Carrier Track Assembly for Extensible and Retractable Boom Machines

Various track assemblies have been proposed for extensible and retractable boom machines such as cranes, aerial work platforms and the like, for supporting flexible hoses and cables required for transmitting power to the work unit mounted on the outermost end of the telescopic boom. Conventional track assemblies include a flexible carrier constructed and arranged to bend at least 180.degree. about its transverse axis but prevented in bending about the transverse axis in the opposite direction, whereby the carrier can be maintained in a substantially rigid linear position when the boom machine is fully extended but bent back upon itself when the boom machine is retracted.

Heretofore, the track assemblies have been supported on the telescopic sections by complicated and expensive support members and when mounted on the outside of the boom, the track assemblies are likely to become damaged. The object of the present invention is to provide a structure that overcomes the problems inherent with the prior art structures.

After considerable research and experimentation, the carrier track assembly of the present invention has been devised wherein the carrier track is not only wholly contained within the telescopic boom sections but also supported by the fluid cylinder during the extension and retraction of the boom sections. By this construction and arrangement, the carrier track and associated hoses and cables are protectively housed within the boom sections, and the fluid cylinder performs the two-fold function of extending and retracting the boom sections and providing a support for the carrier track.

FIG. 1 is a side elevational view of an extensible and retractable boom machine having an aerial work platform mounted on the outermost end of a telescopic boom section, and employing the carrier track assembly of the present invention;

FIG. 2 is a side elevational view of the boom sections in the retracted position;

FIG. 3 is an enlarged side elevational view of the boom sections illustrated in FIG. 2, the drawing figure consisting of two portions which are joined longitudinally on the match line X-X;

FIG. 4 is a side elevational view of the boom sections in the extended position, the drawing figure consisting of two portions which are joined longitudinally on the match line Y-Y;

FIG. 5 is a view taken along line 5--5 of FIG. 3;

FIG. 6 is a view taken along line 6--6 of FIG. 3;

FIG. 7 is a view taken along line 7--7 of FIG. 3;

FIG. 8 is a view taken along line 8--8 of FIG. 3;

FIG. 9 is a view taken along line 9--9 of FIG. 3; and

FIG. 10 is a view taken along line 10--10 of FIG. 2.

Referring to the drawings and more particularly to FIG. 1, by way of example an extensible and retractable boom machine is illustrated in which the carrier track assembly of the present invention is adapted to be employed. The machine comprises a self-propelled steerable vehicular base 1 having a turntable 2 on which is mounted a horizontally turnable body portion 3. A counterweight 5 is connected to one end of the body portion 3, and parallel linkages 6 are pivotally connected at their lower ends to the body portion 3, and at their upper ends to a frame member 7 to which the base section 8 of the boom is pivotally connected as at 9. A first luffing cylinder 10 is provided between the body portion 3 and the linkages 6, and a second luffing cylinder 11 is provided between the frame member 7 and the base section 8, whereby the boom can be moved to various positions within a vertical plane. An extensible and retractable boom section 12 is telescopically received within the base section 8 and the telescopic movement of the boom section is effected by a fluid cylinder 13 mounted within the base section 8 and a piston rod 14 extending from the cylinder 13 and having its outer end fixed to the boom section 12. An aerial platform 15 is connected to the end of the boom section 12 and includes conventional controls for moving and steering the vehicular base 1, the luffing and sluing of the linkages 6 and boom base section 8, and the extension and retraction of the boom section 12, whereby a worker on the platform can control the position and reach of the telescopic boom assembly relative to an obstruction 16 in the vicinity of the work area.

As will be seen in FIGS. 3 and 5, the various hoses and cables 17 for transmitting power to the aerial work platform 15 extend into the base section 8 from the inner end thereof and are supported by a shelf 18 having convergent side walls 19 welded to the cylinder 13. The hoses and cables 17 extend through a plurality of longitudinally spaced channels 20, bolted as at 21 to the shelf 18, to thereby retain the hoses and cables 17 on the shelf 18.

Referring to FIGS. 3, 4 and 8, it will be seen that after the hoses and cables 17 pass through the channels 20, they extend into and are supported by a conventional flexible carrier track 22 of the type disclosed in U.S. Pat. No. 4,129,277 to Tenniswood. The track 22 has its inner end secured to the shelf 18 as at 23 and its outer end secured as at 24 to the inner end of the next adjacent boom section 12, the track 22 having a reversely bent or bight portion 25, whereby when the boom section 12 is extended, as shown in FIG. 4, the track 22 and associated hoses and cables 17 are supported on the shelf 18 secured to the cylinder 13. When the boom section 12 is retracted, as shown in FIG. 2, the track 22 is folded back on itself, to thereby shorten the effective length of the hoses and cables 17.

In order to prevent possible sagging of the track 22 when the boom section 12 is retracted, as will be seen in FIGS. 3, 6 and 7, an elevated support member 26 is provided at a position between the inner end of the base section 8 and the track connection 23. The support member comprises an inverted channel member having a web portion 27 upon which the track 22 rests, depending side walls 28, 29 secured to the edge portions of the shelf 18, and front and rear inclined wall portions 30, 31, respectively.

To complete the support of the hoses and cables 17 within the boom sections 8 and 12, as will be seen in FIGS. 2, 3 and 10, a plurality of longitudinally spaced channels 32, similar to channels 20, are bolted or otherwise suitably fastened to the top wall of boom section 12. The hoses and cables 17 extend through the channels 32 to the work unit, such as, the aerial platform 15, on the end of the boom section 12.

The remaining structure of the telescopic boom assembly is well understood by those skilled in the art and forms no part of the present invention, it being understood that the cylinder 13 remains fixed during the extension and retraction of boom section 12 and having its inner end secured to the inner end of the base section 8 as at 33, as shown in FIG. 3, and the free end of the piston rod being connected as at 34 to the boom section 12. Additionally, as will be seen in FIGS. 5 and 10, suitable slide bearings 35 are provided between the boom sections 8 and 12 to facilitate the telescopic movement of the boom section 12.

From the above description, it will be readily apparent to those skilled in the art that the carrier track 22 and associated hoses and cables 17 are protectively housed within the boom sections 8 and 12 during the telescopic movement of the boom section 12, and the fluid cylinder 13 is employed for not only extending and retracting the boom section 12 but also as a support for the carrier track when the boom section is in an extended and retracted position.

The carrier track 22 thus consists of a bottom flight portion and a top flight portion joined by a reversely bent or rolling bight portion 25. As the boom section 12 is extended the rolling bight portion 25 moves outwardly away from its inner end 23 and away from the elevated support member 26, during which the length of the bottom flight portion increases while the length of the top flight portion decreases. During this boom extension movement the top flight portion slides outwardly over the top of web portion 27 of support member 26 and the outer end of the carrier track will eventually pass over the top of web portion 27. After this, the length of the top flight portion will be reduced to a length that is self supporting without appreciable sagging or with no sagging, and the bottom flight portion continues to increase in length and be laid in supported linear position on the shelf 18 in a direction outwardly from and away from elevated support member 26. In the fully extended position of the boom the bottom flight portion comprises substantially the full length of the carrier track, as shown in FIG. 4, and in this position the carrier track is substantially fully supported on the shelf 18 outwardly from and away from the elevated support member 26.

Flexible carrier track 22 is of a construction that is readily available from different manufacturers and may be constructed of metal or of plastics for greater saving in weight. The track links are constructed to pivot relative to each other in one direction but not in the opposite direction so that the top flight is somewhat self supporting over short distances. Some track constructions will sag more than others in the retracted position of the boom and while a single elevated support member 26 is shown in the drawings, it is understood that two or more support members 26 may be provided, such as, for example, two additional elevated support members 26 connected over top of the channels 20 in FIG. 2 on each side of the single elevated support member 26 shown.

The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof but it is recognized that various modifications are possible within the scope of the invention claimed.