having a 90.degree. bend
therein and portion of each end piece is located on the pivot axis
between the sections. One end of each of the end pieces is
connected to one of the conduits by releasable bracket means while
the opposite ends of pairs of end pieces are interconnected to
accommodate relative rotational movement of the respective ends.
More specifically, the means for connecting the opposite ends of
the respective end pieces includes flange means on one of the end
pieces which defines an enlarged recess and a sleeve on the other
of the end pieces with the sleeve being received in the enlarged
recess and retained therein by a ring having a portion overlying a
portion of the sleeve and the flange and being connected to the
flange. Additionally, the connection between the end pieces and the
respective conduits incorporates a quick-release connection so that
the end piece can be readily separated from the conduit for
cleaning either the end piece or the conduit.
The entire placement unit is constructed and arranged so that the
unit may be attached to the frame of a conventional transporting
unit or vehicle, such as a truck, after the unit has been assembled
and is ready for use.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF DRAWINGS
FIG. 1 is a side elevation view of a concrete placer of the present
invention supported on a transport vehicle;
FIG. 1a is a side elevation of the boom in a collapsed
condition;
FIG. 2 is a fragmentary plan view of a portion of the concrete
transmission means;
FIG. 3 is an enlarged fragmentary view of the power linkage for the
boom on the base;
FIG. 4 is an enlarged fragmentary sectional view taken generally
along line 4--4 of FIG. 2;
FIG. 5 is a section view taken generally along line 5--5 of FIG.
4;
FIG. 6 is an enlarged fragmentary sectional view showing the
releasable bracket means for interconnecting conduit sections;
and
FIG. 7 is a sectional view taken generally along line 7--7 of FIG.
6.
DETAILED DESCRIPTION
While this invention is susceptible of embodiment in many different
forms, there is shown in the drawings and will herein be described
in detail one specific embodiment, with the understanding that the
present disclosure is to be considered as an exemplification of the
principles of the invention and is not intended to limit the
invention to the embodiment illustrated.
FIG. 1 of the drawings discloses a concrete placement unit,
generally designated by the reference numeral 10. The concrete
placement unit 10 is illustrated as of the self-propelled type and
includes a vehicle, generally designated by the reference numeral
12, having a frame 14 supporting the various parts of the concrete
placer. The concrete placer 16 includes a concrete pumping unit 16
and a concrete placement unit, generally designated at 20. Since
the concrete pumping unit 18 forms no part of the present
invention, no detailed description thereof appears to be necessary.
However, for purpose of completeness, U.S. Pat. No. 3,494,290
assigned to the assignee of the present invention, is incorporated
herein by reference and discloses a concrete pumping unit which may
be used with the present invention.
The concrete pumping unit 18 delivers concrete to an outlet conduit
22 which is connected to the placement unit 20 through a flexible
conduit 24.
The placement unit 20 includes a base 30 supported for rotational
movement about a vertical axis on a turntable 32 which is secured
to the upper surface of the platform 34 and a boom 36 is supported
for pivotal movement about a horizontal axis 38 on the base 30. The
platform has a plurality of extensible outriggers 39 depending
therefrom. The platform and outriggers are arranged so that the
entire placement unit 20 can be attached directly to the frame or
chassis of a commercial truck, such as any 24,000 GVW or larger,
without any modification of the chassis. This arrangement is of
considerable importance since it reduces the overall cost of a
self-propelled concrete placer.
According to one aspect of the present invention, the concrete
placement unit 20 includes powered linkage interposed between the
base 30 and the boom 36 for pivoting the boom substantially more
than 90.degree. about the horizontal pivot axis 38 on the base 30.
Such an arrangement considerably increases the versatility of the
unit.
The powered linkage means 40 includes a link 42 having one end
pivoted about the pivot axis 38 for the boom 36. A first fluid ram
44 has its cylinder 46 pivotally secured at 48 to an extension of
the base 30 while the piston rod 50 has its free end pivotally
connected at 52 to the link 42. The powered linkage 40 further
includes a second fluid ram 54 having its cylinder or first element
56 pivotally connected at 58 to the free end of the link while the
piston rod or second element 60 of the ram is connected through a
bracket 62 to the boom 36 at a location spaced from the pivot
38.
An inspection of FIGS. 1 and 1a reveals that the bracket 62 has a
cradle portion (not shown) which has arms located on opposite sides
of the boom and welded to the boom with spacer tubes 63 extending
through the boom sides and the arm and welded to the arms to
prevent collapsing of the boom section. The advantage of the
bracket connection at the center of the boom rather than the bottom
side of the boom is that the inner end of the moment arm, defined
by the bracket 62, for the ram 54, is at the center of the boom.
This arrangement allows greater loads to be applied to the bracket
without breaking the connection.
Referring particularly to FIG. 3, it will be noted that the pivotal
connection 52 of the first fluid ram 44 to the link 42 is at a
position intermediate the pivotal connection 38 of the link to the
base 30 and the pivotal connection 58 of the second fluid ram to
the link 42. FIG. 3 also shows that the horizontal spacing between
the pivotal connection 38 and 48 is defined by a dimension A while
the vertical spacing between these pivots is defined by a dimension
C. Also, the spacing between pivots 38 and 52 is defined by a
dimension B while the spacing between pivots 38 and 58 is defined
by a dimension D which is greater than the dimension B.
Additionally, the spacing between the pivotal connections 48 and 52
of the respective elements of the first fluid ram 44 defines a
dimension E.
Applicants have determined that the particular dimensions between
the various pivot points and the algebraic relationship of these
dimensions to a large measure determines the successful operation
of the fluid powered linkage means. Thus, according to a specific
aspect of the present invention, the dimensions A, B, and C are
substantially equal while the dimension E is less than either of
these dimensions, on the order of one-half of the A, B, or C. In
addition, the dimension D is substantially greater than the
dimension B and is on the order of 1.5 times the dimension B.
By selecting the dimensions as described above, the effective
moment arm for the first fluid ram will be substantially the same
for both extreme positions of the link 42. In addition, the
effective moment arm will be greater between the extreme positions.
Also, the selection of the dimensions A, B, C and E, as well as the
length of stroke of the fluid ram 44 will have the link 42 pivoted
approximately 90.degree. about the pivot axis 38 as the link is
moved from one extreme position to the other. The respective
positions of the link are shown in the solid and dotted line
positions of FIG. 3.
With the selection of dimensions as described above, the effective
moment arm for the fluid arm 44 will be approximately the same for
each extreme position of the link 42 so as to be capable of
applying substantially the same forces to the boom during
retraction of fluid ram 44 as is available during the
extension.
Additionally, after the link 42 has been moved to the second
extreme position shown by the dotted lines of FIG. 3, the second
fluid ram 54 may likewise be extended to pivot the boom
substantially 180.degree. from the first or right-hand position
shown in FIG. 3. Furthermore, the position of the link 42 will be
such that the maximum moment arm for the second fluid ram will be
available as the boom passes across the vertical axis defined by
the turntable 32.
According to another aspect of the present invention, the concrete
placement boom 36 is of the articulated type and preferably
includes three sections, with adjacent pairs of sections having
their adjacent ends pivotally interconnected and capable of being
pivoted from a substantially overlapping, shown in FIG. 1a, to a
substantially end-to-end relationship. The articulated boom vastly
increases the versatility of the entire unit and greatly increases
the performance of the concrete placing device 10.
Particular reference to FIGS. 1 and 1a the boom 36 includes a first
or base section 36a, a second or intermediate section 36b and a
third or outer end section 36c. The sections 36a and 36b have
adjacent ends pivotally interconnected at 70 and are moved from a
substantially overlapping position shown in FIG. 1a, to a
substantially end-to-end position by fluid powered linkage means
72. An inspection of FIG. 1 shows that the powered linkage means
includes a fluid ram 74 having its cylinder 76 pivotally connected
to the bracket 62 at 78 and its piston rod 80 connected to the
pivotal connection 82 of a compound linkage including links 84 and
86. The free ends of the respective links 84 and 86 are pivotally
connected to the boom sections 36a and 36b at locations spaced from
the pivot 70. With this arrangement, a single fluid ram may be
utilized to pivot the base and intermediate sections substantially
180.degree. from an overlapping position to a substantially
end-to-end position.
The intermediate or second boom section 36b is likewise pivotally
connected to the boom section 36c by a pivotal connection 90 and
again includes fluid powered linkage means 92 similar to linkage
means 72 so that the outer end section 36c may be pivoted from an
overlapping position shown in FIG. 1a to a substantially end-to-end
position shown in FIG. 1.
According to another aspect of the present invention, a concrete
placement unit 20 includes a fluid transmission means which is
completely separated from the boom 36 and which is capable of
continuously transmitting concrete therethrough while the various
boom sections are pivoted relative to each other. This arrangement
of course allows for greater versatility of the machine since it is
not necessary for the operator to discontinue the flow of concrete
while the unit is being repositioned to supply concrete to a
different location. For example, if a wall of a building were being
poured, a skilled operator could readily manipulate the boom so as
to traverse the entire length of the wall while concrete was
continuously being delivered through the concrete transmission
means.
The concrete transmission means includes a conduit for each of the
boom sections and means for interconnecting the adjacent ends of
the conduits to accommodate pivotal movement of the sections by the
powered linkage means 72 or 92. Thus, with particular reference to
FIGS. 1 and 2, the concrete transmission means includes a conduit
100 extending substantially the entire length of the outer end boom
section 36c, a second conduit 102 extending substantially the
entire length of boom section 36b and a third conduit 104 extending
substantially the entire length of the first boom section 36a. The
respective conduits 100, 102 and 104 are supported on the
associated boom sections by brackets 108, which may be of the
two-piece type encompassing the associated conduit.
The concrete transmission means further includes interconnecting
means 110 for connecting adjacent ends of respective pairs of
conduits and accommodating pivotal movement of the boom sections.
The interconnecting means is more clearly shown in FIG. 2 and
includes first and second end pieces 112 each having a 90.degree.
bend therein. One end of each of the end pieces 112 is releasably
connected to one end of a conduit by releasable bracket means 114,
which will be described in more detail hereinafter. The opposite
ends of the respective end pieces 112 have their axes aligned with
the pivot axis between the respective boom sections, e.g. sections
36b and 36c, with means 116 interconnecting the opposite ends of
the end pieces for accommodating relative rotational movement when
the associated boom sections are pivoted relative to each
other.
The interconnecting means 116 for the opposite ends of the two end
pieces is more clearly shown in FIGS. 4 and 5 and includes flange
means 120 fixedly secured to the end of one of the end pieces 112,
as by welding. The flange means defines an enlarged recess 122 for
receiving a sleeve 124 fixedly secured to the other end piece 112.
The interconnecting or coupling means 116 further includes a
retaining ring or means 126 for retaining the sleeve 124 in the
recess 122. An inspection of FIG. 5 will show that the means 126
has portions overlying the sleeve 124 and the flange 120 and is
fixedly secured to the flange by a plurality of circumferentially
spaced bolts 128. The sleeve 124 further has an end portion 130 of
reduced diameter to define a further recess for receiving an O-ring
132 and a backup ring 134.
Thus, the flange means 120 and the sleeve 124 cooperate to
accommodate relative rotational movement of the end pieces 112
while the associated boom sections are pivoted relative to each
other. The particular interconnecting means 116 is designed to be
capable of having concrete transmitted therethrough while the
associated boom sections are pivoted relative to each other. This
feature is of extreme importance in increasing the efficiency of
the overall machine since it eliminates the necessity of
discontinuing the pumping of concrete while the boom is
repositioned.
An inspection of FIG. 2 reveals the conduit 102 is located on one
side of the intermediate boom section 36b while the conduits 100
and 104 are located on the opposite sides of the outer and inner
boom sections 36c and 36a. Furthermore, the connections between
adjacent ends of the respective conduits, while having a portion
aligned with the pivots 70 and 90, do not form any part of the
structure defining the respective pivotal connections for the boom
sections.
According to a further aspect of the present invention, each of the
bracket means 114 are of the quick release type so that each of the
end pieces 112 can readily be disconnected from the associated main
conduit in instances when it is necessary to remove an end piece or
a conduit because it is plugged with concrete. It will also be
appreciated that such an arrangement considerably reduces the time
required for removing and replacing any of the boom sections or end
pieces.
The releasable bracket means 114 is shown more clearly in FiGS. 6
and 7 and includes circumferential recesses 140 in the periphery of
the conduits, e.g. 100 and 112, adjacent the ends thereof that
receive respective legs 141 of a bracket which includes a first and
second bracket portions 142 and 146 pivotally interconnected at
148. A sealing gasket 147 is received in each of the bracket
portions 142 and 146 and the opposite ends of the bracket portions
142 and 146 are releasably connected by a releasable clamp 150
which normally locks the two portions 142 and 146. When locked
together, the two portions emcompass the conduits 100 and 112 with
the gaskets 147 engaging the periphery of the conduits adjacent the
free ends to provide a fluid seal. However, the releasable clamp
150, can readily be opened by manipulation of a handle 154 so that
the bracket portion 146 can be pivoted about pivot 148 to
accommodate removal of either the end piece conduit 112 or the main
conduits 100, 102 or 104.
The concrete placement unit 10 of the present invention, is an
extremely compact unit in its collapsed condition (shown in FIG.
1a) and can be readily transported from one worksite to another
over most major highways or other surface roads. When the unit
arrives at a worksite, the boom or placement unit of the device can
readily be manipulated into an operative position in a matter of
minutes and will be ready for pumping concrete to various levels
and different locations at the worksite without the necessity of
assembling various sections as was heretofore necessary in
placement units of the type disclosed in U.S. Pat. Nos. 3,367,280
and 3,409,334. It will be noted that the present concrete placement
unit 20 of the invention is constructed in a manner that the
concrete transmission means is completely separate from the boom
structure and the rigidity of the boom structure is not in any way
dependent upon any portion of the concrete transmission line. For
example, the entire concrete transmission means could readily be
removed from the boom structure and boom structure could be
utilized for other purposes.
* * * * *