Patent Publication Number: US-2007098536-A1

Title: Extendable telescoping boom and method of manufacturing

Description:
PRIORITY STATEMENT  
      This application claims priority to U.S. Provisional Patent Application No. 60/731,767 filed Oct. 31, 2005, herein incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION  
      This invention relates to an extendable telescoping boom and method of manufacturing. This invention will be shown as an extendable telescoping boom and lift assembly that can be attached to a towing vehicle and used to lift and tow other vehicles. However, the extendable telescoping boom and method of manufacturing can be used with any application requiring an extendable telescoping boom.  
      Telescoping booms are common in industry for creating a long boom which can store and travel in a shorter space. Typically, the boom sections are greased with a lubricant so that the multiple sections can slide inside one another easily with reduced friction. Additionally, some telescoping booms have external mechanisms welded or affixed to the boom sections to hold wear pads which allow wear pads to reduce the friction between the sliding telescoping parts. However, attaching external mechanisms to hold the wear pads between the nesting, telescoping parts, creates a large clearance gap between the two or more parts which nest immediately inside one another. This large clearance gap allows dirt and other debris to gather between the telescoping parts and cause friction and premature wear of the parts.  
      In light of the foregoing problems with telescoping booms, it is desirable to have an improved extendable telescoping boom and method of manufacturing.  
      Therefore, the primary feature or advantage of the present invention is to provide an improved extendable telescoping boom and method of manufacturing.  
      Another feature or advantage of the present invention is the provision of a telescoping boom which provides smaller clearance between boom elements or parts.  
      Another feature or advantage of the present invention is an extendable telescoping boom which is easier to manufacture than current designs.  
      Still another feature or advantage of the present invention is an extendable telescoping boom which can be more precisely manufactured due to tighter tolerances.  
      Yet another feature or advantage of the present invention is an extendable telescoping boom which has a better fit between boom sections.  
      A further feature or advantage of the present invention is an extendable telescoping boom with wear pads that are cheaper to make and easier to replace.  
      A further feature or advantage of the present invention is a method of manufacturing an extendable telescoping boom.  
      A still further feature or advantage of the present invention is a provision of an extendable telescoping boom which is economical to manufacture, durable in use and efficient in operation.  
      One or more of these and/or other features or advantages of the invention will be apparent from the specification and claims that follow.  
     BRIEF SUMMARY OF THE INVENTION  
      One or more of the foregoing features or advantages may be achieved by an extendable telescoping boom having a first boom section with an opening at an end and running linearly inside the first boom section, a second boom section which slideably nests within the opening of the first boom section and slides linearly within the opening and one or more wear pads attached within one or more sunken pockets inside the first boom section and arranged to allow the second boom section to slide linearly inside the first boom section. Alternatively, the one or more wear pads may be attached within one or more sunken pockets outside of the second boom section and arranged to allow the second boom section to slide linearly inside the first boom section. Additionally, the one or more wear pads may be attached within one or more sunken pockets inside the first boom section and within one or more sunken pockets outside of the second boom section and arranged to allow the second boom section to slide linearly inside the first boom section. Any number of boom sections nested together in similar fashion may be used.  
      One or more of the foregoing features or advantages may also be achieved by a lifting vehicle having an extendable telescoping boom which has nestable sliding sections with sunken pockets and wear pads attached within the sunken pockets to guide the sliding of the nested parts to extend and retract the telescoping boom.  
      One or more of the foregoing features or advantages may also be achieved by a method of making a telescoping boom by creating one or more sunken pockets inside a first boom section, attaching one or more wear pads in the one or more sunken pockets in the first boom section, creating one or more sunken pockets outside of the second boom section, attaching one or more wear pads in the one or more sunken pockets in the second boom section, and inserting the second boom section inside the first boom section so that the second boom section slides linearly inside the first boom section gliding on the one or more wear pads. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES AND DRAWINGS  
       FIG. 1  is an isometric view of one embodiment of the current invention integrated onto a towing vehicle boom lift assembly.  
       FIG. 2  is an exploded isometric view of multiple sections of one embodiment of an extendable telescoping boom assembly.  
       FIG. 2A  is an enlarged view of a portion of  FIG. 2 .  
       FIG. 2B  is an enlarged view of a portion of  FIG. 2 .  
       FIG. 2C  is an enlarged view of a portion of  FIG. 2B .  
       FIG. 3  is a plan view of one embodiment of an extendable telescoping boom.  
       FIG. 3A  is an enlarged view of a portion of  FIG. 3 .  
       FIG. 4  is a sectional view along lines  4 - 4  of  FIG. 3 .  
       FIG. 4A  is an enlarged view of a portion of  FIG. 4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       FIG. 1  shows one embodiment of a tilt recovery auto lift system assembly  10  of the current invention. The lift system  10  is a device which mounts to a towing vehicle (not shown) and connects to and lifts a vehicle which is to be towed (not shown). A hydraulic cylinder assembly (not shown) for tilting a boom  14  allows the boom  14  to be raised and lowered, for use and stowing. The current invention is shown and described as an auto lift system, however the current invention can be used on any telescoping boom assembly, such as cranes, lifts, elevators, and the like.  
       FIG. 1  shows the lift system  10  with the boom assembly  14  in multiple positions. The boom  14  is a telescoping boom assembly. In addition, the lift system assembly  10  generally comprises a vehicle towing attachment assembly  12 . The vehicle towing attachment assembly  12  preferably has a kingpin for attaching to a towing vehicle (not shown) at a fifth wheel plate of a road tractor. The preferred towing vehicle attachment assembly  12  is similar that shown in U.S. Pat. Nos. 5,823,735 and 6,036,428 and application Ser. No. 11/216,266 for Kooima, which are herein incorporated by reference in their entirety. However, any towing vehicle attachment assembly  12  which allows the tilt recovery auto lift system assembly  10  of the current invention to be attached to a towing vehicle will work with the current invention. In addition, the boom assembly  14  can be used for any device requiring an extendable boom, not just for towing devices.  
      This embodiment of the invention also has a boom lift assembly  16  which attaches to a boom lift assembly mounting frame  17  and preferably uses one or more vertical hydraulic lift cylinders (not shown) for raising and lowering the boom lift assembly  16  and the boom assembly  14 . The boom assembly  14  pivots at the boom pivot point  30  for stowing.  
      The telescoping boom assembly  14 , as shown in the figures, has three sections. A first boom section  18 , a second boom section  20 , and a third boom section  22 . As shown in the figures, the third boom section  22  fits inside the second boom section  20 , which, in turn, fits inside the first boom section  18 . Preferably, a hydraulic cylinder is used for extending and retracting these boom sections  18 ,  20  and  22  within one another. However, any method or device can be used for extending the boom assembly  14 .  
       FIG. 2  shows an exploded view of one embodiment of the boom assembly  14 . Shown in  FIG. 2  and expanded in  FIGS. 2A, 2B  and  2 C are a number of wear pads  24  attached within sunken pockets  26 . In this embodiment, the wear pads  24  are preferably constructed from nylon, brass, rubber, Teflon, polyethylene, or etc. and are used to make the sections  18 ,  20 ,  22 , slide easier inside one another and give a surface to wear that can be readily replaced. The sunken pockets  26  and wear pads  24  are located so that as the third boom section  22  enters the inside of the second boom section  20  and the second boom section  20  enters the inside of the first boom section  18 , the wear pads, which extend above the sunken pockets  26  do not interfere with the wear pads on the mating-telescoping section  18 ,  20 ,  22 , as best seen in  FIGS. 2 and 3 . Additionally, the wear pads  24  located on the upper portion of the third boom section  22  and the second boom section  20  nearest the first boom section  18  are located on outward edges of the respective boom sections  20 ,  22  to not only allow wear and guiding assistance along the upper and lower portions of the boom sections  18 - 22 , but also to allow lateral wear and guiding assistance between the sections  18 - 22 .  FIGS. 3 and 3 A also show pocket lobes  28  which are part of the sunken pocket  26  which extends within the surface of the boom sections  18 - 22 . Pocket lobes  28  come from overrun on milling the pocket  26  with a round cutter. This overrun allows for square corner wear pads  24  to be used and fitted into the pocket  26 . The lobes  28  are not necessary in the pocket  26 . It is preferred that the wear pads  24  fit snugly into the pockets  26 . Any shape of wear pad  24  and pocket  26  is allowable.  
      Preferably the wear pads  24  can stay in the pockets  26  with a friction fit and then the mating parts  18 ,  20 ,  22  will hold them in place after assembly of the boom assembly  14 . However other methods can be used to hold the wear pads  24  in place, including, but not limited to, adhesives, mechanical fasteners and etc.  
       FIGS. 4 and 4 A show how the sunken pockets  26  and the wear pads  24  are preferably located in the boom sections  18 - 22 . As can be seen in these figures, the sunken pocket  26  can be milled, stamped, molded, etched and etc. into the respective boom sections  18 - 22  to allow the wear pads  24  to be affixed within the sunken pocket. As best seen in  FIG. 4A , a clearance gap  32  is required between the boom sections  18 - 20  and  20 - 22 . Having a clearance gap  32  is common in the art with telescoping boom sections. However using a sunken pocket  26  with wear pads  24  allows the clearance gap  32  to be reduced creating better tolerance boom assemblies  14 . As best seen in  FIGS. 2B and 2C , the wear pads  24  located on the end of the third boom section  22  which enters into the second boom section  20 , are located on the outer lateral edge of the boom section  22 . This allows for guideability and wear resistance both vertical and lateral when the boom sections  18 - 22  are extended and contracted.  
      It is noted that any number of boom sections  18 - 22  can be used with the current invention. Additionally, any number of sunken pockets  26  and wear pads  24  can be used, and can be used in any arrangement on the boom sections  18 - 22 . It is also preferred that the boom sections  18 - 22  be constructed of rigid material, such as steel, to allow the boom assembly  14  to expand and contract while remaining strong enough for the boom&#39;s  14  intended purpose.  
      A pocket cut out  26  of the boom section  18 - 22  to hold the wear pad  24  does several things. It allows the boom sections  18 - 22  to be fitted together with a much smaller clearance gap  32  between boom elements  18 - 22 . It allows easier manufacturing methods of the boom assembly  14 . It allows a more precise method of manufacturing, which allows better fit between boom sections  18 - 22  and, it allows introducing wear pads  24  that are cheaper to make and easier to replace than traditional wear pads. The wear pads  24  can simply be pieces of the wear pad  24  material which fit the pockets  26 .  
      Because the pocket  26  is cut out or counter sunken into the boom section  18 - 22 , there is no need to weld or provide an external mechanism to hold the wear pads  24 . Such mechanisms, if applied take up considerable amount of room and have to be allowed for when planning for the wear thickness of the wear pad  24 . This can amount to doubling the gap  32  needed between boom sections  18 - 20  and  20 - 22 . Also, if the wear pad  24  is made with a “nutsert” or other fastening method imbedded into the wear pad  24  surface, that too has to be considered for the wear portion of the wear pad  24 , may double the spacing between the boom sections, and costs more to make which is undesirable.  
      When milling the pocket  26  for the wear pad  24 , more precision can be maintained so the fit of the boom sections  18 - 22  will be more precise which will allow easier fit-up and more precise extension of the boom  14 . The pocket  26  can be provided by other means than milling, such as , but not limited to laser cutting, or cutting by any method completely through the material, then adding a back-up plate (not shown). However, in multiple telescoping boom sections, this would defeat the purpose of milling the pocket  26  through only part of the material.  
      In the embodiment illustrated, the wear pads  24  are made of moly filled nylon which is ⅜″ thick. The pocket  26  in the boom sections  18 - 22  are ⅛ 41  deep, which leaves ¼″ of wear pad  24  exposed. This ¼″ can be completely worn down before the boom sections  18 - 22  contact one another. The gap  36  in the boom sections  18 - 22  is only ¼″ giving the maximum wear surface for the amount of gap  32  needed. The boom sections  18 - 22  are preferably made so the pads  24  contact the surfaces of the boom section  18 - 22  as extreme to the strongest cross section as possible, i.e. where the vertical boom section mates with the horizontal section of the boom. This will allow for greatest strength where the wear pad  24  comes in contact with the boom section  18 - 22 . This will prevent the boom section  18 - 22  from ‘oil canning’ in the area of contact. The pad also preferably ‘overhangs’ the inner boom section to give the boom a side-to-side wear plate, the wear pad  24  making contact with the outer boom section instead of the metal-to-metal wear between boom sections.  
      The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives.