AU479129B2 - Boom and jib assembly for boom crane - Google Patents

Description

74.67 6174 Abstrcct ~othe Disclosure

This apolication discloses a crane having an

extensible boom consisting of a plurality of boom sections

tdlesconed through Dower means and a jib assembly !ivotally

connected to the outer end of the outer or tip section of

The jib assembly is automatically held in a fixed the boom.

assembly angular position with respect to the boom by a cable

while the boom is extended and retracted. The cable assembly

includes a cable having one end connected to the inner end

of the tip section of the boom and entrained over a pluralit

boom of pulleys rotatable on the remaining sections of the

a mast with the optosite end connected to the free end of

structure pivoted on the outer end of the tip boom section.

connected to the outer end of the jib The mast structure is

assembly t~irough a further cable. The cable assembly will

angle automatically hold the jib assembly at a predetermined relative while the boom sections are extended and retracted

to each other.

Eackaround of the Invention

The present invention relates generally to cranes

a crane of the ty and more particularly to an improvement in

disclosed in U.S. patent No. 3,732,988. In recent years it has become common in the heavy of a duty crane industry to have the crane boom consist retracted plurality of sections that can be extended and length relative to each other to thereby vary the effective for the of the crane which results in greater versatility

entire unit. Furthermore, in many instances, large heavy to duty cranes also incorporate a jib assembly connected

.he other end of the crane. The jib assembly is usually

74.67 6 /74 removable and is only used in instances where extensive

length for the boom is required. The most commnon manner of supporting the jib assem-

bly on the c-ter end of the crane boom is to pivotally

connect the inner end of the jib assembly to the outer end of the outer boom section. The freely pivoted jib assembly is

then held in a fixed position with respect to the outer boom

section by a cable that has one end connected to the outer

end of the jib assembly and the opposite end connected to a

mast structure supported on the outer end of the outer boom

section. Usually, the mast structure is also freely pivoted

on the boom section and is held in a fixed position by a

further cable that extends from the mast structure to another

portion of the crane boom, usually the inner end thereof.

This arrangement substantially restricts the

versatility of the entire unit when the jib assembly is

connected to the outer end of the crane boom. Each time the

effective length of the crane boom is changed, it is necessary

to also change the effective length of the cable or backstay

line that extends from the crane boom to the mast structure. Sur-.arv of the Invention

The present invention incorporates an automatic

adjustment means for the backstay line that supports the jib

assembly on the outer end of an adjustable crane boom so that

the effective length of the backstay line or cable is auto-

matically adjusted to correspond to the effective length of

the crane boom as the crane boom sections are extended and

retracted relative to each other. This results in having

the jib assembly at the same angular position with respect to the boom while the boom sections are being extended and

479,12 9 retracted. 74.6 7 6/74 The cable assenbly consists of a single cable that end has one end connected to the jib assembly and an opposite a connected to the outer end or tip section of the boom and plurality of freely rotatable pulleys on each of the other boom sections with the cable entrained over the pulleys. the The pulleys are arranged so that the effective length of cable assembly between the inner end of the outer boom section and the jib assembly is always equal to the adjusted length of the boom. Brief Description of the Several Views of the Drawings

Fig. 1 shows a fragmentary side view of a self- with propelled crane having the present incorporated therein

many of the conventional crane elements shown in phantom; Fig. 2 is a schematic illustration of the crane

boom and jib assembly; and Fig. 3 is an exploded view of the crane boom and

jib assembly showing the boom in a retracted position. Detailed Description

While this invention is susceptible of embodiment drawings and in many different forms, there is shown in the embodiment of will herein be described in detail a preferred the present dis- ,the invention with the understanding that of the. closure is to be considered as an exemplification to limit the principles of the invention and is not intended

invention to the embodiment illustrated. of In Fig. 1 there is disclosed a crane consisting of which is a vehicle 10 having a boom 12, the inner end a pin 14 on a pivoted about a horizontal axis defined by rotation on a turntable 16. Turntable 16 is supported for 479,129

74,67 6/74 vertical axis on a frame 20 having a plurality of outriggers 22 located at each of the corners to raise the entire frame

a sufficient distance to space wheels 24 about the'ground..

Boor. 12 includes a main or inner boom section

at least one intermediate boom section 32 and an outer end

or tip section 34. The respective boom sections are tele-

scoped with respect to each other for extension and retrac-

tion through suitable power means 36 that has been illustrated

as a pair of fluid rar.-.s 38 each of which has a pair of extensible and retractable elements interposed between

adjacent pairs of boom sections. Power means 36 may take any suitable form but is

preferably of the type disclosed and claimed in U.S. patent

No. 3,657,969, assigned to the assignee of the present

invention. Portions of that disclosure not inconsistent with this disclosure are incorporated herein by reference. As is

disclosed in this patent, the crane boom 12 is adapted to be

pivoted above pivot pin 14 through a suitable fluid ram (not

shown).

Crane 10 also includes a jib assembly 40 that is

freely pivoted by pin 42 on the outer end of tip section 34

and is held in an angular adjusted position with respect to

boom 12 by a cable assembly 44. Cable assembly 44 consists

of a first cable 46 having one end attached to the outer end

of jib assembly 40 and its opposite end connected to one end

of a mast structure 48 that is pivoted at 50 on the outer end of outer boom section or tip section 34. The jib assembly

cable 46 and mast structure 48 may be of the type disclosed

in U.S. patent No. 3,732,988. The remainder of the cable

assembly 44 includes a further cable 52 having one end 47 9,1 2

74.67 6/74 connected to the outer or free end of mast structure 48.

As explained above, heretofore it has been ccmmon

practice to connect the opposite end of cable 52 directly to

the inner end of boc- section 30 adjacent pivot pin 14 so that

jib assembly 40 is held in a fixed position with respect to

boom 12. However, such arrangement precludes the extension

and retraction of boom sections 30, 32 and 34 relative to each

other without changing the length of the cable 52. According

to the present invention, the effective length of cable 52 is

automatically correlated with the effective length of boom

12 as the sections of boom 12 are extended and retracted

relative to each other.

As more clearly shown in Figs. 2 and 3, cable 52 is

of a fixed length with one end connected at 53 to mast 48

and its opposite end connected at 54 to the inner end of the

outer or tip boom section 34. Cable 52 extends forwardly

from the connection 54 and is entrained about a first pulley inter- 56 that is freely rotatable on a bracket 58 carried by

mediate boom section 32. The cable then extends rearwardly

inside hollow intermediate boom section 32 and is again

entrained about a further cable pulley 60 that is freely

rotatable on a bracket 62 fixed to the inner end of inter-

mediate boom section 32. Cable 52 then extends forwardly

and is entrained about a further pulley 64 that is freely

rotatable on a bracket 66 that is carried adjacent the forwarc

end of base or inner end section 30. Cable 52 then extends

rearwardly within inner boom section 30 and is entrained over

a pulley 68 supported on a bracket 70 carried by the boom.

Cable 52 may also extend around a further pulley 72 that is

transversely spaced from pulley 68 and is rotatably supported

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74.67 6 74 by a bracket 74 carried by the ucser end of inner boom

section 30. Bracket 74 is rositioned to have the upper

periphery of pulley 72 located outside the boon section

so that there is an unrestricted portion of cable 52 between

the inner end of inner boom section 30 and rr.ast 48. By proper positioning of pulleys 56, 60, 64, 68,

and 72, all of the cable portions of cable 52 that are located

inside the respective boom sections extends substantially

parallel to each other and the cable portion between pulleys

68 and 72 extends substantially perpendicular to the axis of

boom 12.

VUith the pulley arrangemen.t as described, the effective length of cable 52 between mast 48 and pulley 72

will at all times be equal to the effective length of boom-

12. For example, as the boom sections 30-32 and 34 are

extended relative to each other, the overlapping portions

within each boom section are decreased and this overlapping

portion of the cable is then located outside the boom 12 and

increases the effective length of cable 52 between mast 48

and pulley 72.

As can be appreciated from the above description

the present invention provides a simple and inexpensive

expedient for automatically maintaining jib assembly 40 at

a predetermined angular position with respect to boom 12 as

the effective length of boom 12 is varied. This is accom-

plished by a minimum number of readily available parts that

are substantially maintenance free and can be incorporated

into existing cranes

While two pulleys have been shown at the inner end

of inner boom section, it will be appreciated that pulley 68

479.1 2 9

74. 67 6174 could be eliminatcal aithout changring the operation of the

system.

479,12 9

Claims (2)

7 4.6 7 174 The claims defining the invention are as follows:

1. A crane including an extensible boom having a

plurality of longitudinal hollow boom sections telescoped for

extension and retraction with said boom including at least a

base section and a tip section having a free end, power means

for extending and retracting said boom section relative to

each other, a jib assembly having one end pivotally connected

adjacent said free end of said tip section, a cable assembly

supporting said jib assembly in a predetermined angular posi-

tion with respect to said boom, said cable assembly having

one end connected to said jib assembly at a location spaced

a substantial distance from the pivotal connection, said cable

assembly having an opposite end connected inside said tip

section adjacent the telescoping end, and a plurality of freely

rotatable pulleys on said boom sections with said cable as-

sembly entrained over said pulleys, said pulleys being arranged

to maintain said predetermined angle between said boom and

said jib assembly while said boom sections are being extended

and retracted by said power means.

2. A crane as defined in claim 1, in which said

extensible boom includes an intermediate section between

said base section and said tip section with said plurality.

of pulleys including a pulley adjacent each end of said inter-

mediate section and a pulley adjacent each end of said base

section.

3. A crane as defined in claim 1, in which said

cable assembly includes a mast structure having one end

pivotally connected adjacent said free end of said tip section, a first cable having one end connected to an opposite end of

said mast and a second cable of fixed length having one end 479,129

74.67 6/74 contnccted to said oD-)site end of said mast s;tructure and an

onDroZc end connected to said tip section.

4. 1 crane as 2efincd in claim 3, in which said

-oor'. in?2udcs csrlint-Or..vdiao sczLion b cn said -:se

section and said tip section with a pulley adjacent each end

of said intermcdi ate section and said cable entrained over

said pulleys to produce cable overlapping portions in said

intermediate sections.

DAT-ED this 'I.1INTH day of OCTOBER, 1974

j. i. CASE COMPANY

patent 'Attorneys for the Applicant SPRUSO; FERGUSON

IO

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