Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITI.E
TE_ESCOPIC BOO;vl CONSTRlJCTION
_chnical F eld
Thc present invention relates to telescopic booms used for lifting
loads.
Back~,round Art
Telescopi~ booms have been used on cranes, for lifting various
Loads, and have also been used on aerial lift platform apparatus, for supportinga workman's platform at the outer end of the boom. These booms are made
in desired lengths, and some have extended as high as approximately 110 feet,
more or less. ~n the construction of booms of such size, a number of
problems arise. ~Vhen one section of the telescopic boom is caused to extend
outwardly of the larger section which surrounds it, and is then caused to
retract, it is necessary that all of the elements which are intended to pass
acljacerlt to each other are prevented from striking in such a manner as to lockthe boom against further retraction. This problem has been recogniæed to a
certain extent in the prior art. For e,Yample~ Grove U. S. Patent No.
3,243,052 provides a metal skid with a rounded end on the outer end of a
eylinder box, in a rnulti-section telescopic liftinlg boorn. The skid extends
downwaldly from the cylinder box, ancl is intended to permit the bottom pl~t
ot' a section of the boom to rnove past the skid, without locking. Brown et
al U. S. Patent No. 3,620,579 provides a plurality of cylinders with inclined
e~ements or ramps for this same purpose. l'he constructions heretofore
provided, however, have not taken into eonsideration the possibility that other
elements than those at the bottom of the various boom sections may have
meeting suriaees wh;ch could cause a lockup of the boom on retraction, nor
have there been provided other than simple inclined metalic surfaces for this
purpose .
Further, it is known to extend and retract the sections of a tele-
scopic boom by use of both a hydraulic motor and chains or cables. For
example, Grove U. S. Patent No. 3,809,249 discloses a telescopic boom having
three sections, and a cylinder box. A hydraulic motor or cylinder has an end
pin-connected to the base section, and has the outer end of the piston rod
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pivotally connected to a cylinder box, which extends rearwardly from the pin
connection, and is, itself, connected at its rear end to the rear end of the midsection. Sprockets are carried near the rear end of the mid section and at
the front end of the mid section, and a chain extends from the front of the
base section rearwardly around the rear sprocket, and is engaged ~ith the
rear of the fly section, the chain, or a companion chain, e~ctending from the
rear of the fly section forwardly around a sprocket at the forward end of the
mid section, and thence rearwardly to an anchor at the outer end of the base
section. Bv this construction, the cylinder causes the mid section to extend
and retract, and movement of the mid section causes the fly section, also,
to extend and retract, through the chains just described. Where booms are
intended to be of greater length than may be suitably constructed in three
sections, they are made of four, or more, sections, and in view of the
additional seetions, additional problems are encountered. ~or example,
where the cylinder box is pivoted, it is possible that it will engage the chain
or chains for the outer section or sections of the boom, and such engagement
is required to be prevented, to avoid lockup, interference or undue wear on
the parts of the boom. It has been proposed to provide a construction in
which an elongated spacer is provided for supporting a cylinder box, and a
wear pad is positioned between a pair of cables for supporting the mid section
of the boom on the base section. Such prior art disclosures are deficient,
however, in providing a relatively friction-free construction lor longitudinal
movement of the cylinder box relative to a section of the boom, together
with maint~ining the elevation oE the cylinder box so as to prevent
interEerence with the actuating chains.
In connection with the provisions of chains for actuating an outer
section of a boom, such as is shown in Grove U. S. Patent No. 3,809,24~,
there have been provided anchors for the chains which may be tightened, so
as to thereby tighten the chains, as they wear under use and tend to lengthen.
Such anchors have been provided individually for each chain, and are of a
threaded nature. It is difficult in such constructions, however, to tension the
chains equally.
Disclosure of Invention
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The present inventiDn is directed to a multi-section telescopic
lifting boom having fl cylinder box in association with a linear hydraulic
motor for extending and retracting the base section and the next adjacent
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section. One or more additional sections are provided, which are moved by
chains placed in parallel arrangement. At least one telescopic element is
entirely separated from another telescopic element during boom extension, and
is provided with inclined guide surfaces on the top, sides and bottom,
preferably of both cooperating telescopic elements, so as to insure entry of
the smaller element into the surro~lnding element in telescopic manner. These
meeting surfaces are particularly provided on the cylinder box and on the fly
section of the boom. The cylinder box is pivotally connected to the
extensible section adjacent to the base section, at the rear end of the cylinderbox and said section, and thereby the cylinder box is free to pivot about the
pivotal connection; the cylinder box is provided with downwardly extending
wear-resistant blocks, and a bottom plate is provided with longitudinally
extending support surfaces positioned for engagement by said wear-resistant
blocks, the support surfaces preferably being part of longitudinally extending
tubes secured to the bottom plate of the noted section, and the supporting
surfaces of these tubes extending above the level to which chains extending
between these tu~es may rise or occupy, thereby to avoid lockup.
Among the objectives of the present invention are the provision of
a telescopic multi-seetion lifting boom having improved meeting portions for
the prevention of boom lockup or blocking. Another objective is to provide
2~ such a telescopic boom in which the meeting portions are of improved
construction, providing great reliability and being long lasting in use.
Another objective of the present invention is to provide a construction of this
~ypc havin~ an improved arrangement to prlevent interference with the
actu~ltin~ chains. ' et another objective of the present invent~on is the
provision o~ a telescopic boom in which at least one section is extended and
retracted by a pair of chains in parallel, and having improved apparatus for
adjusting the tension on the chains equally.
Brie~ Description of Drawings
Fig. 1 is a schematic, sectional view of a telescopic crane boom in
accordance with the present invention in extended position.
Fig. lA is a view similar to Fig. 1, ~Nith the boom retracted.
Fig. 2 is a cross-sectional view taken on the line 2-2 of Fig. lA.
Fig. 3 is a cross-sectional view showing the outer end of the
cylinder box and the inner end of the fly section in meeting position.
Fig. 4 is a cross-sectional view taken on the line 4-4 of Fig.
3.
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Fig. 5 is a view similar to Fig. 3, and showing the top of the
cylinder box and of the fly boom in meeting position.
Fig. 6 is an enlarged elevational view of the portion of Pig. 1 within
the circle designated 6.
Fig. 7 is a view taken on the line 7-7 of Fig. 6.
Best Mode of Carrying Out the Invention
Referring now to the drawings, wherein like or corresponding
reference numerals are used for like or corresponding parts throughout the
several views, there is shown in Fig. 1 a telescopic crane boom 10 which
includes a base section 11, an inner mid section 12, an outer mid section 13,
and a fly section 14. A linear hydraulic motor 16 has the rear end of the
cylindel thereof connected by a pin 17 to the side walls of the base section
11, at the rear thereof. The piston rod 18 e~ctends forwardly, and is connected
by a pin 19 to the side walls of a cylinder box 21. The cylinder box 21 is
connected adjacent its inner end by a pin 22 to side walls of the inner mid
section 12. To extend and retract the outer mid section 13, the inner mid
section 12 is provided at its rear end with a pair of sprockets 23, and at its
outel end with a pair of sprockets 24. A pair of chains 26, as shown in dashed
~n lines, extend from an anchor 27 on the bottom plate of the base section 11,
thlough an aperture i~l said bottom plate adjacent the outer end thereof, and
thence rearwardly around the sprockets 23, and thence forwardly to an anchor
28 Rt the rear of the outer mid section 13. A second pair of chains or a
secon-~ portion of the chains 26 extend from the anchor 28 around the
sprockets 2~ carried at the outer end of the inner mid section 12, and thence
rearwardly to the anchor 27 at the outer end of the base section 11. To
extend and retract the fly section 14, a similar arrangement is provided,
including sprockets 33 at the rear of the outer mid section 13 and sprockets
3~ at the outer end of the outer mid section 13. A pair of chains 36 extends
around these sprockets, being attached to an anchor 38 adjacent the inner end
of the fly section 14, and to the outer end of the inner mid secton 12.
In Fig lA, the four section telescopic boom 10 is shown in retracted
position, in which a wear block 40 may be seen to engage the bottom plate
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of the fly section 14.
Referring now to Fig. 2, there may be seen the boom in transverse
cross-section, including the base section 11, inner mid section 12, outer mid
section 13 and fly section 14. Each of these boom sections is in the shape
of a hollow rectangle, having top and bottom plates and side plates, as is
known in the art. The cylinder box 21 is a hollow tube of generally square
or rectangular config~ration, and is thereby congruent in cross-sectional shape
with the boom sections. The pin 19 may be seen for connecting the outer end
of the cylinder rod 18 to the cylinder box 21, by being connected to a pair
10of reinforcing plates 21a which are connected to the top and bottom of the
cylinder box 21. A wear pad 21b is carried by the top of the cylinder box
21 for engagement with the underside of the top plate of the fly section 14
in the retracted condition of the boom 10. Other wear pads not shown, are
provided as is known in the art.
Between the bottom plate of the base section 11 and the bottom
plate of the inner mid section 12 there are shown, in cross-sections, a pair
of ehains 26, it being understood that these chains are, in known fashion,
provided in parallel, Qnd each of the chains designated 26 having an upper run
and a lower run. Each of the chains 26 has been herein described as being,
20in faet, two chains, one extending between the anchor 27 (Fig. 1) around the
sproeket 23 and thence to the anchor 28, and the other extending from the
anehor 28, around the sproeket 24 and then to the anehor 27; it will be
nderstood that a single continuous length of chain may be used for each of
th~ two parallel ellains, and also that a similar eonstruetion is provided in
eonneetion with the chain 36, for actuation of the fly section 14.
Also shown in Fig. 2 are the parallel chains 36, with the lower
runs thereof extending between the bottom plate of inner mid section 12 and
the bottom plate of outer mid sectisn 13, with the upper run thereof extending
above the bottom plate of outer mid section 13, and below the bottom plate
30of fly seetion 14.
At the bottom plate of the cylinder box 21 there is a depending
strueture for supporting a pair of laterally spaeed wear resistant blocks 40.
The structure includes a horizontal plate 41, and a pair of vertical plates 42
seeured to the bottom plate of the cylinder box 21. On the bottom plate of
the outer mid seetion 13 are a pair of longitudinally extending tubes 45, each
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h~vln~ ~n uppar surfac~ ~a which i3 in po~lt~on 9ubstanti~11y directly beneath
.he wear resistant blocks 40, for engagement thereby in certain positons of
the boom when extended, referring to Figs. 1 and lA, from the retracted
positon to the extended positon, during which the inner end of the fly section
14 will have passed outwardly of the wear resistant blocks 40, which will then
engage the surfaces 45a, due to the pivoting of the cylinder box 21 about the
pivot pin 2 2 .
Referring now to Fig. 3 there is shown an enlarged cross-sectional
view of the outer end of the cylinder box 21 together with adjacent structure,
the parts being in the position where meeting portions of the cylinder box 21
10and more particularly the wear resistant blocks 40 and the inner end of the
bottom plate of the fly section 14 have just reached engagement. Thus, there
may be seen the plate 41 of the supporting structure depending below the outer
end of the cylinder box 21, supporting the wear resistant block ~0 which is of
a suitable resin material. The outer end of the wear resistant block 40 is
inclined, downwardly from front to rear as shown, and there is provided a wear
plate 46 which defines and provides the meeting portion of the bottom of the
cylinder box 21. The inner end of the bottom plate of fly section 14 is
provided with a similarly inclined guide surface 14A, thereby providing the
meetillg portion of the bottom of the fly boom 14. Accordingly, upon
2~retrnction of the boom 10 the plate 46 will be in position to be engaged by
th~ sl~rface 14A, and will serve to elevate the outer end of the cylinder box
, 50 M9 to c~use it to rise up, the bottom surface of the wear resistant blocks
~I) then cnga~ring the upper surface of the upper plate of fly section 14.
'I'here may also be seen in Fig. 3 a tube 45 mounted on the bottom
plate of the outer mid section 13, as well as the anchor 38 on the fly boom
14, to which the chain 36 is attached. A wear pad 38a is provided beneath
the anchot- 38.
~n Fig. 4, there is shown a side wall of the cylinder box 21, having
adjacent thereto a reinforcing plate 51, there being provided at the forward
30end of the side wall 21 of the cylinder box a block 52 which has an inclined
guide surface 52a which defines the meeting portion of the side wall of the
cylinder bo2c 21. A side wall of the fly boom 14 is shown, having an inclined
surface 14b, providing the meeting portion of the side of fly boom 14. Also
shown is the side wall of the outer mid section 13. As will be understood, the
opposite side walls have a construction substantially identical to that shown in
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Fig. 4, so that should there be an angular deviation of the fly section in a
mQnner to engage either of its side walls with the cylinder block, the
meeting portions thereof will engage, and the guide surfaces will insure the
entry of the cylinder box 21 into the fly section 14.
Referring now to Fig. 5, there may be seen the upper or top
plate of the cylinder box 21, and the substantially parallel top plate of the
fly section 14. A pusher 14c is provided on the top plate of fly section 14,
at the inner end thereof. On the top of the cylinder box 21 there is provided
a guide in the form of an inclined striker plate 53, which extends into the pathof the pusher 14c when the fly section 14 is retracted. The reinforcing plate
51 is an engagement with the inclined portion of the striker 53, to thereby
support both it and the block 52.
Referring now to Fig. 6, there is shown in elevation the outer end
of the base section 11, the bottom plate lla of which has an opening or
aperture llb to permit passage therethrough of the chains 26. Depending from
the bottom plate of the base section 11 is a transverse plate 61 having an
opening 62 therethrough. A yoke 65 is provided, extending laterally, as shown
in Fig. 7, of the base section 11 bottom plate lla. One of the chains 26 has
an end secured to one end of the yoke 65, and the other end of yoke 65 has
the other chairl 26 secured to, it. A transverse pin 66 is carried by the yoke
~S, ~Incl a threaded bolt 67, midway between the chains 26, has one end
JollrllalQd on the pin 6~, the bolt 67 extending through the opening ~2, there
bein~,r a pair Oe nuts 68 and 69 threaded on the bolt 67, the nu-t 68 engaging
a surface of the plate 61. By this construction, when the chains 26 become
elongated through extended usage and consequent wear, adjustment may be
made by using the nut 68 to draw more of the bolt 67 through the opening 62,
and thus move the yoke 65 in a direction to tension both of the chains 26
equally and simultalleously.
There has been provided a multi-section lifting boom having
improved meeting portions at the inner end of the fly section and the outer
end of the cylinder box to prevent boom lockup, or the blocking of entry of
the cylinder box into the fly section. Further, the meeting portions are of
improved construction, having great strength and being capable of long wear
in use. Prevention of engagement of any of the parts of the boom in an
interfering manner with the actuating chains is accomplished through the use
of support surfaces provided at a location above the level of such actuating
chains, and wear resistant blocks supported on a depending structure at
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the outer end of the cylinder bo~, to prevent the cylinder from engaging the
chains. In addition, there has been provided a multi-section telescopic boom
in which at least o~ section is actuated by means of a pair of chains in
parallel, and with improved anchoring of the chains to provide for
simultaneous and equal adjustment thereof.
