U.S. patent number 3,802,136 [Application Number 05/220,844] was granted by the patent office on 1974-04-09 for extendible crane boom formed of telescopic box-shaped sections.
This patent grant is currently assigned to Leo Gottwald K.G.. Invention is credited to Peter Eiler, Hans Weiskopf.
United States Patent |
3,802,136 |
Eiler , et al. |
April 9, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
EXTENDIBLE CRANE BOOM FORMED OF TELESCOPIC BOX-SHAPED SECTIONS
Abstract
A crane boom is formed of a longitudinally extending base
section and a plurality of extendible boom sections movable between
a retracted position telescoped within the base section and a fully
extended position where the boom sections extend serially outwardly
from the base section. Each extendible boom section has a U-shaped
configuration formed by a pair of longitudinally extending
laterally spaced parallel box-shaped members joined at one end by a
bending resistant transverse member. The box-shaped members have a
trapezoidal cross section sized so that adjacent box-shaped members
nest within one another. Each box-shaped member is constructed by
welding two U-shaped sections together to provide the closed cross
sectional shape. Rollers are arranged within the boom to support
the individual sections as they are extended and retracted. The
extendible boom sections are moved outwardly and inwardly by
hydraulic piston cylinders, with one hydraulic piston cylinder
associated with each of the extendible boom sections. The hydraulic
piston cylinders are located between and extend along the
box-shaped members of the extendible boom sections.
Inventors: |
Eiler; Peter
(Dusseldorf-Benrath, DT), Weiskopf; Hans (Hilden,
Rhineland, DT) |
Assignee: |
Leo Gottwald K.G.
(Dusseldorf-Holthausen, DT)
|
Family
ID: |
22825216 |
Appl.
No.: |
05/220,844 |
Filed: |
January 26, 1972 |
Current U.S.
Class: |
52/115; 52/118;
212/264 |
Current CPC
Class: |
B66C
23/707 (20130101); B66C 23/705 (20130101) |
Current International
Class: |
B66C
23/00 (20060101); B66C 23/70 (20060101); E04h
012/34 () |
Field of
Search: |
;52/115,118,111,123,116
;212/46A,55 ;182/63,141 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,055,159 |
|
Feb 1954 |
|
FR |
|
1,181,101 |
|
Jun 1959 |
|
FR |
|
870,387 |
|
Mar 1953 |
|
DT |
|
1,122,682 |
|
Jan 1962 |
|
DT |
|
Primary Examiner: Purser; Ernest R.
Assistant Examiner: Braun; Leslie A.
Attorney, Agent or Firm: Toren & McGeady
Claims
What is claimed is:
1. A longitudinally extendible crane boom comprising a first boom
section forming the base of said boom and a plurality of second
boom sections telescopically positionable within said first boom
section and extendible from said first boom section in a serially
arranged manner, each of said second boom sections having a first
end and a second end spaced longitudinally from the first end
thereof with said first end located closer to the base of said boom
than said second end thereof, each said second boom having a
U-shaped configuration comprising a pair of longitudinally
extending laterally spaced members and the bight portion of the
U-shaped member comprising a member secured to and extending
transversely of one end of said longitudinally extending members,
said longitudinally extending members fitted in the retracted
position within said longitudinally extending members of said boom
sections located closer to the base of said boom in the extended
position, wherein the improvement comprises that said
longitudinally extending members are box-shaped with each having a
trapezoidally shaped cross-section and in the horizontal position
of the boom and upper and lower sides of the trapezoidally shaped
cross-section are arranged in parallel and said lower side being
narrower in the transverse direction than said upper side, said
transverse member is a bending resistant member, and each said
second boom section comprises a hydraulic piston cylinder extending
in the longitudinal direction of said boom and said hydraulic
piston cylinders of said second boom sections are located in the
longitudinally extending spaces between said box-shaped members of
said second boom sections.
2. A longitudinally extendible crane boom, as set forth in claim 1,
wherein said box-shaped members of said second boom sections are
disposed in parallel relationship to one another.
3. A longitudinally extendible crane boom, as set forth in claim 1,
wherein said transverse member connecting the ends of said
box-shaped members is located at the ends of said box-shaped
members more remote from the base of said boom.
4. A longitudinally extendible crane boom, as set forth in claim 3,
wherein at least one stiffening member is provided on the ends of
said box-shaped members located opposite the ends thereof to which
said transverse members are secured.
5. A longitudinally extendible crane boom, as set forth in claim 3,
wherein said first boom section comprises a single longitudinally
extending box-shaped member and a bending resistant member secured
to and extending transversely of the end of said single box-shaped
member outwardly from the base of said boom, rollers are positioned
on the upper surfaces of the ends of said second boom members
spaced from the end at which said transverse member is located,
said rollers arranged to run on the upper inner surface of the
adjacent said boom section located closer to the base of said boom
in the extended position, guides are provided on the inner upper
surface of said box-shaped member of said first boom section with
said guides disposed at an angle of 45.degree. relative to the
upper surface of said box-shaped members of said second boom
sections, and said guides being arranged to contact said next
outwardly located said second boom section.
6. A longitudinally extendible crane boom, as set forth in claim 1,
wherein said first boom section comprises a pair of longitudinally
extending laterally spaced box-shaped members having the axes
thereof disposed in parallel relationship and a bending resistant
member secured to and extending transversely of the ends of said
box-shaped members at the end of said first boom section spaced
outwardly from the base of the boom.
7. A longitudinally extendible crane boom, as set forth in claim 1,
wherein said first boom section comprises a single longitudinally
extending laterally closed box-shaped member and a bending
resistant member secured to and extending transversely of the end
of said single box-shaped member spaced outwardly from the base of
said boom.
8. A longitudinally extendible crane boom, as set forth in claim 1,
wherein rollers are positioned on the upper surfaces of the ends of
said second boom members spaced from the end at which said
transverse member is located, said rollers arranged to run on the
upper inner surfaces of the adjacent said boom section located
closer to the base of said boom in the extended position, rollers
positioned on each of said transverse members of said second boom
members with said rollers located on the lower side of said
transverse members, and each said second boom section having a
running surface on its underside for running on said rollers of
said transverse members of the adjacent said boom section closer to
the base of said boom.
9. A longitudinally extendible crane boom, as set forth in claim 8,
wherein said lower side of each of said box-shaped members of said
second boom sections forms a running surface which cooperates with
said rollers on said transverse member of the adjacent said boom
section located closer to the base of the boom in the extended
position, the axes of said rollers on said transverse member are
disposed in parallel relationship with the lower sides of said box
members of said second boom sections and the upper sides of each of
said box members of said second boom sections has a pair of
surfaces along the opposite edges thereof arranged at an inclined
position to the upper surface and extending from the upper surface
to the side surfaces of said box-shaped members and the inclined
surfaces arranged at an acute angle to the upper and lower surfaces
of said box-shaped members with each inclined edge surface of said
upper side forming a running surface in contact with said rollers
on the first ends of said second boom sections which said rollers
have their axes extending in parallel relationship with the
inclined edge surfaces of the upper side.
10. A longitudinally extendible crane boom, as set forth in claim
1, wherein each said box-shaped member of said second boom sections
in the horizontal position of the boom comprises an upper U-shaped
longitudinally extending sheet metal section and a lower U-shaped
longitudinally extending sheet metal section with the openings of
said upper and lower U-shaped sections facing toward one another
and the longitudinal edges of the free ends of said upper and lower
U-shaped sections being welded together.
11. A longitudinally extendible crane boom, as set forth in claim
10, wherein said lower U-shaped section having a greater material
thickness than said upper U-shaped section.
12. A longitudinally extendible crane boom, as set forth in claim
1, wherein each said hydraulic piston cylinder comprises a housing
and a piston rod extendible from said housing, the free end of each
said piston rod which projects from said housing is connected to
said transverse member of one of said second boom sections and its
housing is secured at its end from which said piston rod projects
to said transverse member of said second boom section next closer
to the base of said boom in the extended position.
13. A longitudinally extendible crane boom, as set forth in claim
12, wherein each said housing of said hydraulic piston cylinders
has a longitudinally extending guide, and a roller positioned on
the next outwardly disposed housing at the end spaced from the end
from which the piston rod extends so that said roller rides in said
guide as said second boom sections are extended and retracted.
14. A longitudinally extendible crane boom, as set forth in claim
1, wherein the innermost said hydraulic piston cylinder in the
extended position of said boom is secured at the end of its housing
opposite the end from which said piston rod extends to said
transverse member of said second boom section located adjacent said
base boom section in the extended position of said boom and the
free end of said piston rod is secured to said base boom
section.
15. A longitudinally extendible crane boom comprising a first boom
section forming the base of said boom and a plurality of second
boom sections telescopically positionable within said first boom
section and extendible from said first boom section in a serially
arranged manner, each of said second boom sections having a first
end and a second end spaced longitudinally from the first end
thereof with said first end located closer to the base of said boom
than said second end thereof, each said second boom having a
U-shaped configuration with the legs of the U-shaped configuration
comprising a pair of longitudinally extending laterally spaced
members and the bight portion of the U-shaped member comprising a
member secured to and extending transversely of one end of said
longitudinally extending members, said longitudinally extending
members fitted in the retracted position within said longitudinally
extending members of said boom sections located closer to the base
of said boom in the extended position, wherein the improvement
comprises that said longitudinally extending members are box-shaped
with each having a trapezoidally shaped cross-section and in the
horizontal position of the boom the upper and lower sides of the
trapezoidally shaped cross-section are arranged in parallel and
said lower side being narrower in the transverse direction than
said upper side, said transverse member is a bending resistant
member, said first boom section comprises a pair of longitudinally
extending laterally spaced box-shaped members having the axis
thereof disposed in parallel relationship and said bending
resistant member secured to and extending transversely of the ends
of said box-shaped members at the end of said first boom sections
spaced outwardly from the base of the boom, each said second boom
comprises a hydraulic piston cylinder extending in longitudinally
direction of said boom and said hydraulic piston cylinders of said
second boom sections are located in longitudinally extending spaces
between box-shaped members of said second boom sections, a support
guide secured to and extending inwardly from the inwardly facing
side surfaces of said box members of said first boom section, and
rollers secured to the sides of said innermost hydraulic piston
cylinder in the extended position of said boom and fitted into said
support guides on said box members of said first boom section.
Description
SUMMARY OF THE INVENTION
The present invention is directed to a telescopically arranged
longitudinally extendible crane boom and, more particularly, it
concerns the individual extendible boom sections which are formed
of a pair of longitudinally extending laterally spaced box-shaped
members.
Crane booms formed of a welded box-shaped construction have been
successfully employed for providing more favorable static
conditions which afford the absorption of high bending forces.
However, it has been noted that such booms exhibit a so-called
"soft" characteristic in respect to lateral forces when heavy
weights are lifted and, as a result, they tend to yield in the
lateral direction which causes a laterally directed bending moment
to develop. Such a laterally directed bending moment causes a
lateral deflection in the longitudinal axis of the boom especially
when the boom is completely extended and such a bending moment can
be absorbed or eliminated only with considerable difficulty through
the use of brackets.
Accordingly, it is the primary object of the present invention to
provide an extendible crane boom which is suitable for lifting
extremely heavy loads and in which laterally directed bending
moments are absorbed and stabilized.
Therefore, in accordance with the present invention, the boom is
formed of a plurality of individual telescopically arranged
sections with each section formed of a pair of box-like members
joined together at one end by a bending resistant member to afford
suitable restraint against lateral deflection. Further, the
individual box-like members of the boom sections are guided one
within the other to afford adequate support as the boom sections
are extended and retracted. To provide the desired effect, each of
the extendible boom sections is formed of a substantially U-shaped
frame the legs of which are constructed of box-shaped members
connected at one end by a bending resistant transverse member.
Further, each of the extendible boom sections more remote from the
base of the boom are telescopically received within and guided by
the extendible boom section closer to the base of the boom. With
this arrangement a bending resistance is established in the
horizontal direction.
With the present invention a boom construction is provided which
utilizes a relatively small amount of material and provides a
relatively wide laterally extending guide for the individual
sections which is particularly resistant to lateral bending
moments. The transverse members which connect the pair of
box-shaped members in each boom section aid in affording a stable
and bending resistant structure independent of the telescopic
arrangement of the individual boom sections.
For guiding the individual box-shaped members of the telescopically
arranged boom sections within one another, it has proven to be
advantageous if the free ends of the box-shaped members, that is
the ends spaced from the transverse member, are provided on their
upper surfaces with rollers or gliding shoes which, in association
with running or sliding surfaces within the box-shaped members of
the next adjacent boom section in the direction of the base of the
boom, afford a guiding and supporting action as the boom sections
are extended and retracted. Further, the lower surfaces of each of
the box-shaped members are provided with running or sliding
surfaces which ride on rollers or guiding shoes supported in the
transverse member of the boom section closer to the base of the
boom. By this arrangement, the individual box-shaped members can be
supported within one another so that the forces between them are
handled in a simple manner. During use exceedingly high forces
develop in the boom, particularly in the portion of the boom
exposed to compressive forces. For effectively transmitting the
high forces from one boom section to the next located closer to the
base of the boom, the box-shaped members of each extendible boom
section are provided with a trapezoidal cross sectional
configuration. Advantageously, the upper and lower sides of the
trapezoid are formed in parallel relationship to one another and
the lower side or chord is narrower than the upper side or chord.
With this arrangement it is possible to construct the lower side of
the box members, that is the side exposed to compressive forces, in
the manner of a support or guide surface which extends in parallel
relationship with the upper side so that the forces in each case
are introduced into the outer end of each boom section in a
direction which is in parallel with the direction of the action of
the load with the outer end of each boom section acting as a
support or bearing for the next more outwardly arranged
section.
The centering action for the individual box-shaped members of each
boom section is advantageously provided by running or gliding
surfaces on the upper sides of the boom sections which ride along
rollers or gliding shoes arranged on the upper side of the next
adjacent boom section. Preferably, the running or gliding surfaces
are provided at a predetermined angle to the parallel direction of
the upper and lower sides with the rollers arranged in parallel
relationship with the predetermined angle. In constructing the
individual box-shaped members of each boom section, it has been
found to be particularly advantageous if each box-shaped member is
formed of two U-shaped longitudinally extending sheet metal
sections welded together along their free edges and, preferably,
the welding seam is located in the neutral plane between the region
of tensile and compressive forces in the boom section. With such an
arrangement it is possible to adapt the lower portion of each of
the box-shaped members to the load requirements to be experienced
by choosing a thicker section for the lower part of the box-shaped
member so that its entire cross section is not over-dimensioned
with regard to its wall thickness. It should be appreciated that
the lower chord or portion of the box-shaped members is subjected
to greater loads as compared to the remaining surfaces, due to the
bending forces experienced and the arrangement of the guide
rollers. The arrangement of the telescopic boom sections provided
by the present invention affords an exceedingly high stability and
increased support capacity. Moreover, a significant advantage is
achieved by the arrangement of the boom section in that a space is
provided for the means for extending and retracting the individual
boom sections. Accordingly, since the individual box-shaped members
of each boom section are spaced apart laterally, the space between
them affords a central arrangement for the means used in extending
and retracting the boom, such means are preferably hydraulic piston
cylinders. With such hydraulic piston cylinders located in the
space between the box-shaped members they are very easily
accessible and can be serviced in a very simple manner. Further, if
it is necessary to do so, the hydraulic piston cylinders can be
easily replaced without any disassembly of the boom. Due to the
relative movement of and the force transmission through the
individual box-shaped members, which is advantageously achieved
through the bending resistant transverse member which connects the
box-shaped members, many different embodiments are possible and
some of these are illustrated in the embodiments of the invention
shown in the drawing.
In addition to the extendible boom sections described above, the
base boom section, which is connected through at least one luffing
cylinder and a rockable bearing with a bracket or support
arrangement well known in the art, can be constructed in two basic
arrangements in accordance with the present invention. In one
embodiment, the base section can be constructed in accordance with
the arrangement of the telescopic boom sections, that is it can be
formed of two laterally spaced box members disposed in parallel
with one another with a transverse member connecting their ends
remote from the base of the boom in a bending resistant manner.
Alternatively, the base section can be provided as a single
box-like member closed on its upper and lower surface so that in
the retracted position of the boom all of the hydraulic piston
cylinders are enclosed by the single box-shaped member and a
particularly simple protective enclosure is provided for the
hydraulic piston cylinders against the ambient atmosphere and any
other influences which may be experienced.
The various features of novelty which characterize the invention
are pointed out with particularity in the claims annexed to and
forming a part of this disclosure. For a better understanding of
the invention, its operating advantages and specific objects
attained by its use, reference should be had to the accompanying
drawings and descriptive matter in which there are illustrated and
described preferred embodiments of the invention .
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side elevational view of a crane boom embodying the
present invention with the boom shown in a fully telescoped
position;
FIG. 2 is a side elevational view of the boom shown in FIG. 1,
however, with the boom illustrated in its fully extended
position;
FIG. 3 is a front elevational view of the boom shown in FIG. 2;
FIG. 4 is a partial front elevational view, similar to FIG. 3, but
with an alternate arrangement for the base portion of the boom;
FIG. 5 is a sectional view taken along the line V--V in FIGS. 2 and
3;
FIG. 6 is a sectional view taken along the line VI--VI in FIGS. 2
and 3;
FIG. 7 is a sectional view taken along the line VII--VII in FIG.
1;
FIG. 8 is a sectional view taken along the line VIII--VIII in FIG.
4, further, in FIGS. 5 to 8 the position of the hydraulic piston
cylinders is indicated though not shown in FIGS. 1 to 4;
FIG. 9 is a sectional side view of the extended boom showing one
embodiment of the arrangement of the hydraulic piston
cylinders;
FIG. 10 is a view similar to FIG. 9, however, with the boom in its
fully retracted position;
FIG. 11 is a sectional view taken along the line XI--XI in FIG.
10;
FIG. 12 is another sectional view of the extended boom showing an
alternate arrangement of the hydraulic piston cylinders;
FIG. 13 is a view similar to FIG. 12, however, the boom is shown in
the fully retracted position; and
FIG. 14 is a sectional view taken along the line XIV--XIV in FIG.
13.
DETAILED DESCRIPTION OF THE INVENTION
In the drawing an extendible boom is shown which consists of a base
boom section 1 and three extendible and retractable boom sections
2, 3 and 4 which, as shown in FIG. 1, can be telescopically
arranged within the base section 1, and, as shown in FIG. 2, can be
extended in a serial arrangement from the base section 1. As shown
in the drawing, boom section 2 extends immediately outwardly from
base section 1 while boom section 3 extends from boom section 2 and
boom section 4 extends from boom section 3.
At its lower or base portion, the base boom section 1 is connected
in a pivotal manner, by means of a bearing 5, to a bracket or
support plate 6. In turn, the support plate is connected to a
foundation or frame, not shown. A luffing cyinder 7 is connected at
one end to the lower end of the base boom section 1 and at its
other end to the support plate 6 for pivoting the boom about a
horizontal axis. The extendible or telescopic boom section 4,
located most remote from the base boom section in the fully
extended position, note FIG. 2, has a support member 9 at its
outer-most end on which guide rollers or pulleys 8 are mounted.
As illustrated in FIGS. 3 and 4, each of the telescopic boom
sections 2, 3 and 4 is formed of a pair of laterally spaced box
members 2a, 2b, 3a, 3b, 4a and 4b, arranged in parallel
relationship and at their ends more remote from the base of the
boom, each pair of box-shaped members is interconnected by a
bending resistant transverse member 11, 12 and 13 so that each
individual telescopic boom section forms a inverted U-shaped frame.
As indicated in FIG. 1, the box-shaped members of each telescopic
boom section 2, 3 and 4 are telescopically guided within one
another so that in the retracted position the telescopic boom
member 4, located most remote from the base boom section in the
extended position, is the most inwardly located with the telescopic
boom sections 3 and 2 and the base boom section 1 being
concentrically disposed about it, in turn. Further, in the
retracted position, the transverse end members 14, 11, 12 and 13
are in contacting serial arrangement.
In FIGS. 3 and 4, two possible embodiments are shown for the
construction of the base boom section 1.
As shown in FIG. 3, the base boom section 1 can be formed in the
same manner as the telescopic boom sections 2, 3 and 4, that is,
with two laterally spaced box-shaped members 1a, 1b extending in
parallel relation with one another and connected at their ends
spaced from the lower end of the boom by a transverse member 14.
However, an alternative arrangement is shown in FIG. 4, where the
base boom section is constructed as a single box-shaped member 1c,
closed on its top and bottom sides and reinforced in a bending
resistant manner by a transverse member 14 at the outer end of the
box-shaped member from the base of the boom. The arrangement shown
in FIG. 3 affords a very considerable savings in material, while
the arrangement in FIG. 4 has the advantage that in the fully
retracted position all of the movable parts of the extendible boom
are protectively enclosed by the single box-shaped member 1c.
As mentioned above, and as is illustrated in FIGS. 5 to 8, each of
the individual longitudinally extending parts of the telescopic
boom sections 2, 3 and 4 has a box-shaped cross section transverse
to the longitudinal direction of the boom.
To prevent cross sectional deformation in the individual box-shaped
members 2a . . . 4b, inspite of the large loads to which the boom
incorporating the present invention may be subjected, it is
advantageous to provide at least one stiffening member 2c, 3c and
4c at the ends of the box-shaped members closer to the base of the
boom, that is the ends opposite the transverse members 11, 12 and
13. Such end reinforcement increases the load limit of the boom
without increasing the wall thicknesses of the individual
box-shaped sections of the boom. Known telescopic booms which have
used box-shaped members have not been able to incorporate such end
reinforcement because the hydraulic cylinders which effect the
extension and retraction of the sections had to be guided within
the box members. In the present arrangement, as will be clear from
the subsequent description, it is not necessary to locate the
hydraulic piston cylinders within the box-shaped members.
A particularly favorable arrangement of forces and transmission of
forces is achieved with the embodiment shown in the drawing, that
is, with the individual box-shaped members 2a . . . 4b having an
approximately trapezoidal cross section, as shown in FIGS. 5 to 8.
Each of the box-shaped members, including those of the base boom
section 1, where it is formed of a pair of laterally space
box-shaped members 1a, 1b, is constructed of two U-shaped sheet
metal sections, a lower U-shaped section 1d, 2d, 3d, and 4d forming
the lower part of the box-shaped member while the upper part is
formed by an inverted U-shaped section 1e, 2e, 3e, and 4e. The
lower U-shaped sections 1d, 2d, 3d and 4d have outwardly diverging
legs as they extend upwardly from the base of the box member which
is arranged in parallel relationship with the upper or top surface
of the box member. Conversely, the U-shaped sections 1e, 2e, 3e and
4e have inwardly converging sides as they extend downwardly from
the upper part of the box-shaped members. In each box-shaped member
1a . . . 4b the upper and lower U-shaped sections are welded
together along the free edges of the legs of the sections to
provide the closed trapezoidal cross sectional shape. As indicated
in FIG. 7, the lower U-shaped sections 1d-4d have a greater wall
thickness than the upper U-shaped sections 1e-4e, that is, the
lower portions of the boom sections exposed to compressive forces
have a greater wall thickness than the upper portions which are
exposed to tensile forces. The upper sections 1e-4e are provided
with inclined surfaces 21, 22, 23 and 24 which extend
longitudinally along the upper edges of the upper sections
connecting the top surface with the side surfaces. The inclined
surfaces 21, 22, 23 and 24 are nested one within the other and
provide rolling or gliding surfaces which preferably extend at an
angle of 45.degree. to the upper surface of the boom sections, or
the inclined surfaces are provided as supports for rollers or glide
shoes which are arranged at the same angle. As can be seen in FIG.
2, each of the box-shaped members of the telescopic boom sections
2, 3 and 4 is provided at its end closer to the base of the boom
and on the upper side of the box-shaped section with two roller
pairs 32, 33 and 34 which ride along on the inner side of the
inclined surfaces 21, 22 and 23 of the next inwardly located boom
section. According to FIG. 6, and for improving the guiding
characteristics of the boom, each roller of a roller pair may
consist of a double roller which is preferably adjustably mounted
in both planes.
At the location of the transverse members 14, 11 and 12, each of
the boom sections 1, 2 and 3 is provided with a roller pair 35, 36
and 37 which has a construction corresponding to that of the roller
pairs 32, 33 and 34, however, the axis of the rollers is arranged
in parallel relationship with the lower surface of the lower
U-shaped sections of the box-shaped members. The lower U-shaped
sections 2d, 3d and 4d of the telescopic boom sections 2, 3 and 4
ride on the roller pairs 35, 36 and 37, respectively
In the embodiment shown in FIG. 4, in which the base boom section
1, as described above, is a single box-shaped member, the guides or
roller units are constructed in a corresponding manner. As shown in
FIG. 8, the rolelr units 32 of the telescopic boom section 2 are
provided in contact with support surfaces 38 on the box-shaped
member 1c. The support surfaces 38 are disposed at the angle of
inclination of the roller axes, since the box-shaped member 1c does
not contain the configuration of the box-shaped members 1a, 1b as
shown in FIG. 3.
As mentioned above, with the present arrangement an exceedingly
advantageous arrangement of the means for moving the telescopic
boom sections 2, 3 and 4 between the retracted and extended
positions is provided preferably by hydraulic piston cylinders. As
indicated in FIGS. 5 to 8, 11 and 14, the hydraulic piston
cylinders are located in the space between the laterally separated
box-shaped sections of each telescopic boom section. Each of the
extendible telescopic sections 2, 3 and 4 is provided with a
hydraulic cylinder 42, 43 and 44, respectively. In the embodiment
shown in FIGS. 8 to 11, the hydraulic cylinders in the retracted
position are arranged substantially vertically above one another
and the piston rod portion of the hydraulic piston cylinders each
extends in the same direction, that is, toward the top or outer end
of the boom. In this arrangement the cylinder tubes or housings,
which are heavier than the piston rods, are located closer to the
base of the boom so that a more favorable center of gravity
position is obtained. The free ends of the piston rods of each of
the hydraulic piston cylinders 42, 43 and 44, that is, the ends
extending outwardly from the housings, are in each case secured to
the transverse member 11, 12 and 13 of the corresponding boom
sections 2, 3 and 4, and the ends of the housings from which the
piston rods extend are connected to the transverse members 14, 11
and 12, respectively. The free ends of the housings of the
hydraulic cylinders 43 and 44 each has a guide roller 45, 46,
respectively, which ride in guides 47, 48, formed in the housings
of the hydraulic piston cylinders 42 and 43 located in the adjacent
boom section closer to the base of the boom. Further, the end of
the housing of the hydraulic piston cylinder 42 is connected to a
support 49 within the base boom section 1. The manner in which the
hydraulic piston cylinders extend and retract the telescopic boom
sections 2, 3 and 4 can be readily understood from the illustration
provided in FIGS. 9 and 10.
A reinforcement of the guidance for the hydraulic piston cylinders
can be effected in a particularly advantageous manner in accordance
with the embodiment shown in FIGS. 12 to 14. In the embodiment
shown in FIGS. 12 to 14, the hydraulic cylinder 42 located closer
to the base of the boom in the extended position is arranged in a
reversed position as compared to the other hydraulic piston
cylinders 43 and 44, that is, the free end of the piston rod
extends from the housing toward the base of the boom and is
connected to the support 49, while the end of the housing opposite
the end from which the piston rod extends is secured to the
transverse member 11 of the next outwardly arranged telescopic boom
section 2. Since in this embodiment it is not possible to secure
the housing of the hydraulic piston cylinder 42 at the transverse
member 14, in FIG. 14 the inwardly facing side walls of the
box-shaped members 1a and 1b each contains a support guide 51
within which rollers 45 are engaged, the rollers, as shown, extend
outwardly in a suitable manner into the guides. The construction of
the support guides 51 is applicable to a boom where the base boom
section 1 is formed of a pair of box-shaped members. Where the base
boom section 1 is formed as shown in FIG. 4, that is by a single
closed box-shaped member 1c, the support guides are arranged in a
somewhat similar manner supported on the lower wall of the
box-shaped member 1c.
While specific embodiments of the invention have been shown and
described in detail to illustrate the application of the inventive
principles, it will be understood that the invention may be
embodied otherwise without departing from such principles.
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