US2295509A - Boom and bucket distributing apparatus for concrete mixers - Google Patents

Description

S p 1 C. F; BALL El AL BOOM AND BUCKET DISTRIBUTING APPARATUS FOR CONCRETE MIXERS Filed June 26, 1939 '7 Shee ts-Sheet '1 w W W i E w 8 :0 kg m m a0 a 0 L Sept. 8, 1942. c. F. BALL EIAL 2,295,509-

BOOM AND BUCKET DISTRIBUTING APPARATUS FOR CONCRETE MIXERS Filed. June 26, 1939 i 7 Sheets-Sheet 2 N grwoz/ wbomy CfiarlesfilBall/ and -33 g Louis GJlillcemeien Sept. 8, -1942.

C 'F. BALL EIAL BOOM ANDBUCKET DISTRIBUTING APPARATUS FOR CONCRETE MIXERS Filed June 26., 1939 7 Sheets-Sheet 3 Sept. 8, 1942 c. F. BALL ETAL BOOM AND BUCKET DISTRIBUTING ABPARA'I'US FOR CONCRETE MIXERS 7 Shee ts-Sheet 4 Filed June 26, 1939 II I I HIEI a Y ww awe 1449910 C'fiarlesflfiall and Louis Glfi'lkeme ier;

Sept. 8, 1942 c; BALL EI-AL 2,295,509

BOOM AND BUCKET DISTRIBUTING APPARATUS FOR CONCRETE MIXERS Filed J 1939 I 7 Sheets-Sheet 5 V G h v g i 7 i l l g a j Z B x g Q 32 Q a l v i '1 N i i g Q l Q i m Q g I g l N I I [Il i g Q I I Q s R gwumvbo'm' I: Lharleal'ZBallw Louis GCHilkemeier; i

Sept. 3, 1942- c. F. BALL ETAL 2, 95,509

BOOM AND BUCKET DISTRIBUTING APPARATUS FOR CONCRETE MIXERS 7 Sheets-Sheet 6 F iled June 26, 1939 gwumtom v C'ILQJ'ZESJ'ZBQZZ an Louis GHilkemeier;

Sept. 8, 1942. c. F. BALL EI'AL 2,295,509

BOOM AND BUCKET DISTRIBUTING APPARATUS FOR CONCRETE MIXERS 7 Shee ts-Sheet 7 Filed June 26, 1939 Patented se t. 8,1942

BOOM AND BUCKET DISTRIBUTING AP- PARATUS FOB CQNCRETE MIXERS.

Charles F. Ball, Wauwatosa, and Louis G. Hilkemeier, Milwaukee, Wis, assignors to Chain Belt Company, Milwaukee, Wis., a corporation of Wisconsin Application June 26, 1939, Serial No. 281,299

8 Claims. 101. 104-92) The invention relates to boom and bucket distributing apparatus for concrete mixers, and has for its principal object to provide improved mechanism for accomplishing reciprocatory traverse of the bucket along the boom, and for raising and lowering the latter.

It is now almost universal practice to equip concrete mixers of the paving type with mechanism for distributing the mixed concrete discharged from the mixing drum over areas of con- 10 siderable extent. Such mechanism commonly comprises a horizontally disposed boom of from' twenty .to thirty five feet or more in length, having one end suitably pivotally mounted adjacent driven oppositely running sprockets or gears, each having a clutch, preferably of the friction type, associated with it, and means under manual control of the operator for actuating the clutches whereby the sprockets or gears maybe optionally clutched one at a time to a driven shaft. The said shaft is arranged to drivea winding drum "for the bucket cables through another clutch,

which may be of the double jaw type, adapted in one position to transmit power to said drum and in another position .to transmit power, preferably through an irreversible worm drive, to a spool the discharge opening of the mixing drum for both horizontal and vertical swinging movements, and a receptacle or bucket mounted on such boom for reciprocating travel from and to said discharge opening. The outer end ofthe boom is supported by a block and tackle extending from 2 the boom to the main frame of the mixer, by means of which the boom may be raised and lowered in a vertical plane about its horizontal pivot. The bucket, which may hold a complete upon which the boom raising and lowering cable is wound. The bucket operating cables are so wound upon their drum that upon rotation of the latter in a given direction, one cable will be unwound while the other will be simultaneously wound thereon, taking the place of the cable which is leaving; and the said cables pass over suitable pulleys or sheaves mounted upon the frame of the mixerand upon the boom, whereby they are guided to the bucket, to which they are each attached. The drum also has means assobatch of a cubic yard or more of mixed concrete,

is usually reciprocated onthe boom at the will of the operator by means of cables which are power driven in various ways from .the engine or motor which drives the mixing drum, and one of the prime objects of the present invention is to provide improved means for actuating these cables.

, The swinging movements of the boom in the horizontal plane occur quite frequently in the normal operation of placing concrete pavement,

and are usually accomplished through the use of manually controlled power drives, such for example, as that disclosed and claimed in our copending application filed June 26, 1939, Serial No 281,298 entitled Boom swing mechanism for concrete mixers. On the other hand, pivotal movement of the boom upwardly or downwardly in a vertical plane is necessary only at infrequent intervals, and while such movement may be accomplished by manually operable means, still because of the weight of the parts it is preferable to also actuate the boom elevating and loweringdevices by power. The present invention therefore contemplates the provision of means whereby the raising and lowering mechanism may be actuated by power at the volition of the operator through a simple connection to the drive mechanism for the bucket cables. f

Briefly, the cable drive mechanism of the presciated with it whereby rotation of the drum will cause axial travel of the same, thereby always maintaining the entering and leaving points of the cables upon the drum in substantial alinement with the adjacent sheaves about which they pass.

Knockouts are also provided arranged to automatically disengage the main driving clutches as the bucket reaches either end of the boom, and a brake is also associated with the clutch shaft, having control means whereby it is automatically released whenever either main clutch is engaged and automatically applied whenever both clutches are disengaged. Thus thebucket will be quickly stopped as either main clutch is disengaged, and

will be positively held by the driving cables in whatever position itmay occupy whenever both clutches are disengaged.

Since it requires more power to move the loaded bucket outwardly from the mixer than-it does to return it after being emptied, the out-drive clutch is preferably of heavier construction than the indrive clutch, and may conveniently tak the form of a multiple disk clutch, whereas the iii-drive clutch may be of the single or double plate type.

With .the above and other features in view which will appear as the description proceeds, the invention comprises the novel details of construc- .tion and combinations and arrangements of parts ent invention comprises a pair of constantly 5 more fully hereafter disclosed and particularly pointed out in the appended claims Referring to the accompanying drawings forming a part of this specification, in which like reference characters designate like parts in all the.

views:

Figure 1 is a diagrammatic side elevational view, partly broken away, of the discharge end of a paving concrete mixer equipped with a-boom and bucket distributing apparatus, and showing one form of bucket operating and boom elevating mechanism constructed in accordance with the present invention applied thereto Fig. 2 is an enlarged elevational view of the vmechanism constituting the invention, as seen boom 26 about its pivot 30 are accomplished by I taken approximately on the plane indicated by v the line 4-4 of Fig. 2, looking in the direction of the arrows, showing the brake in applied position;

Fig. 5 is an enlarged detail sectional view of a portion of the brake control mechanism, taken on the plane indicated by the line 55 of Fig. 4, looking down;

Fig. 6 is a view similar to Fig. 3 and on the same scale, of the central portion of the apparatus shown in Fig. 2, illustrating the bucket cable winding drum, the means for producing axial movement thereof, and a portion of the main clutch knockout mechanism;

Fig. 7 is a transverse sectional elevational view, taken on the plane indicated by the line 1-1 of Fig. 6, looking in the direction of the arrows;

Fig. 8 is a view similar to Fig. 7, taken on the plane indicated by the line 8 -8 of Fi 6; and

Fig. 9 is a horizontal sectional view of the left hand portion of the apparatus illustrated in Fig.

2, taken approximately on the plane indicated by theline 39 in said figure, showing the spool for the boom raising and lowering cable, the drive mechanism therefor, and the double clutch for selectively connecting the drive to either the bucket cable winding drum or the boom cable spool.

Referring more particularly to Fig. 1 of the drawings, there is shown the discharge end of a typical paving mixer which may comprise a frame having the horizontal members l5, l5, vertical members l1 and a transverse member Ill. The said frame is mounted upon crawler treads l3 and has the mixing drum 20 mounted within it upon suitable supporting rollers 2|. The said drum is provided with the usual axial discharge opening 22, see Fig. 2, which may be surrounded by a drip ring 23, through which the mixed concrete is discharged by means of suitable discharge chute members 24 into a distributin bucket 25. This bucket is mounted for reciprocating movements upon a boom 26 by means of a carriage or trolley 21 and is adapted to bemoved inwardly and outwardly along the boom by the out-drive cable 28 and the in-drive cable 23, all as may be readily understood by those [skilled in the art. The said cables are trained about sheaves l8 fixedly mounted on the frame member i8, and 26 mounted on the boom 25, the peripheries of which sheaves are substantially tangent to the plane of the axis of the vertical pivot 3| of the boom.

The end of the boom adjacent the mixer is pivotally mounted as at 33 for vertical swinging movements of the boom and as at 3| .for horizontal swinging movements of the same, which horipending application Serial No. 281,298 referred to above.

The raising and lowering movements of the a block and tackle mechanism which includes the elevating and lowering cable 34 and the bucket traverse inwardly and outwardly on the boom is accomplished through the mechanism constituting the present invention which is generally indicated at 35. As fully set forth in our said copending application, power for accomplishing the horizontal swinging movements of the .boom through the mechanism 33 is derived from the main power plant of the mixer through a drive from the mixing drum 23 which comprises a ring gear or sprocket 35, chain 31 engaging therewith and a sprocket 33 carried by the drive shaft 33 of the boom swinging mechanism 33. As is also fully disclosed in our said co-pending application, the boom swingingmechanism 33 includes a pair of oppositely driven sprockets 40 and 4| which serve as driving means for the bucket operating mechanism and boom raising and low-,

comprises a shaft 45 which is journalled by a ball or other anti-friction bearing '45 in a bearing bracket 41 rigidly mounted upon the frame members it and 18. The said shaft has journalled upon it spaced sprocket wheels 43 and 49 about which are trained the chains 53 and 5| respectively, which also engage the sprockets 40 and 4| respectively, of the boom swinging mechanism 33, whereby the said sprockets 43 and 49 are.constantly driven in opposite directions. power transmission and has associated with it clutch annuli or members 52 (see Fig. 3) carrying suitable clutch facings 53 and operatively connected to the sprocket by means of pins or studs 54 to compel rotation as a unit and yet permit axial movement of members 52 for accomplishing their clutching function and to allow for wear of facings 53. rigidly secured to the shaft 45 adjacent the sprocket 48 and together with the pressure ring. 55, constitutes the driven element of the indrive' clutch inasmuch as the clutch annuli 52 carried by the sprocket 43 are arranged to be optionally clamped between the flat faces of the ring '53 and of the drum 55 as will be readily understood. The engaging and disengaging movements of the clutch annuli are accomplished through the said pressure ring 55 which is mounted upon a clutch hub- 31 rigidly secured to shaft 45. The ring 58 is axially movable on the said hub by means of the clutch fingers 58 operable through links 53 by the shifting col- 0 lar 50 which in turn is axially movable by the The sprocket 43 constitutes the in-drive A brake drum 55 is 2,295,509 in co-operative relation with the driven clutch disks 51 which are carried by the hub 88 keyed or otherwise rigidly secured upon the shaft 45. Frictional en agement between thedisks 88 and 81 is accomplished through a pressure ring 88 slidably mounted upon an extension of the hub 88 and movable by the clutch fingers 18 which are operable through links "from the clutch collar 12 which in turn is reciprocated by means of the operating lever I3 which engages with the pins 14 carried by the clutch operating yoke 15. Release springs I16 of any ordinary or usual construction may be included .to secure disengagement of the clutch elements 85 and 51 as will be readily understood.

Since the bucket 25 when filled with a batch of mixed concrete amounting to a cubic yard or more requires considerably more power in its outward movements along the boom than itdoes during its inward movement after the concrete has been discharged, the out-drive clutch just described is preferably of heavier construction than the in-drive clutch comprising the annuli 52, brake drum 55, and the pressure ring 58.

Asbest shown in Figs. 3 and 4 a pair of brake shoes 16 are pivotally hung as at I" in the bearing bracket 41 and surround the outer cir-' of the sprockets 48 and 48. The eye-bolts 88 at either end of the rod 84 permit adjustment of the parts to secure proper initial relationship of the brake .and clutches, and also permit of compensation for alterations in the relationship of the shifting levers 8| and I3 as the clutches are taken up for wear.

The rod 84 is provided with a stud 81 which is engaged by one armof a lever 88 (see Fig. 2), another arm of which is provided with an operating handle 88 by means of which the operator 1 mayshift the rod 84 and clutch operating levers are normally urged into engagement with the said drum 55 by springs 11 mounted upon the rod 18 and the pressure of which may be suitably adjusted bysthe adjusting nuts 18. The

shoes are normally in frictional contact with the brake drum whenever the two clutches are disengaged so that the shaft 45 will be posi tively held against rotation at such time; However, as either clutch is moved to engaging -position by its lever 6| or I3, and the parts associated therewith, the brake will be releasedlby the following mechanism:

Pivotally mounted upon the extension 88 of the housing of the boom swing mechanism 83 the-latter, the other cable will be wound thereon 40 is a pair of levers 8| the upper ends ofwhichare crossed as clearly indicated in Fig. 4, and

are engaged by adjustable stop screws 82 carried by the lower ends of the brake shoes I8. By

adjustment of the said screws 82, wear of the brake lining may be compensated, aswill be readily understood. The lower ends of the levers 8| have rollers 83 journalled upon them which rollers are alined with a rod 84, the ends of which are adjustably connected by eye-bolts 88 85, as will be readily understood. However, whenever the clutch operating levers 8| and'lt are moved to engage one or the other of the main driving clutches the rod 84 will be likewise moved to bring the recesses 85 out of alinement with the rollers 83 subjecting the latter to the full diameter of the rod 84 and causing a rocking of the levers 8| about their pivots whereby their upper ends will cause a spreading of the brake shoes against the action of springs 11 and disengagement of the brake lining from the periphery of the drum 5. Thus as either clutch is engaged the brake will be released and the shaft which is leaving:

8| and 13 to produce engagement of either the in-drive or out-drive sprocket with the shaft as desired.

The shaft is provided at its left hand end,

.This shaft is journalled in bearings 83 carried by a tubular shaft 84 which surrounds the shaft 82 and is Joumalled in suitable anti-friction bearings 85 carried by hearing brackets 88 and 81 supported by the frame members I8 and I8. A winding drum 88 is freely mounted upon the tubular shaft 84 for longitudinal sliding movements thereon and the inner periphery of the drum is provided with a pair of longitudinal keyways 88 which slidably receive keys I88 carried at the outer ends of the arms of a driving member I8l which is keyed, or otherwise rigidly secured to the tubular shaft 84. The outer periphery of the drum-.88 is provided with a helical groove.

I82 for'the reception of the out-drive cable 28 and the in-drive cable 28 which cables are wound upon the said drum in opposite directions as is common in the art, wh'ereby as one cable is unwound from the drum through the rotation of taking the place of that portion of the cable Inasmuch as the sheaves or 'pulleyson the mixer frame over which the cables pass after 'they leave the drum are fixed, andsince the entering-and leaving points of the cables upon the drum is constantly shifting longitudinally of the latter as the cables-are woundland unwound, provision is made according to the present invention to shift the drum axially as it is'rotated so as to maintain the entering and leaving points ofthe cables upon the drum in substantially constant planes whereby the cables may be fed to and taken fromthe frame carried *sheaves in substantial alinement therewith, and cable strain and wear prevented. As here shown, the means for producing axial movement of the drum 88 comprise a screw I83 rigidly connected-to one 45 will befree tobe driven by one or. the other 76 end of the drum and engaged by a relatively flxed nut I84. This nut carries an upstanding arm I which non-rigidly engages a bracket member I88 mounted upon the frame member'l8 whereby rotation of the said nut is prevented. The said nut is also connected by means of a pair of links I81 (see Figs. 2, 'Z and 9) with the fixed bearing bracket 88 which links prevent axial movement of the nut I84 while ne'vertheless permitting of limited transverse movement of the latter as does also the non-rigid-connection between the arm I85 and the bracket I88. The nut is thus arranged to accommodate itself to alinement with the shaft 84 while at the same time rotation and axial movement of the nut are prevented.

A rod I88 is slidably'mounted at one end (see Fig, 2) in a depending extension I88 of the bearing bracket 88*and the other end of the said rod shiftable clutch member I20 The left hand face of the member I20 will be out clutch member I I8.

is pivotally connected as at III to the clutch operating lever 6|. The 'rod I09 rigidly carries a pair of adjustable knockout arms I I I which extend upwardly and embrace the tubular shaft 9|, the said arms being so located upon the rod I09 as to be engaged by the hub of the right end plate of the drum 98 or by the end of the screw I03 respectively as the drum 99 approaches the limit of its axial movement in either direction. Upon such contact the drum will move the engaged arm III together with the rod I in whichever direction the drum happens to be traveling, and

in a bracket and housing I I4 secured to a frame member I8. Said shaft I I3 carries a worm wheel IIS which is engaged by an irreversible worm I I6 carried by a shaft I II which is in axial alinement with the shafts 92 and 94. The tubular shaft 92 has keyed to its left hand end, as viewed in Figs. 2 and 9, a clutch member II8 which is arranged for engagement with companion clutch elements formed on the right hand face of a which is splined upon the shaft 92. said member I20 is also provided with clutch elements arranged for engagement with companion elements carried by a clutch member I I9, which may be journaled upon the end of shaft 92, and which may also constitute one element of a flexible coupling, the other element I25 of which is keyed on the shaft H1. The shiftable clutch member I20 is arranged to be moved axially upon the shaft 92 by a shifting yoke I2I, which in turn is actuated by a lever I22 and a link connection I23 from a hand lever I24 located at the opposite side of the machine adjacent the operators station. As here shown these clutches may be of the jaw type and when in the position shown in Fig. 9 the shaft 92 will not be transmitting power to either the shaft 94 or to the shaft I", but the normal position is of course such that the driving clutch member I20 is in engagement with the driven clutch member H8 on the shaft 94 so'that the latter shaft may drive the winding drum 98 as above described. However, when it becomes necessary or desirable to elevate or lower the boom 26 the clutch member I20 will be shifted through its mechanism I2I,

- I22, I23 and I24 to disengage the driven clutch member H8 and to engage the member II9, whereupon the shaft 92 will transmit power to the shaft-I ll, worm IIS, worm wheel H5, spool shaft H9 and spool II2, whereby the boom elevating and lowering cable 34 will be wound upon or unwound from the spool .I I2 to raise or lower the boom 26, as will be readily understood.

As above indicated, the boom is only raised or lowered infrequently and normally the clutch of engagement with the clutch member IIS and in engagement with the While one form of trated and described it is obvious that those skilled in the art may vary the details of construction as well as the precise arrangement of parts without departing from the spirit .of the the invention has been illusinvention and therefore it is not wished to be limited to the above disclosure except as may be required by the claims.

What is claimed is:

1. In a concrete mixer having a frame, a mixing drum mounted therein, a boom pivoted on said frame for horizontal swinging movements. sheaves carried respectively by said frame and boom adjacent said boom pivot, a distributing bucket mounted on said boom for traverse thereon, cables connected to said bucket and passing around said sheaves, cable-operating mechanism comprising a winding drum for said cables, mounted on said frame for rotary and axial movements, the latter in a plane substantially parallel to the axis of said frame-carried sheaves; means for rotating said winding drum in either direction at will; a screw carried by said wind ing drum; a nut engaging said screw; and means floatingly connecting said nut to said frame against rotation and axial movement while providing for movement thereof transversely of the axis of the screw; said screw and nut causing axial traverse of the winding drum as it is rotated to maintain the entering and leaving points of the cables on such drum in alinement with the frame-carried sheaves.

, 2. In a concrete mixer having a frame, a mixing drum .mounted therein, a boom vertically cables mounted on said frame intermediate said sheaves and the end of said mixing drum, with its axis horizontal and transverse to that of the latter, and substantially parallel to that of said sheaves; means for rotating said winding drum in either direction at will; a screw carried by said winding drum; a nut engaging said screw; pivoted links connecting said nut with the frame, for preventing axial movement of the nut while providing for movement thereof transversely of the screw axis whereby the nut may aline itself with the screw; and an arm carried by the nut and engaging the frame, providing for said transverse movement of the nut while preventing rotation thereof.

3. In a concrete mixer having a frame, a mixing drum mounted therein, a boom pivotally mounted on said frame for horizontal swinging movements, sheaves carried by said frame adjacent the boom pivot, a distributing bucket mounted for traverse on the boom to and from the discharge end of said drum, cables passing around said sheaves and connected to said bucket for causing said traverse thereof, operating mechanism for said cables comprising a shaft journaled transversely of said frame adjacent said boom pivot; constantly-operating, oppositely.- running driving members journaled on said shaft; a normally applied brake carried by the shaft preventing rotation thereof; a cable winding drum carried by said shaft for rotational and axial movements; means for causing said axial movements of the winding drum as it is rotated,

whereby to maintain the entering and leaving with said sheaves; manually operable control means for alternatively connecting said driving members to said shaft and releasing said brake mixing receptacle provided with a discharge opening, a boom extending from adjacent said opening, a material-receiving bucket mounted on said boom for traverse to and from said opening, and

actuating cables for said bucket, means for causing traverse of said bucketalong said boom in either direction at will, comprising a rotatable,

axially fixed shaft; means for alternatively driving said shaft in either direction; a winding drum about which said cables are trained, splined to said shaft for rotation therewith and axial movement relative thereto; a screw-threaded member carried by said drum; and a relatively v fixed nut engaged by said threaded member,

whereby rotation of the drum in either direction by said shaftwill cause axial movement of the drum relative to the shaft and maintain the entering and leaving points of the cables in substantially constant planes as they are wound upon and unwound from the drum.

5. In a concrete mixer of the type having a mixing receptacle provided with a discharge opening, a boom extending from adjacent said opening, a material-receiving bucket, mounted on said boom for traverse to and from said opening, and actuating cables for said bucket, means for causing traverse of' the bucket along the boom in either direction at will, comprising a tubular shaft; a winding drum about which said cables are trained, splined to said tubular shaft for rotation therewith and axial movement relative thereto; a screw-threaded member rigid with said drum; a relatively fixed nut engaged by said threaded member, whereby rotation of said drum in either direction by the shaft will cause axial movement of the drum thereon and maintain the entering and leaving points of the cables on the drum in substantially constant planes as they are wound upon and unwound from the drum; a second shaft mounted within said tubular shaft;

movement; and a threaded sleeve carried byv said means for alternatively driving said second shaft in either direction at will; and means for making and breaking a driving connection between the two shafts at will.

6. In a concrete mixer of the type having a mixing receptacle provided with a discharge opening, a boom extending from adjacent said opening, a material-receiving bucket mounted on said boom for traverse to and from said opening, and actuating cables for said bucket, means for causing traverse of the bucket alongsaid boom in either direction at will, comprising a shaft; means for alternatively driving said shaft in either direction; a winding drum about which said cables are trained. splined to said shaft for rotation therewith and axial movement thereon; a nut surrounding said shaft, said nut being mounted for movements transversely of the shaft axis but being held against rotation and longitudinal drum, surrounding said shaft and engaging said nut, whereby. rotation of the drum in either direction bythe shaft will cause axial movement of the drum and maintain the entering and leaving points of the respective cables on the drum in substantially constant planes as they are wound thereon and unwound therefrom.

'7; In a concrete mixer of the type having a frame, a mixing receptacle provided with a discharge opening, a boom extending from adjacent said opening, a material-receiving bucket mounted upon the boom for traverse to and from the opening, and actuating cables for said bucket, means for causing traverse of the bucket along the boom in either direction at will, comprising 1 a shaft; means for alternatively driving said shaft in either direction; a winding drum about which said cables are trained in opposite directions. splined to said shaft for rotation therewith and axial movement thereon; a nut surrounding said shaft; connections between said nut and the frame for preventing rotation and longitudinal movement of the nut while providing for its movement transversely of the shaft axis, whereby it may accommodate itself to the alinement of the shaft, said, connections including a link piv otally connected to the frame and. to the nut for preventing its longitudinal movement, and a member carried by the nut engaging the frame to prevent its rotation while providing for its movement transversely of the shaft axis; and a threaded sleeve carried by the drum, surrounding said shaft and engaging the nut, whereby rotation of the drum in either direction by theshaft will cause axial movement of the drum andmaintain the entering and leaving points of the respective cables upon the drum in substantially constant planes as hey are wound thereon andunwound therefrom.

8. In a concrete mixer of the type having a frame, a mixing receptacle provided with a discharge opening, a boom extending from adjacent said opening, a material-receiving bucket mounted upon the boom for traverse to and from the opening, andactuating cables for said bucket;

,means for causing traverse of the bucket along x the boom in either direction at wfll, comprisinga tubular shaft; a winding drum about which said cables are trained in opposite directions, splined to said shaft for rotation therewith and axial movement thereon; a threaded sleeve rigid with said drum and surrounding said shaft; a nut engaging said sleeve; connections between said nut and the frame for preventing its rotation and longitudinal movement while its movement transversely of the aft axis; a second shaft mounted co-axially within said tubular shaft; means including a pal of constantly operating oppositely running clutc members,'and

companion clutch members alternatively engageable therewith, for alternatively driving said sec-' end shaft in either direction at will; and clutch means for making and breaking a driving connection between said shafts,

roviding. for

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