Abstract:
A basket removably attachable to a support arm extending laterally outwardly from a helicopter, comprises a frame structure having a bottom support surface and a top surface joined together in an axially adjustable relationship. An opening is defined in the top surface of the frame structure for providing access to the bottom support surface. The frame structure is displaceable between collapsed and erected positions for selectively reducing and increasing its height, whereby the basket can be carried in its collapsed position and, once on site, extended to its erected position for safely receiving at least one operator.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the servicing of elevated cables or installations, such as high voltage power lines and, more particularly, pertains to a new basket structure suited for supporting workmen during servicing operations. 
     2. Description of the Prior Art 
     Over the years, various helicopter portable basket structures have been developed for servicing elevated cables or installations, such as high voltage power transmission lines. For instance, U.S. Pat. No. 4,478,312 issued on Oct. 23, 1984 to Kurtgis, U.S. Pat. No. 4,422,528 issued on Dec. 27, 1983 to Patterson and Canadian Patent laid-open application No. 2,055,639 filed on Nov. 15, 1991 in the names of De Forges de Parny et al. all disclose a basket structure suspended on rope slings from a helicopter by means of an appropriate lifting harness system. Such arrangements, wherein the basket structure is supported underneath the helicopter, suffer from several disadvantages. For instance, in the case of a malfunctioning of the helicopter implying an emergency landing, the basket structure has to be dropped to permit landing of the helicopter. Furthermore, when the basket structure is disposed at the end of downwardly depending slings as mentioned hereinbefore, the helicopter pilot is not in a position to accurately assess the position of the basket structure, thereby rendering the installation thereof on elevated cables quite arduous and time consuming. 
     Accordingly, attempts have been made to overcome the above mentioned drawbacks. For example, U.S. Pat. No. 5,328,133 issued on Jul. 12, 1994 to Charest et al. discloses a basket structure which is removably mounted at one end of a support arm extending laterally outwardly of a helicopter. 
     Although the system described in the above mentioned patent constitutes an improvement over previously known helicopter basket carrying systems, it has been found that there is a need for a new basket structure adapted to be carried in a compact manner by a helicopter in order to provide additional clearance to the rotor blades of the helicopter, while still providing the required clearance above ground level during take-off and landing operations. 
     SUMMARY OF THE INVENTION 
     It is therefore an aim of the present invention to provide a basket adapted to be transported in a compact manner laterally outwardly of a helicopter. 
     It is also an aim of the present invention to provide a basket adapted to be traversed over obstacles depending from elevated cables. 
     It is a further aim of the present invention to provide a basket which is relatively easily installable on elevated cables. 
     Therefore, in accordance with the present invention, there is provided a basket adapted for attachment to a support arm extending laterally outwardly from a helicopter used to carry the basket to elevated cables or installations, comprising a container structure having a bottom support surface and an open top end for providing access to the bottom support surface, the container structure being displaceable between a collapsed position wherein the container structure has a reduced height and an erected position wherein the container structure has a full height. 
     In accordance with another general aspect of the present invention, there is provided a basket adapted for attachment to a support arm extending laterally outwardly from a helicopter, comprising a frame structure having a bottom support surface and a top surface joined together in an axially adjustable relationship, the top surface defining an opening for providing access to the bottom support surface, the frame structure being displaceable between collapsed and erected positions for selectively reducing and increasing axial dimensions thereof, whereby the basket can be carried in the collapsed position and, once on site, extended to the erected position for safely receiving at least one operator. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof, and in which: 
     FIG. 1 is an end elevational view of a collapsible basket structure removably mounted at one end of a support arm extending laterally outwardly from a helicopter in accordance with a first embodiment of the present invention; 
     FIG. 2 is a side elevational view of the collapsible basket structure illustrated in a collapsed position thereof and temporarily supported on a pair of laterally spaced-apart parallel elevated cables by means of a pair of front and rear articulated extendable and retractable support arms; and 
     FIG. 3 is a side elevational view of the collapsible basket structure shown in an erected position thereof and supported on the elevated cables by means of four railway wheel support arms. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now referring to the drawings, there is shown a collapsible basket structure  10  adapted to be detachably mounted at the end of a support arm A extending laterally outwardly of a helicopter H used to carry the collapsible basket  10  to and away from elevated installations, such as high voltage lines. 
     The collapsible basket  10  generally comprises a rectangular inner framework  12  adapted to be slidably received in a telescopic fashion within an associated rectangular outer framework  14 . It is understood that the external dimensions of the inner framework  12  are slightly less than the internal dimensions of the outer framework  14 . 
     As seen in FIGS. 2 and 3, the inner framework  12  includes a rectangular top frame structure  16  and a rectangular bottom frame structure  18  rigidly interconnected to each other through four upstanding corner posts  20 . A rectangular floor or bottom support surface  22  is mounted to the bottom frame structure  18 . The bottom support surface  22  is preferably made of a corrugated plate of rigid material. Protective grids  24  are provided about the perimeter of the inner framework  12  to prevent equipment from falling out from the inside of the inner framework  12 . 
     Similarly, the outer framework  14  is provided with rectangular top and bottom frame structures  26  and  28  rigidly joined by four upstanding corner posts  30 . The top frame structure  26  defines a rectangular top opening to provide access to the bottom support surface  22  of the inner framework  12 , whereas the bottom frame structure  28  defines a rectangular bottom opening which is slightly greater than the external rectangle formed by the upstanding corner posts  20  of the inner framework  12 , thereby allowing the inner framework  12  to be selectively vertically moved into and out of the outer framework  14  through the rectangular bottom opening thereof. 
     All the parts of the bottom and outer frameworks  12  and  14  are preferably made of welded metallic tubing and plates. 
     As seen in FIGS. 1 and 2, the collapsible basket  10  can be locked in a collapsed position wherein the inner framework  12  is retracted within the outer framework  14  and held in place by means of a pair of opposed catch members  32  extending respectively frontwardly and rearwardly from the top frame structure  16  of the inner framework  12  for engaging subjacent portions of the top surface of the top frame structure  26  of the outer framework  14 . Each catch member  32  consists of a rigid flat plate pivotally mounted at  33  on the top surface of a cross flange member  34  forming part of the top frame structure  16  of the inner framework  12 . 
     the collapsible basket  10  can be readily unlocked from its collapsed position by manually pivoting the catch members  32  to an idle position (see FIG. 3) wherein the catch members  32  extend in a generally crosswise direction relative to the collapsible basket  10  so as to overly respective flange members  34 , thereby clearing the top surface of the top frame structure  26 . This operation may be facilitated by previously slightly lifting the inner framework  12  so as to elevate the catch members  32  above the top surface of the top frame structure  26  in order to eliminate the friction forces which are induced when the catch members  32  are rotated while still being in contact with the subjacent portions of the top frame structure  26  of the outer framework  14 . The inner framework  12  can be manually lifted via a rope or handle (not shown) attached to the bottom support surface  22 . 
     Once the catch members  32  have been pivoted inwardly to their respective idle positions, as described hereinbefore, the collapsible basket  10  can be displaced to an erected position thereof for the purpose of safely receiving at least one workman therein. This is achieved by lowering the inner framework  12  to an extended position wherein the inner framework  12  depends downwardly from the outer framework  14 , as seen in FIG.  3 . 
     A pair of opposed inner shoulders  36  extend respectively along the front inner surface and the rear inner surface of the rectangular bottom frame structure  28  of the outer framework  14  to form a resting surface against which the undersurface of corresponding flange members  34  may rest to retain the inner framework  12  in its lowered suspended position relative to the outer framework  14 . 
     As seen in FIG. 1, the collapsible basket  10  is locked in its collapsed position when installed at the end of the support arm A of the helicopter H. This advantageously provides additional clearance between the basket  10  and the rotor blades B of the helicopter H, while still providing the clearance between the skids S of the helicopter H and the undersurface of the basket  10  which is required to ensure that the basket  10  will not interfere with the landing of the helicopter H. Indeed, the bottom of the basket  10  has to be at a higher elevation than that of the skids S so that the helicopter may land at any time while still carrying the collapsible basket  10 . The additional clearance obtained between the rotor blades B and the collapsible basket  10  facilitates the manoeuvres which the helicopter pilot has to accomplish in order to place the basket  10 , for instance, under a pair of laterally spaced-apart parallel cables C so that the basket  10  can be subsequently suspended therefrom as will be explained hereinafter. This operation necessitates that the helicopter H be displaced sideways towards the cables C with the rotor blades B being disposed above the cables C and the collapsible basket  10  thereunder, whereby it is extremely advantageous to be able to maximize the spacing between the top of the collapsible basket  10  and the rotor blades B. By using a collapsible basket in accordance with the present invention, it becomes possible to anchor the basket at a lower level with respect to the helicopter H, thereby providing additional clearance between the basket and the rotor blade B, while still maintaining the required clearance between the basket and the skids S of the helicopter H. 
     As seen in FIG. 1, the collapsible basket  10  is detachably mounted to the support arm A of the helicopter H via an inverted L-shaped support member  38  detachably secured to a helicopter side of the outer framework  14 . The inverted L-shaped support member  38  includes an elongated vertical tubular portion  40  adapted to be slidably inserted within a pair of vertically aligned U-shaped brackets  42  extending laterally outwardly from the helicopter side of the outer framework  14 . According to one embodiment of the present invention, one U-shaped bracket  42  is secured to the top frame structure  26  and the other to the bottom frame structure  28  with both U-shaped brackets  42  being located midway between the front and rear ends of the collapsible basket  10 . A lock pin  43  is transversely inserted through each U-shaped bracket  42  and through the vertical tubular portion  40  of the inverted L-shaped support member  38  to prevent axial removal of the latter from the U-shaped brackets  38 . A hook  44  is aligned with the U-shaped brackets  42  and extends laterally outwardly from an undersurface of the bottom frame structure  28  of the outer framework  14  for engagement within the open bottom end of the elongated vertical tubular portion  40  of the inverted L-shaped support member  38  to prevent the same from pivoting outwardly away from the helicopter side of the outer framework  14 . 
     The inverted L-shaped support member  38  further includes a horizontal tubular portion  46  to which a cross member  48  is welded or otherwise secured so as to extend generally in the longitudinal plane of symmetry of the collapsible basket  10 . A carrying member  50  having a generally inverted V-shaped configuration is secured at opposed lower ends thereof to respective opposed end portions of the cross member  48 . A channel (not shown) extending in a direction parallel to the horizontal tubular portion  46  of the inverted L-shaped support member  38  and having a square or rectangular cross-section is defined at an apex  52  of the inverted V-shaped carrying member  50 . The channel is opened towards the bottom so that the carrying member  50  may be suspended in a stable manner on the support arm A of the helicopter H so as to prevent rotational movement of the collapsible basket  10  about the support arm A. Furthermore, it is pointed out that the apex  52  of the carrying member  50  is substantially in vertical alignment with the center of gravity of the collapsible basket  10  to further improve the stability of the basket  10  during transportation. Abutments (not shown) are provided on the support arm A to prevent linear movement of the basket  10  along the support arm A. 
     The collapsible basket  10  further comprises two pairs of railway wheel support arms  54  and  56  disposed on respective opposed sides of the outer framework  14  for carrying railway wheels  58  rotatably mounted thereon. The wheels  58  may be motorized or not and are configured and disposed to ride over a pair of laterally spaced-apart parallel elevated cables C, as seen in FIG.  3 . 
     The first pair of railway support arms  54  is disposed on the helicopter side of the outer frame  14 . As seen in FIG. 2, each railway support arm  54  includes first and second elongated portions  60  and  62  pivotally connected to one another via a pivot pin  64 . The first elongated portion  60  of each railway wheel support arm  54  is inserted in a pair of vertically aligned brackets (not shown) extending laterally outwardly from the helicopter side of the outer framework  14  and removably secured thereto by means of lock pins (not shown). Each railway wheel support arm  54  further includes a lock pin  66  which can be transversally inserted through the first and second elongated portions  60  and  62  to lock the railway wheel support arm  54  in a straight line configuration. 
     The second pair of railway support arms  56  are disposed on the opposite side of the outer frame  14 . As seen in FIG. 3, each railway support arm  56  includes first and second elongated portions  68  and  70  pivotally connected to one another via a pivot pin  72 . Each railway wheel support arm  56  further includes a lock pin  73  which can be transversally inserted through the first and second elongated portions  68  and  70  to lock the railway wheel support arm  56  in a straight line configuration. The first elongated portion  68  of each railway wheel support arm  56  is articulated at the bottom end thereof to the bottom portion of the corresponding corner posts  30  of the outer framework  14  via a universal joint  74 , or the like. This allows each railway wheel support arm  56  to be folded down along the side of the outer framework  14  during transportation of the collapsible basket  10  by the helicopter H, as seen in FIGS. 1 and 2. Each railway wheel support arm  56  can be locked in an upstanding position, as seen in FIG. 3, by first pivoting the railway wheel support arm  56  within a U-shaped bracket  76  secured to the top end portion of the associate corner post  30  and by subsequently inserting a lock pin  78  through the U-shaped bracket  76  and the railway wheel support arm  56 . 
     The collapsible basket  10  further includes a pair of front and rear extendable/retractable arms  80  and  82  respectively pivotally mounted to a front bottom extension  84  and a rear bottom extension  86  of the outer framework  14 . More specifically, the front extendable/retractable arm  80  is mounted for rotation about a pivot  88  between vertical and horizontal positions, as indicated by arrow  90  in FIGS. 2 and 3. Similarly, the rear extendable/retractable arm  82  is mounted for rotation about a pivot  92  between vertical and horizontal positions, as indicated by arrow  94  in FIGS. 2 and 3. The front and rear extendable/retractable arms  80  and  82  are each attached to one end of a cable  96  which is attached at the other end thereof to the outer framework  14  in order to limit the downward pivot of the front and rear extendable/retractable arms  80  and  82  to 90 degrees to the vertical. The front extendable/retractable arm  80  can be held in its upstanding vertical position by means of a retention arm  98  extending frontwardly from the top frame structure  26  of the outer framework  14  and having at a distal end thereof a U-shaped bracket  100  through which a lock pin  102  may be removably transversally inserted after having pivoted the front extendable/retractable arm  80  upwardly into the U-shaped bracket  102 . Similarly, the rear extendable/retractable arm  82  can be held in its upstanding vertical position by means of a retention arm  104  extending rearwardly from the top frame structure  26  of the outer framework  14  and having at a distal end thereof a U-shaped bracket  106  through which a lock pin  108  may be removably transversally inserted after having pivoted the rear extendable/retractable arm  82  upwardly into the U-shaped bracket  106 . 
     The front and rear extendable/retractable arms  80  and  82  are each provided at a respective distal end thereof with an axle  110  at opposed ends of which a pair of wheels  112  are rotatably mounted. As seen in FIG. 2, the wheels  112  are adapted to ride on a given pair of laterally spaced-apart parallel elevated cables C. 
     As indicated by arrows  114  in FIG. 2, the front and rear extendable/retractable arms  80  and  82  may be extended or retracted to vary the length thereof in order to lower or raise the collapsible basket  10  with respect to the elevated cables C. Furthermore, as depicted in FIGS. 2 and 3, the front and rear extendable/retractable arms  80  and  82  can be rotated as per arrow  116  upon themselves to allow the wheels  110  to be placed on a pair of spaced-apart cables C from below, as will be described hereinafter. 
     According to a preferred embodiment of the present invention, the extendable/retractable arms  80  and  82  each consist of a hydraulic cylinder having a piston rod equipped with a swivel for allowing the axle  110  connected therewith to be rotated about the piston rod. In this case, a motor  118  can be mounted on the front bottom extension  84  to power the front and rear extendable/retractable arms  80  and  82 . 
     Furthermore, it is noted that the tubular structure of the inner and outer frameworks  12  and  14  can advantageously be used as an oil reservoir. 
     In operation, the collapsible basket  10 , which is in its collapsed position with the second pair of railway wheel arms  56  folded down along one side thereof, is suspended from the support arm A of the helicopter H via the carrying member  50 , as illustrated in FIG.  1 . Then, the collapsed basket  10  is carried to a length of elevated cables where an operation has to be carried out. The helicopter H approaches the elevated cables C sideways so as to place the horizontal tubular portion  46  of the inverted L-shaped support member  38  above the cables with the collapsed basket  10  underlying the cables C. 
     Then, the horizontal tubular portion  46  which extends crosswise relative to the subjacent pair of laterally spaced-apart cables C is lowered onto the cables C by the helicopter H. As seen in FIG. 1, a V-shaped guide  120  can be fixed to the undersurface of the horizontal tubular portion  46  of the inverted L-shaped support member  38  to ensure proper positioning of the horizontal tubular portion  46  on the cables C. Once the horizontal tubular portion  46  properly rests on the cables C, the support arm A is lowered by the helicopter H so as to move the support arm A out of engagement with the carrying member  50 . 
     Thereafter, the helicopter H moves sideways away from the cables C so as to withdraw the support arm a from between the carrying member  50 . The helicopter H is then brought back down onto the ground and a platform (not shown) is removably mounted to the helicopter H for allowing an operator to take place thereon laterally outwardly of the helicopter H. Once this operation has been completed, the platform is carried laterally adjacent to the suspended basket  10  to allow the operator to place the wheels  112  onto the cables C. This is accomplished by first pivoting the front and rear extendable/retractable arms  80  and  82  to their respective upstanding positions, second rotating the front and rear extendable/retractable arms  80  and  82  as per arrows  116  about their respective longitudinal axes so as to place the axles  110  parallel to the cables C, third extending the extendable/retractable arms  80  and  82  between the cables in order to pass the axles  110  above the cables C, fourth rotating the front and rear extendable/retractable arms  80  and  82  as per arrows  116  about their respective longitudinal axes so that the axles  112  extend transversally of the cables C with the wheels  112  in vertical alignment with the corresponding underlying cables C, and fifth retracting the extendable/retractable arms  80  and  82  to lower the wheels  112  on the cables C. 
     After the wheels  112  have been positioned on the cables C as described above, the extendable/retractable arms  80  and  82  are further retracted in order to lift the collapsible basket  10  and, thus, raise the horizontal tubular portion  46  of the inverted L-shaped support member  38  above the cables C. In this position the collapsed basket  10  is suspended from the cables via the front and rear extendable/retractable arms  80  and  82 , as seen in FIG.  2 . 
     Thereafter, the inverted L-shaped support member  38  is detached from the outer framework  14  and placed on the platform (not shown). The basket  10  is then erected and the operator transferred therein. Subsequently, the second pair of railway wheel support arms  56  are unfolded and secured in their respective upstanding positions. Then, the front and rear extendable/retractable arms  80  and  82  are extended so as to lower the railway wheel  58  onto the cables C. Once this operation has been accomplished, the front and rear extendable/retractable arms  80  and  82  are disengaged from the cables C and placed thereunder in their idle position. At this stage, the basket  10  is suspended from the cables C via the first and second pairs of railway wheel support arms  54  and  56 , as illustrated in FIG.  3 . The wheels  58  may be motorized to displaced the basket on the cables C. Alternatively, the basket  10  can be manually propelled. 
     When an obstacle, such as a hardware attached to the cables C is encountered, the front and rear extendable/retractable arms  80  and  82  can be used for traversing the collapsible basket  10  over the obstacle. This is accomplished by first positioning the front wheels  58  as close as possible to the obstacle, second positioning the wheels  112  of the front extendable/retractable arm  80  on the downstream side of the obstacle, third retracting the front extendable/retractable arm  80  so as to lift the front of the basket  10 , fourth pivoting the second portions of  62  and  70  of the front railway wheel support arms  56  and  58  outwardly so as to disengage the front wheels  58  from the cables C, fifth advancing the basket  10  on the cables C so as to place the front wheels  58  on the downstream side of the obstacle, sixth pivoting and locking the second portions  62  and  70  of the front railway wheel support members  56  above the cables, seventh retracting the front extendable/retractable arm  80  so as to lower the front wheels  58  onto the cables C, and finally placing the front extendable/retractable back to its idle position. The rear extendable/retractable arm  82  is used in a similar manner to pass the rear wheels  58  on the downstream side of the obstacle. 
     Finally, the basket  10  can be removed from the cables C by generally following the reversed steps required for installing the same onto the cables C.