US3631991A

US3631991A - Underslung winch and sheave structure for telescopic boom assembly

Info

Publication number: US3631991A
Application number: US887227A
Authority: US
Inventors: Raymond J Wacht; Richard J Stallbaumer; Jack E Stilwell
Original assignee: AB Chance Co
Current assignee: PITMAN MANUFACTURING COMPANY Inc (PITMAN) A CORP OF
Priority date: 1969-12-22
Filing date: 1969-12-22
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04

Abstract

Winch and loadline support structure for a utility vehicle provided with a turret thereon mounting a telescopic, extensible boom assembly having a base boom element, and end boom element of insulating material and at least one intermediate boom element. The winch is carried by an intermediate boom element at the outer end thereof in underslung relationship thereto and the support for the winch loadline is mounted on the outer extremity of the end boom element in generally underslung relationship thereto whereby the end boom element may be used in its extended position while the winch remains spaced therefrom toward the turret of the vehicle. As a result, the intermediate winch carrying boom element may be moved in and out without changing the length of the loadline while it is in use. Boom tip members carrying the load line support have outer curved end margins which describe the involute of a circle to facilitate use of the boom tip in handling poles held thereagainst.

Description

Unite States Patent [72] Inventors Raymond J. Wacht Overland Park; Richard J. Stallbaumer, Lenexa; Jack E. Stilwell, Overland Park, all of Kans- [21 Appl. No. 887,227 [22] Filed Dec. 22, 1969 [45] Patented Jan. 4, 1972 [73] Assignee A.B. Chance Company Centralia, Mo.

[54] UNDERSLUNG WINCH AND SHEAVE STRUCTURE FOR TELESCOPIC BOOM ASSEMBLY Primary Examinerl-larvey C. Homsby Attorney-Schmidt, Johnson, Hovey & Williams ABSTRACT: Winch and loadline support structure for a utility vehicle provided with a turret thereon mounting a telescopic, extensible boom assembly having a base boom element, and end boom element of insulating material and at least one intennediate boom element. The winch is carried by an inlcrmediate boom element at the outer end thereof in unilcmlung relationship thereto and the support for the winch loadlinc is mounted on the outer extremity of the end boom element in generally underslung relationship thereto whereby the end boom element may be used in its extended position while the winch remains spaced therefrom toward the turret of the vehicle. As a result, the intermediate winch carrying boom element may be moved in and out without changing the length of the loadline while it is in use. Boom tip members carrying the load line support have outer curved end margins which describe the involute of a circle to facilitate use of the boom tip in handling poles held thereagainst.

PATENTED JAN 4 I872 SHEET 1 OF 2 IN VENTOR5.

UNDERSLUNG WINCH AND SI-IEAVE STRUCTURE FOR TELESCOIIC BOOM ASSEMBLY This invention relates to the field of utility construction vehicles used by utilities, particularly those engaged in the production and distribution of electrical energy, and especially to improved winch structure mounted on the outer end of a telescopic boom assembly rotatably and pivotally mounted on the frame of the vehicle.

High-voltage electrical energy is for the most part transmitted by overhead conductors carried by upright members which are predominantly wooden poles. In the erection of these poles, it is necessary to first dig a relatively deep hole in the ground for receiving the butt end of the pole and to then set the pole in the hole in a truly vertical position. In recent years, utilities have employed multiple purpose power equipment for facilitating not only the digging of holes in the ground of required depth but to also pick up the pole, position it in the hole prepared therefor, and then hold the pole in exact vertical disposition while the ground is tamped around the butt end of the pole. A particularly useful piece of equipment for accomplishing these different jobs haas been available for a number of years and is known generically as a digger derrick. This unit normally comprises a rotatable turret on the frame of a utility vehicle such as a truck and serving to pivotally mount a telescopic boom assembly which generally includes a fixed boom element and one or moore boom element shiftable in and out relative to the fixed boom component. A hydraulically actuated digger suspended from the boom assembly may be selective secured to the movable boom element or elements for movement therewith, or held in fixed disposition alongside the stationary boom element when the digger is not to be used. The movable boom element which is shiftable the farthest away from the fixed boom element generally has a sheave thereon for receiving a loadline so that the boom assembly may also be used as a derrick to pick up poles or other equipment being installed by the linemen. The winch for loadline may be located either at the turret or out on the tip of the movable end boom element depending upon customer preference.

In recent years, utilities have more and more found it desirable to purchase a digger derrick wherein at least the outermost end boom element is of insulating material since it has become a practical necessity to use the equipment in and around energized conductors, as much as anything because of the fact that it is often times impossible or impractical to deenergize the conductors while the workmen carry out operations either directly on the energized lines, or adjacent thereto. The desirability of providing an outer end boom element of insulating material has greatly complicated the problem of providing a winch and sheave assembly on the equipment for use of the machine as a derrick, or to hold poles in position in a hole therefor while earth is tamped around the butt end of the pole. In order to facilitate holding of the poles in proper position for example, many digger derricks are provided with polegripping elements which have arcuate arms movable toward and away from each other so that a pole may be effectively gripped therebetween after it has been raised into position for tamping of earth therearound.

In view of the increased demand for digger derricks having an outer end boom element of insulating material, it is now becoming the practice to provide a telescopic boom assembly having a fixed base boom element pivotally mounted on the rotatable turret and carrying at least a pair of movable boom elements with the one which moves generally farthest from the base boom element being constructed of insulating material such as glass reinforced synthetic resin so that if the end of the boom assembly comes into contact with an energized conductor, the lower boom elements of assembly are still insulated from the high-voltage conductor. Because of the weight limitations inherent in the use of glass reinforced resin boom element though, it is still desirable to provide at least two boom elements of metal, one of which is shiftable longitudinally relative to the stationary boom element so that maximum reach is provided during use of the equipment as a derrick or digger but permitting extension of the fiber glass section if desired for longer reaches where the load thereon is not so great or it is desired to elevate a workman to a level adjacent high-voltage energized conductors.

in view of the critical problems associated with the load limitations inherent in synthetic resin glass fiber reinforced outer boom elements, it can be appreciated that mounting of a boom tip winch on the outer end of the boom element of insulating material further lowers the load limit of the telescopic boom assembly when fully extended and this is of course undesirable in many respects.

It is therefore the primary object of this invention to provide underslung winch and sheave structure for a telescopic boom assembly mounted on a utility vehicle or the like and which is constructed in a unique manner too obviate the problems outlines above without significant sacrifice to the load limit of a digger derrick or similar machine even where the end boom element movable the farthest from the base boom element is constructed of insulating material such as glass fiber reinforced synthetic resin.

It is another important object of the invention to provide improved winch structure for a telescopic boom assembly forming a part of a digger derrick or telescopic crane wherein a winch is mounted on an intermediate movable boom element in underslung relationship thereto, while a loadline receiving support is carried by the outer end of the end boom element movable the farthest from the base boom element so that the end boom element may be extended to increase the reach of the telescopic boom and the intermediate winch carrying boom element may be shifted relative to the base boom element at will without the necessity of paying out or taking in the loadline while it is in use to support a load thereon.

It is a still further important object of the invention to provide underslung winch and sheave structure for a telescopic boom assembly mounted on a utility vehicle or the like wherein the loadline support sheave carried by the boom element movable the farthest from the base boom element is disposed between two boom tip members which have outer arcuate margins which define an imaginary envelope comprising the involute of a circle so as to increase the utility of the boom tip structure in supporting poles held thereagainst regardless of the angularity of the telescopic boom assembly with respect to the pole.

Another important object of the invention is to provide underslung winch and sheave structure for a telescopic boom assembly of the characteristics outlined above wherein the winch which comprises the only structure which requires supply of hydraulic fluid thereto is mounted on the intermediate movable boom element, while the support sheave or roller for the winch loadline which is carried by the outer end of the end boom element requires no power connection thereto, thus simplifying the mechanism and completely eliminating the need for directing hydraulic hoses or other power conductors through or alongside the end boom element of insulating material and which could of course cause significant problems in the construction and operation of the overall machine.

Other important objects of the invention will be explained or become apparent as the following description progresses.

In the drawings:

FIG. 1 is a rear elevational view of a utility vehicle having an extensible, telescopic boom assembly pivotally mounted on a rotatable turret thereon with three boom elements being illustrated, the outennost of which is constructed of fiber glass reinforced synthetic resin material and wherein a winch unit is mounted on the outer end of an intermediate boom element while a boom tip assembly including a loadline support is carried by the extremity of the end boom element and illustrating the way in which the boom assembly is useful in supporting a pole in an upright position while it is held against the boom tip structure by a pole grabber mounted thereon;

FIG. 2 is a fragmentary enlarged side elevational view of the upper part of the boom assembly shown in FIG. 1 and illustrating the pole grabber on the tip structure in another disposition of the same, while an alternate position of the pole grabber is indicated by dotted lines in the figure;

FIG. 3 is an enlarged fragmentary plan view of the boom assembly shown in FIG. 1, but in this case having the end boom assembly of insulating material illustrated in its retracted position, certain parts of the assembly being broken away to reveal details of construction of the components thereunder;

FIG. 4 is a side elevational view of the structure illustrated in FIG. 3 and with parts thereof also being shown in section;

FIG. 5 is an end elevational view of the structure illustrated in FIGS. 3 and 4, with certain parts being broken away to better illustrate the nature of the components there behind; and

FIG. 6 is a fragmentary perspective view of the opposite side of the outer end of the telescopic boom assembly from that shown in FIG. 1 and 2 and with the digger being fragmentarily illustrated in its normal operating position.

In FIG. 1, a conventional utility vehicle 10 which usually comprises a truck is illustrated as supporting digger derrick structure broadly designated 12. For purposes of illustration only, the structure 12 is shown as being mounted on the rear right-hand comer of the frame 14 of vehicle 10, although it is to be appreciated that structure 12 may be carried at various positions on the chassis of the vehicle. In any event, as illustrated, the turret 16 of digger derrick structure 12 is mounted for rotation about a vertical axis and pivotally carries an extensible, telescopic boom assembly broadly designed 18 mounted for pivoting movement about a horizontal axis. The piston and cylinder unit 20 between the base boom element and turret l6 serve to swing boom assembly 18 about the axis of pivot shaft 24.

The base boom element which is illustrated as being of tranversely rectangular configuration and hollow throughout its length, slidably receives an intermediate, transversely rectangular boom element 26 (FIG. 4) which is of metal as is the base boom element 22. A hydraulic piston and cylinder assembly (not shown) is mounted within the base boom element 22 and joined to the intermediate boom element 26 for shifting the intermediate boom element relative to the fixed base boom element. The hydraulic piston and cylinder assembly for effecting this operation is not illustrated since the nature and construction thereof is conventional and well known to those skilled in the art.

An end boom element 28 is fitted within intennediate boom element 26 for reciprocation relative thereto and is shiftable from a fully retracted position as shown in FIG. 3 to an extended location as illustrated in FIG. 1. The end boom element 28 is desirably constructed of fiber glass reinforced synthetic resin material so as to insulate the tip structure broadly designated 30 on the outer extremity of end boom element 28 from the metal boom elements 26 and 22. Hydraulic piston and cylinder structure may be provided for shifting end boom element 28 relative to the other boom elements of boom assembly 18 or the end element 28 may simply be movable manually as desired with a pin or the like being used to secure the end boom to the intermediate boom at any one of a number of selected positions detennined by the number and location of pin-receiving passages through the end boom element.

Referring particularly to FIGS. 3, 4 and 5, it is to be noted that a box-shaped reinforcing member 32 is secured to the outerextremity of insulating boom element 28 and has a pair of upright end flanges 34 on opposite side margins thereof which carry reinforcing bars 36 on the inner opposed faces thereof. When end boom element 28 is fully retracted, the box-shaped reinforcing member 32 is telescoped within an inverted U-shaped metal shroud 38 made up of two L-

shaped sections

38a and 38b partially telescoped over and welded to the outermost end of the metal intermediate boom element 26. The depending side portions of sections 3811 and 38b are each of generally trapezoidal configuration and serve to support an underslung winch unit broadly designated 40.

A tranversely rectangular metal collar 42 telescoped over the outermost end of intermediate boom 26 in proximal relationship to shroud 38 when intermediate boom 26 is retracted, supports hydraulically actuated digger 44 through link 46 connected to collar 42 for swinging movement about an axis extending longitudinally of boom assembly 18, as well as about an axis transverse of the boom assembly when the digger is in depending relationship from the telescopic boom assembly 18. Digger 44 is illustrated in FIG. 1 in its retracted position folded alongside base boom element 22 being FIG. 6 shows the normal operating disposition thereof depending from boom assembly 18 and coupled to shroud 38 by latch 48 on collar 42 which engages the pin 47 on shroud 38. When digger 44 is returned to the stowed position thereof link 46 engages latch 48 to shift the latter out of engagement with pin 47 to uncouple collar 42 from shroud 38. Collar 42 also supports a pair of alignment pins 50 which extend rearwardly from the upper surface of the collar and are adapted to be complementally received within corresponding tubular sleeves 52 therefor mounted on plate 54 carried by the upper surface of base boom element 22.

The structure thus far described is representative of one type of telescopic boom assembly in current use in the construction utility vehicle field and it is to be understood that the novel underslung winch and sheave structure of this invention may be used on telescopic boom assemblies other than that specifically shown in the drawings and described in some detail above.

IN this respect, the underslung winch unit 40, loadline 56 therefor and boom tip structure 30 having an underslung loadline support comprise the improvement of this invention when mounted on a telescopic boom assembly of the general type designated by the numeral 18 as illustrated in the drawings. Winch unit 40 includes a pair of generally

rectangular sideplates

58 and 60 carried by the

side sections

38a and 38b of metal shroud 38, as well'as

tip plate members

62 and 64 of boom tip structure 30. The

plates

58 and 60 are in horizontally spaced, generally parallel, upright relationship and rotatably support a shaft 66 extending transversely of end boom element 28 and carrying a loadline sheave or roller 68 thereon which receives a stretch of the loadline 56 thereover as thus shown in FIG. 5. Bearing structure 70 on plate 60 rotatably supports the end of shaft 66 projecting therethrough, while the opposite end of shaft 66 is coupled directly to gearbox 72 mounted on the outer face of plate 58. Gearbox 72 includes a worm (not shown) which is driven by reversible hydraulic motor 74 bolted to gearbox 72 and extending rearwardly therefrom. Drum 76 on shaft 66 extends transversely of boom assembly 18 and has the loadline 56 trained therearound in serpentine fashion as illustrated in FIG. 5. It is to be noted that drum 76 is located in underslung relationship relative to the boom elements and that the free end of loadline 56 extends forwardly from the upper edge of the drum and is trained over loadline support sheave 68 rotatable between

tip plate members

62 and 64.

The

tip plate members

62 and 64 are both of dogleg configuration so as to permit mounting of sheave 68 in sufiiciently low disposition that the load line 56 passing thereover clears the bottom surfaces of the extensible boom elements of boom assembly 18.

The outwardly directed longitudinally

arcuate end extremities

62a and 64a of

tip plate members

62 and 64 are transversely flared outwardly in opposite directions as indicated in FIGS. 3 and 5 to present inwardly facing convex surfaces for engaging the surface of a pole as for example illustrated in FIG. 1 and designated by the numeral 78. The

end extremities

62a and 64a are longitudinally curved such that an imaginary envelope passing therethrough defines the involute of a circle so as to facilitate grasping of a pole 78 held against tip structure 30 and maintain such pole in engagement with

tip extremities

62a and 64a regardless of the angularity of boom assembly 18 relative to the longitudinal axis of pole 78, and without changing the length of loadline 56 as boom assembly 18 is rotated to vary the angle between the longitudinal axis thereof and the axis of pole 78. Thus, once the pole 78 is snugged against

end extremities

62a and 64a of

tip plates

62 and 64, and the loadline 56 is coupled to the pole, the latter will stay in firm engagement with tip structure 30 as boom assembly 18 is pivoted about the axis of shaft 24 and without the necessity of altering the length of the loadline 56 by operation of winch 40.

Triangular spacer 80 carried by integral sleeves 82 on

bolt units

83 and 85 extending between bars 36, serve to interconnect

plate members

62 and 64 and also mount upstanding, horizontally spaced, parallel ears 84 which cooperate to receive a part of the pole-grabbing mechanism 86 pivotally mounted on

tip members

62 and 64 for rotation relative thereto under the influence of hydraulic piston and cylinder assembly 88. Pole grabber 86 will not be described in detail since it preferably comprises apparatus as disclosed in US. Pat. No. 3,147,993 owned by the assignee hereof and the disclosure of which is incorporated herein by reference.

Although pole grabber 86 can be mounted on tip structure 30 as indicated by the full line showings of FIGS. 1 and 2, the pole-grabbing mechanism may optionally be mounted in the dotted line position of FIG. 2 wherein it is carried by

side plates

58 and 60 of winch unit 40 as well as suitable ears thereof on shroud 38 (illustrated in FIG. 2 only).

In operation, assuming that it is desired to operate the digger derrick 12 as a crane with the end boom element 28 extended as shown in FIG. 1 and locked in position by suitable pin means extending therethrough, or by hydraulic piston and cylinder mechanism located internally of the hollow boom element, it can be seen that the loadline 56 extends forwardly from winch drum 76 and passes over the support sheave 68 before being tied to the object being lifted. In this case, loadline 56 is shown as being joined to a pole 78 held against tip structure 30 and steadied by the arcuate arms of pole grabber 86. During upward lifting movement of boom assembly 18 as illustrated in FIG. 1, the pole 78 is retained in finn engagement with

arcuate surfaces

62a and 64a of

tip plate members

62 and 64 as the angularity between boom as sembly 18 and the pole 78 changes. This is accomplished by virtue of the configuration of

end extremities

62a and 64a defining the involute of a circle wherein such end edges approach the axis of sheave 68 as the lower margins of the tip extremities are approached. As a consequence, it is not necessary to pay in or take out loadline 56 wrapped around drum 76 as the pole 78 is lifted by boom assembly 18 and then lowered into position in the hole prepared therefor by digger 44.

During operation of the hydraulic winch motor 74 in either direction of movement thereof, the load line 56 is taken in or paid out as the case may be while the load suspended from the outer end of the load line is carried from roller 68 remote from winch unit 40. The net result is the provision of a winch having all of the advantages of a boom tip winch is that it is not necessary to take up or pay out the loadline during extension or retraction of intermediate boom element 26, all without significant sacrifice to the load capacity of outer boom element 28 which would occur if the winch unit were mounted on the outer extremity thereof as has heretofore been the practice.

It is thus to be emphasized that the intermediate boom element 28 may be shifted relative to base boom element 22 at will without interfering with the operation of winch unit 40 carried by the outer extremity of intermediate boom element Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a utility vehicle provided with structure thereon mounting a telescopic, extensible boom assembly for rotation and pivoting movement relative to the structure and including a base boom element, an end boom element movable the farthest from said base boom element and at least one intermediate boom element movable relative to the base boom element and said end boom element, the combination with said end boom element and the intermediate boom element relative to the base boom element and said end boom element, the combination with said end boom element and the intermediate boom element of:

a winch unit carried by an intermediate boom element and provided with a drum selectively rotatable in opposite directions about an axis extending transversely of the boom assembly;

a loadline on the drum and having a free end normally extending along the boom assembly in a direction away from the base boom element;

a boom tip assembly on the outer end of the end boom element and provided with a pair of spaced tip members extending outwardly from the end boom element in a direction away from the other boom elements,

each of said tip members being provided with end margins of longitudinally curved configurations adapted to receive a pole thereagainst for support therebywhen the pole is held against the tip assembly by the free end of the loadline wrapped therearound;

a loadline support carried by the boom tip assembly and receiving the free end of the loadline in supporting relationship thereto as the line is payed out or taken in during rotation of the drum in a respective direction,

said winch unit and the loadline support being mounted in underslung relationship to said boom assembly.

2. The combination of claim 1, wherein said winch unit is carried at the outer end of the intermediate boom element.

3. The combination of claim 1, wherein said loadline support comprises a roller mounted for rotation between tip members about an axis extending transversely of the boom assembly.

4. The combination of claim 3, wherein said tip members are of generally planar configuration and extend away from the end boom element in generally parallel relationship to the opposite, longitudinally extending sides of the end boom element, each of said tip members being provided with end margins of longitudinally curved configuration of complemental shape.

5. The combination of claim 4, wherein said end margins lie in an imaginary envelop spaced from the axis of rotation of the roller and describing the involute of a circle having its axis coincident with the axis of rotation of the roller.

6. The combination of claim 5, wherein said end surfaces extend from a level below the upper surface of the end boom element to a level below the lower surface of the end boom element.

7. The combination of claim 1, wherein said winch includes a pair of spaced, parallel plates depending from said intermediate boom element in parallel relationship to the sides thereof, said drum being mounted between the plates for rotation about a horizontal axis extending transversely of the intermediate boom element, and a hydraulic motor and gear assembly operably coupled to said drum .for selectively rotating the same in opposite directions.

8. In a utility vehicle, the combination of: a turret mounted for rotation about an upright axis; a telescopic, extensible boom assembly carried by the turret for pivoting about a horizontal axis relative thereto, said boom assembly including a base boom element, an end boom element of insulating material and movable the farthest from said base boom element, and at least one intermediate boom element movable relative to the base boom element and said end boom element; a winch unit carried by an intermediate boom element at the outermost end thereof and provided with a drum rotatable about a horizontal axis extending transversely of the boom assembly and a motor and gear assembly operably coupled to the drum for selectively rotating the latter in opposite directions, said unit being positioned in underslung relationship to said boom assembly;

a loadline coiled around the drum and having a free end normally extending along the boom assembly in a direction away from the base boom element; and

a boom tip assembly on the outer end of the end boom ele- -ment and provided with a pair of spaced tip members extending outwardly from the end boom element in a direction away from the other boom elements, each of said tip members being provided with end margins of longitudinally curved configurations adapted to receive a pole thereagainst for support thereby when the pole is held against the tip assembly by the free end of the loadline wrapped therearound;

a loadline support roller carried by the boom tip assembly, rotatable about an axis parallel to the axis of rotation of the drum and adaptedto receive the free end of the loadline thereover in supporting relationship thereto as the line is payed out or taken in during rotation of the drum in a respective direction, said support being located in generally underslung relationship with respect to the end boom element.

Claims

1. In a utility vehicle provided with structure thereon mounting a telescopic, extensible boom assembly for rotation and pivoting movement relative to the structure and including a base boom element, an end boom element movable the farthest from said base boom element and at least one intermediate boom element movable relative to the base boom element and said end boom element, the combination with said end boom element and the intermediate boom element movable relative to the base boom element and said end boom element, the combination with said end boom element and the intermediate boom element of: a winch unit carried by an intermediate boom element and provided with a drum selectively rotatable in opposite directions about an axis extending transversely of the boom assembly; a loadline on the drum and having a free end normally extending along the boom assembly in a direction away from the base boom element; a boom tip assembly on the outer end of the end boom element and provided with a pair of spaced tip members extending outwardly from the end boom element in a direction away from the other boom elements, each of said tip members being provided with end margins of longitudinally curved configurations adapted to receive a pole thereagainst for support thereby when the pole is held against the tip assembly by the free end of the loadline wrapped therearound; a loadline support carried by the boom tip assembly and receiving the free end of the loadline in supporting relationship thereto as the line is payed out or taken in during rotation oF the drum in a respective direction, said winch unit and the loadline support being mounted in underslung relationship to said boom assembly.

4. The combination of claim 3, wherein said tip members are of generally planar configuration and extend away from the end boom element in generally parallel relationship to the opposite, longitudinally extending sides of the end boom element, each of said tip members being provided with end margins of longitudinally curved configurations of complemental shape.

5. The combination of claim 4, wherein said end margins lie in an imaginary envelope spaced from the axis of rotation of the roller and describing the involute of a circle having its axis coincident with the axis of rotation of the roller.

7. The combination of claim 1, wherein said winch includes a pair of spaced, parallel plates depending from said intermediate boom element in parallel relationship to the sides thereof, said drum being mounted between the plates for rotation about a horizontal axis extending transversely of the intermediate boom element, and a hydraulic motor and gear assembly operably coupled to said drum for selectively rotating the same in opposite directions.

8. In a utility vehicle, the combination of: a turret mounted for rotation about an upright axis; a telescopic, extensible boom assembly carried by the turret for pivoting about a horizontal axis relative thereto, said boom assembly including a base boom element, an end boom element of insulating material and movable the farthest from said base boom element, and at least one intermediate boom element movable relative to the base boom element and said end boom element; a winch unit carried by an intermediate boom element at the outermost end thereof and provided with a drum rotatable about a horizontal axis extending transversely of the boom assembly and a motor and gear assembly operably coupled to the drum for selectively rotating the latter in opposite directions, said unit being positioned in underslung relationship to said boom assembly; a loadline coiled around the drum and having a free end normally extending along the boom assembly in a direction away from the base boom element; and a boom tip assembly on the outer end of the end boom element and provided with a pair of spaced tip members extending outwardly from the end boom element in a direction away from the other boom elements, each of said tip members being provided with end margins of longitudinally curved configurations adapted to receive a pole thereagainst for support thereby when the pole is held against the tip assembly by the free end of the loadline wrapped therearound; a loadline support roller carried by the boom tip assembly, rotatable about an axis parallel to the axis of rotation of the drum and adapted to receive the free end of the loadline thereover in supporting relationship thereto as the line is payed out or taken in during rotation of the drum in a respective direction, said support being located in generally underslung relationship with respect to the end boom element.