US2545937A - Boom - Google Patents

Description

M. ARMSTRONG BOOM 2 Sheets-Sheet 1 Filed Nov. 8, 1947 I U Q Q N N .fizI/ezzfor Mei (If/77 fimszrory d y zYorzzeys March 20,1951 M ARMSTRONG 2,545,937

BOOM

Filed Nov'. 8, 1947 2 Sheets-Sheet 2 Patented Mar. 20, 1951 UNITED STATES PATENT OFFICE BOOM I Merwin Armstrong, Hinsdale, Application November 8, 1947, Serial No. 7 84,813

cables. The cables are normally swung free from the outer free end of the boom and are spaced upright some distance away from this first point of attachment. Across this relatively long span :"the cables normally sag considerably and during operation of the machine the'cables are caused to'whip due to the taking up .of the slack upon application of the load. This whipping of the cable results in the bouncingaround of the heavy boom, subjecting both the boom'and the cable to iexcessive movement resulting in damage requiring frequent replacement of cables.

In the device forming the subject matter of the present invention the boom is designed to support the cable throughout substantially its entire length so as to .eliminatesag in the cable, with the result that there is no bouncing of the boom vwith changing load conditions during operation of the machine. The life of the cables and the boom parts is thereby greatly increased and this 'is accomplished in a relatively simple and yet effective manner, and the weight of the boom structure is reduced substantially below that of the conventional type in present use.

The foregoing constitute some of the principal objects and advantages of the present invention, others of which will become apparent from the following description and the drawings, in

' which Fig. l is a more or less diagrammatic side elevational view of a machine employing a boom embodying the present invention;

Fig. 2 is an enlarged more or less detail view showing the inner connection for the cables and an equalizer therefor;

Fig. 3 is an enlarged, vertical, sectional view through the boom, the view being taken on the line 3---3 of Fig. 1; and

Fig. 4 is an enlarged, fragmentary, vertical sectional view taken through the upper chord of the boom and showing the supports for the cables. I

i For purposes of illustration a single embodiment of the present invention will be described herein, it-being recognized, of course, that many ,modifications may be made without departing from the intended scope of the invention.

5 Claims. (Cl. 212-144) Referringnow to the drawings a heavy machine, such as an excavating machine, is illustrated generally at l and includes a machine base generally indicated at I l. Mounted on this base is a house or machine cab l2.

The boom forming the subject matter of th present invention is illustrated generally at [3 and as shown is provided with a pair of horizontally spaced lower chord members H '(see Figs. 1 and 3), a pair of horizontally spaced upper chord members l and a pair of upwardly extending end truss members, one of which is shown at H5 in Fig. 1. The lower and upper chord members l4 and are connectedtogether at their outermost end indicated at I1 and throughout their lengths there are provided intermediate truss members l8. As bestshown in Fig. 3 aphirality of cross ties l9 are-provided throughout the length'of the lower chords l4.

The boom 13 is pivotally mounted at its lower inner end as at 2! to brackets 22 that are mountedon the machine base ll so that the boom 13 as a unit is adapted to pivot about these pivot connections 2|.

A pair of cables 23 extend throughout the full length of the upper chords [5 and are attached at one end as at 24 to anchor members 25 that are fixed to the outermost end of the boom l3. The other end of each of the cables 23 is fastened to an arm 26, which arm as shown in Fig. 2 is pivotally mounted at one end as at 21 to a bracket 28 on each of the end truss members It. shown in solid lines in'Fig. 2 the cables 23 may be secured as at 29 to the free end of the arms 26.

Referring now to Fig. 1 a framework generally indicated at 30 may be mounted on the machine base H and extend upward y to a position above the house or machine cab l2. A pair of pulleys, one of which is shown at 31 in Fig. 1 may be rotatably mounted at the upper end of the framework 30, and a pair of cables 32 may be adapted to operate over the pulleys 3!. Each of the cables 32 is secured at one end at 29 (Fig. 2) to the free end of the arm 26, while the other end of each cable may pass over a drum or Windlass generally indicated at 33 in Fig. 1. This drumor Windlass is supported on the machine cab l2 and v is powered in any suitablemanner from an enand the other end of the cable passes into the machine cab E2 to a powered Windlass mounted therein. Thus the excavating shovel 35 may be lowered and raised by means of cable 35 passing over the pulley 34. The boom 13 is raised and lowered about its pivot connections 2! by means of cables 32 operating about the powered windlass 33.

Referring now to Figs. 3 and 4 the top chord members l5 are angle members that are adapted to support assubstantially V-shaped plate 3'ithat extends throughout the length of the boom. Spaced throughout the length of this V-shaped plate 31 are a plurality of saddles 38 disposed beneath each of the cables 23 and as best shown in Fig. 4 the cables 23 rest on these spaced saddles 38. Hold-down plates 39 are -dispose'd at spaced intervals on top of thescables-iitiandrthese hold-down plates 39 are clamped downwardly by means of bolt and nut assemblies 40 'so'a-s to loosely engage the cables 23. The cables 23 are adapted to move -:backward forma 1 in a lengthwise direction along theplate 3,! riding on the saddles t8 beneath the hold-.doWn p1ate-3'9, :but vertical whipping of the cables 2'3'is prevented by the fact that the cables are supported throughout their length and are thus prevented from sagging "and also by the fact that-they are held -down'by the hold-down plates 39 and -..are thus ,prevented fromjumping out of the saddles .38.

In the structure just described the straight lower chordmembers M are adapted to take the :direct ithrust load ,to beicarried by the boom 3. "The :cables 23 serve as isuspension :members for the boom and these 10913153 :are-atall timesheld in tension eduring :lowering rand ,raising :oi the beam by the ,relativelyishort cables :3 2 that oper ate about the ,windlass .33. :Each. of the; arms to which :the corresponding short cable 32 is-zattached serves as an-egualizereformaintainin ithe corresponding cable 23:.atal1 times .in tension. 33y movin the lowering and raising cables 32 to the position shown in broken lines 32d and atztaching them at an intermediate point 29a on the arm 26, a proportionate part of the ,loadrnay be carried by the upper chordmembers 15, the Flad-being transmitted bythe arm .26 at its conmection-poi-nt 2'1.

As-shown'in Fig.2 itmayrbe desirable to provide ;a hydraulic-or air cylinder generally indizcatedat '41 which is equipped With-a plunger J12 that is fastened at its free end tothepivotcon- :nection .29 on the upper end of arm 26. The .rinneriend of the plunger '42 is provided withthe usual piston 43 operating in the cy-linder e: and theair or "hydraulic fluid is introduced .llltOaCYlllh- .dc.r=,4-| through suitable pipe connectionefiri-to a ,tank oraccumulator (not shown) having a fixed III-6581128. Thus as the boom 43 is lowered by letting rout or len thening the :cables 32 the egualizer cylinder 4 i tends .toimaintainlthe cables :13 in .taut lcondition with a limited and known load being -carried .by the relatively light members 15,, and the balance of the suspension load beingcarried by the cables 23.

.Ilclaim:

1. A device of the class described comprising a .base member, ;a boom pivotallymounted at one end .to the basecmember and projectin upwardly and outwardly therefrom, .theboom comprising a lower stiff frame member, a continuous top chord connected at .its outer end to the lower member and spaced above the lower member ,at its other end,,and truss members connecting the lower member and the top chord, a cable attached at one end to the outer portion of the boom and extending backward throughout the length of the boom and terminating at its other end adjacent to the inner end of the top chord, the cable being supported throughout its entire length by the top chord, a second cable fixed at one end to the last mentioned terminating end of the first cable and secured at its other end to the base member.

2. A device of the class described comprising a base member, a boom pivotally mounted at one end to Zthe base member and projecting upwardly and outwardly therefrom, the boom comprisin a lower stiff frame member, a continuous top chord connected at its outer end :to the lower member and spaced above the lower .member at its other end, and truss members connectingthe lower member and the top chord,

.arcableattached atone end to the outer portion of the boom and extending backward throughout the length of the boom and terminating at its other end adjacent to the inner end of the 'top chord, :a longitudinally disposed plate sub- .stantially coextensive with the length of the :top :chord and mounted on the top chord, the

cable being supported throughout its 'entire length by said plate, a secondcable fixed .at -one end to the last mentioned terminating end :of

the "first cable and secured vat its other end "to ;member extending from the v:free :end .of the 'boom throughout the .length :of the boom, and

i an upper ;member ssecured:.at. one end :to the :free end of .the lower 1-thrust;.member;and :disposed above the thrust .member, a supportin :calble including along cable secured to :the boom :ad-

jacent the '.'free endtthereof and extending :along the upper member to a iposition at the opposite end of the boom, 'and a :shorter cable secured at one end to the last mentioned :end :of :the

"long cable and at the other end to the :base

member, and supporting means 'on the :upper member engaging the long cable and supporting the long cable substantially throughout. its length.

4. The combination of a basemember, a relatively rigid boom pivoted at 'oneendito 'thebase member 'and having aliree and spaced from the base member, and including a stifi :lower thrust member extending from the free end of the boom throughout the length of the boom, and an upper member secured at one end to the free end of the lower thrust .member and disposed above the thrust member, :a supporting cable including a long cable secured to the booma'djacent the free end thereof and extending along the upper member .to a position 'at .the opposite end of the boom, an equalizer on the 'boomJclisposed adjacent to 'the upper member :and adjacent to the pivot endof the boom, :cabl'e'iastening means on the equalizer, the long cable being attached to the cable fastening means, a shorter cable secured'at one end to thecable fastening means and to the base member at'the other end, and supporting'means on the upper member engaging 'and supporting the long cable substantially throughout its length.

5. The combination of a base member, arelatively rigid boom pivoted at one end to the base member and having a 'free end spaced from the base member, and including a stifi'lower thrust member extending from the free end of the boom throughout the length of the boom, and an upper member secured at one end to the free

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