U.S. patent number 3,789,869 [Application Number 05/220,188] was granted by the patent office on 1974-02-05 for fire-fighting apparatus and elongate cantilever boom assembly therefor.
This patent grant is currently assigned to Snorkel Fire Equipment Company. Invention is credited to Carrol V. Morris.
United States Patent |
3,789,869 |
Morris |
February 5, 1974 |
FIRE-FIGHTING APPARATUS AND ELONGATE CANTILEVER BOOM ASSEMBLY
THEREFOR
Abstract
An elongate cantilever boom assembly. The assembly is fabricated
from identical U-shaped extrusions. The web is thicker than the
legs of the extrusion so that when the extrusions are welded
together the webs which are positioned at the extreme fiber have
the greatest stress resistance to provide a strong, lightweight
boom. The legs define tongue and groove means, one leg defining a
tongue and the other the groove so that a pair of such extrusions
from a single die may be juxtaposed in tongue and groove engagement
for welded securement.
Inventors: |
Morris; Carrol V. (St. Joseph,
MO) |
Assignee: |
Snorkel Fire Equipment Company
(St. Joseph, MO)
|
Family
ID: |
22822432 |
Appl.
No.: |
05/220,188 |
Filed: |
January 24, 1972 |
Current U.S.
Class: |
137/351; D12/13;
137/615 |
Current CPC
Class: |
B66C
23/701 (20130101); B66C 23/64 (20130101); Y10T
137/8807 (20150401); Y10T 137/6881 (20150401); A62C
31/24 (20130101) |
Current International
Class: |
B66C
23/64 (20060101); B66C 23/00 (20060101); B66C
23/70 (20060101); B66f 009/06 () |
Field of
Search: |
;137/344,615,351
;138/157,163,171,172 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Scott; Samuel
Claims
1. A mobile apparatus comprising a mobile frame and an elongate
hollow cantilever boom, said boom having a very substantially
greater length than transverse dimension, a first extruded elongate
boom section comprising a central web and a flange integrally
formed with said central web at each transverse edge of said
central web, a continuous portion of said central web across its
width being greater in thickness than the thickness of said
flanges, each of said flanges providing means at their free
longitudinal edges for engagement with a second extruded boom
section, a second extruded elongate boom section comprising a
central web and integral mating means secured to said engagement
means, welds securing said engagement means and said mating means
to each other at said free longitudinal edges, and means for
mounting said boom on said frame for
2. A mobile apparatus in accordance with claim 1 wherein said
central web
3. A mobile apparatus in accordance with claim 1 wherein said boom
is substantially rectangular in transverse cross-section and said
first boom
4. A mobile apparatus in accordance with claim 3, wherein said
first and second boom sections are substantially identical, and
said welds extend
5. A mobile apparatus in accordance with claim 4 wherein said
engagement means and said mating means are tongue and groove means
and one of said flanges providing a tongue means at its free edge
and the other of said flanges providing a groove means at its free
edge, each juxtaposed with a
6. A mobile apparatus in accordance with claim 4 wherein said
engagement means of each boom section comprises a tongue at the
longitudinal edge of one flange and a groove means at the
longitudinal edge of the other flange, said tongue and said groove
means being complementary, whereby said substantially identical
boom sections are in tongue and groove engagement with each other,
said welds holding said boom sections with
7. A mobile apparatus in accordance with claim 1 wherein said
apparatus is a fire-fighting apparatus and said cantilever boom is
mounted on said frame for movement relative to the frame about both
a horizontal and a vertical axis, said boom being mounted at one
end and being free at the
8. A mobile apparatus in accordance with claim 7 wherein said boom
mounts water discharge means at its free end and conduit means for
supplying
9. A mobile apparatus in accordance with claim 7 wherein said boom
member is substantially rectangular in transverse cross-section and
said first
10. A mobile apparatus in accordance with claim 9 wherein said
first and second boom sections are substantially identical, and
said welds extend
11. A mobile apparatus in accordance with claim 9 wherein said
engagement means and said mating means are tongue and groove means,
one of said flanges providing a tongue means at its free edge and
the other of said flanges providing a groove means at its free
edge, each juxtaposed with a
12. A mobile apparatus in accordance with claim 7, further
comprising a second boom member, said second boom member being
mounted on said first
13. A mobile apparatus in accordance with claim 12 wherein said
first boom member telescopically receives said second boom member
for telescopic movement with respect thereto.
Description
A wide variety of heavy duty construction equipment and the like
utilizes elongate, hollow, load bearing cantilever boom assemblies.
In such equipment, a cantilever boom assembly is secured at one end
to a support, usually for movement with respect to the support.
Such booms are then stressed in use, as by applying vertical loads
to the free ends of the boom.
A usual mode of fabricating booms of that character entails the
bending or folding of elongate steel plates into desired shapes,
such as a box-like shape or U-shaped sections, which are then
finished as necessary, as by welding. The use of folded shapes
means, of course, that all portions of the folded shapes will have
about the same strength or load bearing characteristics. To vary
the load bearing characteristics of such booms, thereby to minimize
the weight of the boom, it has been necessary to add additional
pieces, as additional elongate plates, at particular locations,
thereby to strengthen those portions of a boom assembly. Other
efforts to adjust the distribution of stresses in cantilever beams
have been suggested, as for example in Morton et al U.S. Pat. No.
3,572,528.
It has now been discovered that the complexities and disadvantages
of prior art practices may be avoided by the fabrication of
elongate hollow booms from appropriately dimensioned aluminum
extrusions, which extrusions are integrally formed with a plurality
of legs, a continuous portion of at least one of which is greater
in thickness across its width than the other legs. Preferably the
continuous portion extends across the entire width whereby the leg
and the continuous portion thereof are coincident in width. By so
forming elongate boom sections, when assembled into a cantilever
boom, a larger mass of material is positioned at the extreme fiber
of the boom, i.e., at the location where the greatest stresses will
be encountered. Not only does that eliminate subsequent
strengthening operations, as by the addition of reinforcing plates
or the like, but it also makes it possible initially to form a boom
section which will be of the lightest possible weight to satisfy
design requirements. That is because the alternative to adding
reinforcing plates or the like is to fold a boom section from a
plate which is thick enough to withstand the anticipated stresses
at the extreme fiber.
By fabricating a boom of extruded aluminum sections having legs of
different thicknesses, by a difference of at least about 10
percent, other advantages, beyond weight reduction and simplicity
of formation, also result. For example, during extrusion it is
possible also to form pre-shaped, weld preparation joints. Indeed,
it has been determined that pre-shaped weld preparation joints of
the tongue and groove type may readily be formed as a boom section
is being extruded. When a cantilever boom assembly is to be formed
as from two U-shaped sections and tongue and groove formations have
been formed at alternate edges of the legs of the U-shaped
sections, a pair of such sections may be disposed in tongue and
groove engagement with each other to mate and interlock, after
which they may be welded together. That arrangement of tongue and
groove formation makes it possible to use only one extrusion die to
form both of the sections to be used in fabricating a boom.
Furthermore, when identical U-shaped sections are used, and the
central legs of the "U" are the portions of greatest thickness, the
welds will be located at the neutral axis, i.e., at about the
center of the boom sides where the tensile and compressive stresses
in the cantilever boom in use are at a minimum.
Although booms constructed in accordance with this invention have
applicability in a wide variety of heavy duty equipment, they are
especially useful where minimum boom weight, dimensional accuracy
and appearance are important factors, such as in fire-fighting
equipment. Booms in accordance with this invention may be much more
accurately dimensioned throughout their entire lengths, than those
which are folded from plates, or the like. Further, because tongue
and groove formations may be integrally formed, they may be more
precisely located, and a minimum number of boom sections may be
more easily and precisely juxtaposed and aligned for securement by
welds in the assembly of the boom.
It has also been determined that when matching extruded U-shaped
boom sections are joined, the resulting boom is straighter and
freer of twists than booms which are assembled from folded material
or from a multiplicity of component parts. Furthermore, booms
constructed in accordance with this invention present a more
uniform and neater appearance, a factor which is of great
importance in some applications, such as in fire-fighting
equipment.
These and further objects, advantages and features of this
invention will become apparent from the following description and
drawings, of which:
FIG. 1 illustrates a typical fire-fighting truck, with which a boom
assembly of this invention is adapted for use;
FIG. 2 is an enlarged fragmentary view of the boom assembly of FIG.
1;
FIG. 3 is a cross-sectional view taken substantially along line
3--3 of FIG. 2;
FIG. 4 is an enlarged view of a portion of FIG. 3;
FIG. 5 is an enlarged fragmentary exploded view of a joint assembly
of FIG. 3; and
FIG. 6 is an enlarged fragmentary view of a portion of FIG. 3.
Referring now to the drawings, a telescopic, cantilever boom
incorporating the present invention is illustrated in its entirety
at 10 in FIG. 1. In FIG. 1, the cantilever boom 10 is depicted in a
retracted position on a mobile support which is illustrated as
being a pumper truck 12. Pumper truck 12 may be of a conventional
design, and desirably includes suitable control means (not shown)
by which a fireman may remotely control the boom 10 for discharge
of a controlled spray of water onto a fire. The support includes a
turntable 14 mounted at the rearward end of the truck 12. Turntable
14 mountingly supports the boom assembly 10 at one end for
rotational movement about a vertical axis. The turntable 14 may be
of the type disclosed in U.S. Pat. Nos. 3,346,052 and
3,599,722.
As is explained in those patents, turntable 14 may also mount the
boom for oscillatory movement about a horizontal axis 16. Movement
about axis 16 is provided by a suitable hydraulic cylinder means 18
which is connected at one end to the turntable 14 and at the other
end to anchor plate means 20 suitably secured to the boom 10.
The outer free end of boom 10 provides a suitable monitor assembly
22 which includes a discharge nozzle 24 through which water may be
discharged in desired volumes and patterns, as in the ways
disclosed in the aforementioned patents.
The boom 10 may be constructed and assembled in a manner similar to
that boom assembly which is described in commonly assigned,
copending U.S. Pat. Application Ser. No. 83,925 filed on Oct. 26,
1970, now U.S. Pat. No. 3,675,721, issued July 11, 1972, and
desirably includes suitable water supply or conduit means 26 which
are supplied with water from adjacent turntable 14. At their other
ends, conduit means 26 communicate with monitor assembly 22 so that
water may be discharged through nozzle 24. The disclosure of said
application Ser. No. 83,925 is here incorporated by reference.
Boom 10, as stated, may be constructed and may be operated
generally in accordance with application Ser. No. 83,925, except
that the boom members themselves, and particularly the outer or
lower boom member, are made and assembled in accordance with the
invention herein disclosed.
Referring now to FIGS. 2 to 6, boom assembly 10 comprises an
elongate lower outer boom member 30 and an elongate upper inner
boom member 32, each of which is generally rectangular in
transverse cross-section and each of which is hollow. Each is very
substantially longer than any dimension in transverse
cross-section. Boom member 32 is mounted for telescopic movement in
boom member 30.
Boom member 30, as best seen in FIGS. 3 and 4 comprises a pair of
identical elongate outer boom sections 34, 34', each of which is
generally U-shaped in cross-sectional configuration, and each of
which comprises a central web 36 and a pair of integral flanges 38
extending substantially at right angles to central web 36. Flanges
38 are disposed at the transverse edges of the central web 36.
Each boom section 34, 34', in the embodiment illustrated, is
extruded from a high strength aluminum alloy through a single
appropriate extrusion die and the finished cross-section is
integrally formed at the time the sections are extruded. By
extruding sections 34, 34', a multiplicity of conventionally
necessary fabrication steps are eliminated. Most importantly,
however, by extruding sections 34, 34' properly proportioned
integral leg and flange portions are provided, thereby to position
the greatest mass of material at the zones which are subject to the
most severe stresses, i.e., the boom section portions at the
extreme fiber. In the embodiment illustrated the zones subjected to
the greatest stresses in use are the upper and lower webs 36 of the
rectangular boom member 30.
As such, as best illustrated by FIG. 4, the thicknesses A of
central webs 36 are greater across their entire widths than are the
thicknesses B of the flanges 38 save only at the free longitudinal
edges of the flanges. At those edges, the flanges 38 provide
appropriately configured joint members. The joint members desirably
comprise a first tongue joint member 40 and a second groove joint
member 42 which are complementary in configuration. When the
U-shaped sections 34, 34' are provided with a tongue joint member
40 adjacent one flange edge and a complementary groove joint member
42 adjacent the other flange edge, a pair of identical boom
sections 34, 34' with opposite joint members in engagement with
each other may be juxtaposed for securance to each other. As such,
only a single extrusion die to form both of the sections necessary
to the formation of a rectangular boom member 30 is required.
When sections 34, 34' are juxtaposed with each other, i.e., are
positioned in the interlocking tongue and groove engagement
illustrated in the drawings, they are in alignment for securance to
each other, as by welding. When so juxtaposed, the flange ends
define an appropriately sized and configured weld preparation joint
or fillet 44 which is adapted to receive weld material 46. FIG. 5
illustrates an exploded view of the joint members 40, 42 and FIG.
6, at the left, illustrates the interlocked, aligned and welded
joint, with the weld material 46 filling fillet 44, thereby
permanently securing sections 34, 34' to each other. It is to be
noted that welds 46 are located at the neutral axes of boom member
30 so that they do not adversely affect the designed strength
characteristics at the extreme fibers, i.e., the central webs 36
which are subjected to the greatest tensile and compressive
stresses.
Although the individual U-shaped sections 34, 34' are quite
flexible and easily twisted when separate, when held in true
alignment at the time they are juxtaposed and welded together, they
provide boom members which are much straighter, truer and freer of
twists than conventionally fabricated booms.
A boom member of the character of boom member 30 has been
fabricated from identical extruded U-shaped sections. Each section
was approximately 9.2 inches wide and about 6 inches high. The
central web was about 0.31 inch thick and the flanges were about
0.28 inch thick. As such, the central web was at least about 10
percent thicker than the flanges. When assembled, the hollow boom
member 30 was substantially rectangular and was about 9.2 by 12
inches in transverse cross-section and was about 23 feet in length.
Such boom sections have been formed of aluminum alloys designated
as 5086-H111 and 5083-H111.
The other boom member 32 may be formed of sections 50, 50' which
are made and assembled in a manner similar to boom member 30.
However, because the stresses and loads which boom member 32 must
withstand are less than those which the lower boom member 30 must
withstand, the thickness of central webs 52 and the flanges 54 may
be the same. A first tongue joint member 56 is disposed at one
flange edge and a second complementary groove joint member 58 is
provided at the other flange edge, for juxtaposed interlocking
engagement and securance by a longitudinal weld 60. As such,
identical U-shaped sections 50, 50' may be formed in a single
extrusion die, as were sections 34, 34'.
Boom members fabricated in accordance with this invention are
truer, straighter, freer of twists, and more dimensionally accurate
than conventionally formed booms. They are neat in appearance. The
sections from which they are fabricated are easily and relatively
inexpensively made, and, when made by an extrusion process with a
plurality of integral elongate webs, place the welds remote from
the extreme fibers and provide a greater mass of material at the
extreme fibers and across substantially all without the necessity
of adding separate pieces to strengthen particular webs or
zones.
Although this invention is susceptible of embodiment in different
forms, only a presently preferred embodiment has been illustrated
and described. That embodiment exemplifies the principles of the
invention and is not intended to limit the invention. The scipe of
the invention will be pointed out in the claims.
* * * * *