Abstract:
Manual boom lift apparatus and method involve a base having three support legs, a fulcrum configured to fixedly mount the legs, a boom member detachably mounted on the fulcrum, the boom member including on either end a counterbalance arm configured for detachably mounting one or more counterweights and a lift arm configured for hoisting a load, the lift apparatus enabling lift and placement of the load by pivotal manipulation of the boom member. Assembly of the detachable boom lift apparatus components is performed on the work site (in situ) and involves removably pinning aligned hole pairs to join the components and filling one or more containers with ballast to act as counterweights to the hoisted load. The apparatus is lightweight and durable, is easy to transport through small openings and can be used in rooftop installations of heating, ventilation, air conditioning and refrigeration (HVAC/R) equipment.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Cranes are used for heavy lifting, but weigh several tons (since they typically use heavy counterweights) and typically are stationary, with a predefined range or so-called ‘reach.’ Some cranes are mounted on wheels, thus rendering them tow-able or even drivable, but they still suffer from the same weight and reach problems. Moreover, cranes are very expensive to own and operate. Forklifts have the same problems of high weight and cost, and suffer even more limited reach relative to their counterweighted base, but they are maneuverable. Neither cranes nor forklifts are lightweight and portable enough to be employed in rooftop installations.  
         [0002]     Auto shop engine pullers use hoists, e.g. cable and pulley systems, or hydraulics to meet medium load lifting needs. They are generally fixed in position and do not break down easily for transporting to a different work site. Moreover, such an engine puller typically has a negative range, i.e. its effective lift range is within the perimeter of its base&#39;s footprint.  
         [0003]     Rooftop installations, e.g. of heating/ventilation/air conditioning/refrigeration (HVAC/R), often require lifting of light to medium loads of less than approximately 1000 pounds. It is most often cost-prohibitive to do a rooftop installation or replacement, e.g. of an air conditioning unit, using a crane. A typical shop forklift weighs upwards of twelve tons, exceeding the load capacity of most rooftops. In any event, a crane would typically be required to lift the forklift onto the rooftop. Hydraulic/pneumatic lifts are heavy and difficult to transport. Moreover, a hydraulic/pneumatic lift requires power and/or a hydraulic/pneumatic source.  
       SUMMARY OF THE INVENTION  
       [0004]     Manual boom lift apparatus and method involve a base having three support legs, a fulcrum configured to fixedly mount the legs, a boom member detachably mounted on the fulcrum, the boom member including on either end a counterbalance arm configured for detachably mounting one or more counterweights and a lift arm configured for hoisting a load, the lift apparatus enabling lift and placement of the load by pivotal manipulation of the boom member. Assembly of the detachable boom lift apparatus components is performed on site (in situ) and involves removably pinning aligned hole pairs to join the components and filling one or more containers with ballast to act as counterweights to the hoisted load. The apparatus is lightweight and durable, is easy to transport through small openings and can be used in rooftop installations of heating, ventilation, air conditioning and refrigeration (HVAC/R) equipment.  
         [0005]     These and additional objects and advantages of the present invention will be more readily understood after consideration of the drawings and the detailed description of the preferred embodiment which follows. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1  is an isometric view in exploded assembly form of the invented apparatus in accordance with one embodiment of the invention, with the counterbalance weights shown only in phantom.  
         [0007]     Detail A corresponds with  FIG. 1 , but shows in enlarged fragmentary, assembled, isometric view the fulcrum mechanism that forms a part of the invented apparatus in accordance with one embodiment of the invention.  
         [0008]      FIG. 2  is a front elevation corresponding with  FIG. 1  but with the boom omitted for clarity.  
         [0009]      FIG. 3  is a side elevation corresponding with  FIG. 2 .  
         [0010]      FIG. 4  is an isometric view in exploded assembly form of the invented apparatus in accordance with a second embodiment of the invention, with the counterbalance weights shown only in phantom.  
         [0011]      FIG. 5  is an isometric view in exploded assembly form of the invented apparatus in accordance with a third embodiment of the invention, with the counterbalance weights shown only in phantom.  
         [0012]      FIG. 6  is a front elevation corresponding with  FIG. 5 , with the boom omitted for clarity.  
         [0013]      FIG. 7  is a side elevation corresponding with  FIG. 5 , but with the boom included, and with the counterbalance weights shown only in phantom.  
         [0014]      FIG. 8  is a flowchart illustrating the invented boom lift method of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]     The invented method and apparatus provide a low-cost, manual, portable, lightweight boom lift that lends itself to rooftop installations, at elevations above the rooftop of up to approximately ten feet, of light-to-medium loads up to approximately 1000 pounds. The apparatus is assembled by pivotally pinning, e.g. with one or more cotter keys, various relatively lightweight members together on site (in situ) and to charge the counterweight arm end of the boom lift opposite the lift arm also on site, thus greatly facilitating maneuverability in transport, employment and deployment. The counterweights preferably are water-chargeable containers. The boom lift leverages its load by a simple 2:1 mechanically advantaged boom lift manipulation atop its tripod support legs-and-wheels arrangement. Neither hydraulic nor pneumatic nor power conduits are required for operation. The lightweight extruded square-tubular and die-cast aluminum and steel materials and simple structural geometries render the apparatus very low cost. The apparatus is structured for ready break-down and thus has a relatively small footprint in use and an even smaller footprint in transit to and from a work site. These and other advantages will be more apparent from the detailed discussion below.  
         [0016]      FIG. 1  illustrates in isometric view the invented manual boom lift apparatus  10  in accordance with a first embodiment of the invention. Apparatus  10  includes a base  12  having three or more support legs  14 ,  16 ,  18 . It further includes a fulcrum mechanism  20  configured to fixedly mount support legs  14 ,  16 ,  18  in a tripod configuration, as shown. Apparatus  10  further includes a boom member  22  detachably and pivotally mounted on fulcrum mechanism  20 . Boom member  22  includes fore and aft respectively a counterweight arm  24  configured for detachably mounting one or more weights  26   b,    26   c,    26   d,    26   e,    26   f  (shown in phantom) and a lift arm  28  configured to hoist a load  30  (also shown in phantom). Those of skill in the art will appreciate that lift apparatus  10  enables lift and placement of the load by manual pivotal manipulation of boom member  22 .  
         [0017]     Base  12  further includes a generally triangular, hinged, pivotal brace mechanism  32  that includes three brace members  34 ,  36 ,  38 ; a snapper pin  40  for fixing it in place between support legs  14 ,  16 ,  18  and a generally square fulcrum base plate  42 . Those of skill in the art will appreciate that support legs  14 ,  16 ,  18  are welded or otherwise durably and fixedly mounted to a lower surface of a tripod cap  42 . At the base of each of support legs  14 ,  16 ,  18  is a generally square pad such as pad  44  for mounting a wheel, as will be described below by reference to  FIGS. 6 and 7 .  
         [0018]     Fulcrum, or pivot/support, mechanism  20  will be described below in more detail by reference to detail A of  FIG. 1 . From  FIG. 1 , however, it may be seen to include a frame  46  defining a vertical rectangular channel  48  through which boom member  22  extends horizontally for pivotal mounting at a desired height within the channel. Those of skill in the art will appreciate that height adjustment and pivotal mounting of boom member  22  in fulcrum mechanism  20  is made possible by providing a vertical array of opposing through-hole pairs formed in the upright sidewalls of frame  46  as shown. Fulcrum mechanism  20  is fixedly and durably mounted atop tripod cap  42  as by seam or spot welding (the former being most preferred) or other suitable technique.  
         [0019]     In accordance with one embodiment of the invention, boom member  22  includes three separate sections or components: A lift member  50  and a counterbalance member  52  receive in proximal ends thereof a pivot member  54 , with each of the lift member  50  and counterbalance member  52  pinned to pivot member  54  through corresponding receiving holes and with pivot member  54  pinned at a desired height within frame  46 . As will be better seen by reference below to Detail A, three hitch pins  56  are used to pin counterbalance member  50  to pivot member  54 , lift member  52  to pivot member  54  and pivot member  54  to pivot frame  46 . A load attachment mechanism  58  for securing load  30  is provided at a distal end of lift member  50 , and a counterweight support member  25  is provided at a distal end of counterbalance member  52  for carrying one or more counterweights  26   a,    26   b,    26   c,    26   d,    26   e,    26   f.  (Those of skill in the art will appreciate that, in accordance with one embodiment of the invention, counterweight support member  25  weighs approximately 30 pounds, thus effectively causing rearward counterbalance member  52  of boom  22  to pivot downwardly toward the support surface, e.g. a roof, when the boom is charged with neither load nor counterweight.)  
         [0020]     Invented apparatus  10  in use is operated manually to lift and maneuver load  30  as desired by manually manipulating counterbalance member  52 . Those of skill in the art will appreciate that a mechanical advantage of approximately 2:1 is obtained by a 2:1 length ratio between counterbalance member  52  and lift member  50 . Moreover, load  30  is effectively counterbalanced by one or more counterweights  26   a,    26   b,    26   c,    26   d,    26   e,    26   f  to facilitate maneuvering the load into proper position and orientation. More or fewer counterweights  26   a,    26   b,    26   c,    26   d,    26   e,    26   f  can be used to roughly adjust the counterbalancing effect on variable loads. Also, by virtue of the novel construction of the counterweights themselves, very fine adjustment of counterbalancing effect is possible.  
         [0021]     This is because, in accordance with one embodiment of the invention, the counterweights are ballast-filled containers to and from which ballast can be added or subtracted. Preferably, the counterweights are made of water-fillable, sealed containers that can be simply filled in situ (at the site where the apparatus is to be employed in lifting and positioning a load) and slid onto either side of counterweight support member  25 , as shown in  FIG. 1 . Thus, in accordance with one embodiment of the invention, infinite adjustment of counterbalance effect can be achieved for delicate load handling tasks. Moreover, the lightweight portability of invented apparatus  10  is not compromised by the fixed weight of an integral counterweight. Instead, the containers can remain empty (and thus as light as air) while the boom lift apparatus is positioned at the installation site, e.g. on top of a roof, and then ballast, preferably liquid and most preferably water, can be introduced into the containers to a desired fill factor and corresponding weight.  
         [0022]     Those of skill in the art will appreciate that six 6-gallon containers when filled with water (weighing approximately 8.3 pounds/gallon) would weigh approximately 300 pounds, which when added to the 30-pound weight of counterweight support arm  25  would provide adequate counterweight to an approximately 660 pound load. This is because of the 2:1 leverage obtained by use of the invented boom lift having a longer counterbalance arm and a shorter load lift arm, as described and illustrated herein. Importantly, smaller or larger loads are accommodated as well, by simply reducing or increasing the mass of the counterweights that are secured to counterweight support member  25  (the length of which may, within the spirit and scope of the invention, be decreased or increased to accommodate fewer or more containers). Those of skill in the art also will appreciate that alternative counterweight numbers and configurations are within the spirit and scope of the invention.  
         [0023]     After use, the water or other ballast can be dumped or siphoned from the containers and the boom lift apparatus easily transported to the next work, e.g. HVAC/R installation, site.  
         [0024]     Those of skill in the art will appreciate that the purpose of hinged brace  32  is to permit triangular brace members  34 ,  36 ,  38  to be moved out of the way for easy transport of invented apparatus  10 . Those of skill will also appreciate that construction of boom mechanism  22  in sections similarly facilitates break down and reduces over dimension of invented apparatus  10  during transportation. Finally, those of skill in the art will appreciate that, in accordance with one embodiment of the invention, the bases of support legs  14 ,  16 ,  18  are equipped with wheels (not shown in  FIG. 1 ) to facilitate positioning of invented apparatus  10  while it is in use, i.e. while a load is being positioned and oriented for installation. Thus, tripod base  12  of invented apparatus  10  provides a relatively wide and deep stance or footprint to stabilize loads while also facilitating smooth and effective load movement from one place to another. The wheels, which can be employed in any of the three embodiments described and illustrated herein, will be described in more detail below by reference to  FIGS. 6 and 7 .  
         [0025]     Detail A illustrates in fragmentary detail isometric view fulcrum mechanism  20 , load member  50  and lift member  52  as they are assembled in accordance with one embodiment of the invention. Fulcrum mechanism  20  will be understood to include frame  46  defining channel  48 , as described above. Frame  46  may be seen to include a fulcrum base plate  60 , left and right sidewalls  62 ,  64 , left and right gusset pairs  66   a,    66   b,    68   a,    68   b  and fulcrum cap  70 . Left and right sidewalls  62 ,  64  are formed of opposing U-shaped angle members having their U-shaped openings facing outwardly, away from one another, as shown. Sidewalls  62 ,  64  have formed therein four sets of opposed through hole pairs  72 ,  74 ,  76 ,  78  spaced apart by approximately 4″ and preferably evenly spaced along vertically extending sidewalls  62 ,  64  to permit height adjustment of boom mechanism  22  by selectively pinning pivot member  54  at a desired elevation within channel  48  by a hitch pin  56 .  
         [0026]     Those of skill in the art will appreciate that proximal ends of load member  50  and lift member  52  extend slidably around pivot member  54  on either end of pivot member  56  and are pinned in place with a pair of hitch pins  56 . In accordance with one embodiment of the invention, there is a 4″ gap between the proximal ends of load member  50  and lift member  52 , so that pivot member  54  alone extends through channel  48  and so that load member  50  and lift member  52  extend respectively fore and aft of the channel. Preferably, hitch pins  56  are cotter key locked in place after they are installed, thereby to secure the affected assemblies. The same is true of snapper pin  40  in tripod base  12  (refer briefly back to  FIG. 1 ). (Most preferably, each cotter key corresponding to a hitch pin or snapper pin is physically affixed to its respective pin, as is known, to prevent key loss.) It will be understood by those of skill in the art that more or fewer hole pairs may be provided, within the spirit and scope of the invention, having a greater or lesser gap therebetween. It will also be understood that the component parts of frame  46  preferably are welded, e.g. seam-welded (most preferably) or spot-welded. But those of skill in the art will appreciate that, within the spirit and scope of the invention, frame  46  may assume alternative forms made by alternative means, such as any suitably durable structure formed alternatively by one or more of extruding, machining or casting.  
         [0027]     Any suitable materials and dimensions can be used in invented apparatus  10 , and the following description of materials and dimensions used in accordance with one embodiment of the invention is intended to illustrate but not to limit the scope of the invention. For example, boom load and lift members  50 ,  52  preferably are of 2.5″ square aluminum (hollow) tubing having 0.25″ (¼″) thick walls, with load member  50  being approximately 5′ long and with lift member  52  being approximately 10′ long. Pivot member  54  preferably is of 2″ square milled steel tubing having ¼″ thick walls, with pivot member  54  being approximately 18-24″ long. Support legs  14 ,  16 ,  18  preferably are of 2″ square aluminum tubing (radius corner) having ¼″ thick walls, with legs  14 ,  16  being approximately 5′ long and with leg  18  being approximately 82″ long. (Those of skill in the art will appreciate that preferably the triangular base of the tripod that supports the fulcrum is nominally vertically aligned with the lateral center of mass of apparatus  10 , there by to obtain maximum horizontal stability of invented apparatus  10 .) Tripod cap  42  preferably is of 10″ square flat aluminum having a thickness of ¼″. Brace members  34 ,  36 ,  38  preferably are 1″×1″ aluminum angle brackets having a thickness of ¼″, with members  36 ,  38  being approximately 38″ long and with member  34  being approximately 15.5″ long.  
         [0028]     Fulcrum base plate  60  is of 10″ square flat steel having a thickness of ¼″. Vertical sidewalls  62 ,  64  and gussets pairs  66   a,    66   b,    68   a,    68   b  are also of flat steel having a thickness of ¼″. Fulcrum cap  70  is of 5″ square flat steel having a thickness of ¼″. Those of skill in the art will appreciate that, in accordance with one embodiment of the invention, the component parts of fulcrum mechanism  20  are milled or otherwise formed steel, thus providing greater durability but slightly higher weight, whereas the remaining components of invented apparatus  10  in large part are formed of aluminum, providing adequate durability and lower weight. Nevertheless, it is contemplated as being within the spirit and scope of the invention that one or more suitable alternative materials for these component parts of the invented apparatus are within the spirit and scope of the invention.  
         [0029]     In accordance with one embodiment of the invention, support leg base plates  44  are of 5″ square flat aluminum having a thickness of ¼″. Load member  25  is a 1″ round Schedule  40  ends-threaded pipe and includes screw-on end caps. Hitch pins  56  are of an aluminum alloy 0.5″ in diameter and 4.75″ in length. Finally, snapper pin  40  is of an aluminum alloy 0.3125″ ( 5/16″) in diameter and 3.5″ in length. As described above, preferably the hitch pins and the snapper pins are integrally (inseparably) equipped with secure, cotter-type key locks.  
         [0030]      FIGS. 2 and 3  illustrate the first embodiment of the invention corresponding with  FIG. 1 , respectively in a front and side elevation. Briefly,  FIGS. 2 and 3  respectively in front and side elevation show tripod support base  12  including front support legs  14 ,  16  (omitted from  FIG. 2 , for the sake of clarity, is rear support leg  18 ); counterweight arm  24  including elongate counterweight member  52 ; front brace member  34 ; fulcrum mechanism  20  including elongate pivot member  54 ; boom mechanism  22 ; lift mechanism  22 ; load attachment mechanism  58 ; and load arm  28  including elongate load member  50 .  
         [0031]     In accordance with the first embodiment of the invention described and illustrated herein, a load of up to approximately 500-1000 pounds readily can be lifted, positioned, oriented and placed. Moreover, such can be accomplished with only one or two operators, since the load is counterbalanced and leverage is increased in accordance with the invention. This capacity may, within the spirit and scope of the invention, be increased or decreased by dimensional scaling. It is contemplated as being within the spirit and scope of the invention to reinforce counterbalance member  52  (and/or lift member  50 ) along its substantial length by seam or spot welding (or otherwise affixing) a length of 1″×1″ aluminum angle having a thickness of ¼″ thereto. Such reinforcement, if deemed necessary or desirable, can be added to any of the embodiments of the invention as described and illustrated herein, and is within the spirit and scope of the invention.  
         [0032]      FIG. 4  illustrates in isometric view the invented apparatus  10 ′ in accordance with a second embodiment of the invention. Very briefly, it will be understood that this second embodiment of the invention features a boom lift assembly that is separable from the tripod base for ease of passage through small openings. Other structural and material aspects of the second embodiment are identical with those of the first embodiment and, for the sake of brevity, will not be described in detail.  
         [0033]      FIG. 4  illustrates an alternative embodiment of the invention at  10 ′. All particulars of invented apparatus  10 ′ are identical to those of invented device  10  described above, except that a detachable tripod cap  42 ′ is provided atop modified support legs  14 ′,  16 ′,  18 ′ and except that a triangular brace mechanism  32 ′ is removably pinned to support legs  14 ′,  16 ′,  18 . Those of skill in the art will appreciate that this alternative configuration achieves even better portability of invented apparatus  10 ′, while retaining ease of assembly on site. Access through smaller openings can be obtained using invented apparatus  10 ′ since all three support legs and the brace itself are easily removed during transportation and easily assembled for use.  
         [0034]     Tripod cap  42 ′ is equipped with square tubular extensions  80 ,  82 ,  84  onto which support legs  14 ′,  16 ,  18 ′ readily slide and are secured by the use of three cotter key-like locking hitch pins  56  (only one of which is shown, for the sake of clarity). Those of skill in the art will appreciate that tubular extensions  80 ,  82 ,  84  and support legs  14 ′,  16 ′,  18 ′ are equipped with corresponding through holes (also not shown, for the sake of clarity) for pinning purposes. Brace mechanism  32 ′ includes fixed brace member  34 ′ having through holes (also not shown) formed therein and removable brace members  36 ′,  38 ′ also having through holes formed therein on either end thereof to receive three corresponding snapper pins  40  for quick and easy assembly and employment of invented apparatus  10 ′ on site. Thus it will be appreciated by those of skill in the art that triangularly configured support legs  14 ′,  16 ′ fixed by brace member  34 ′ can readily be fitted through a smaller opening with third support leg  18 ′ and corresponding brace members  36 ′,  38 ′ and tripod cap  42 ′ removed. Thus the ‘transport footprint’ of invented apparatus  10 ′ is reduced to facilitate transportation without significant negative impact on ease of assembly on site.  
         [0035]      FIG. 5  illustrates in isometric view the invented apparatus  10 ″ in accordance with a third embodiment of the invention. Very briefly, it will be understood that this third embodiment of the invention features an optional outrigger mechanism associated with the base and optional cable truss and crank lift mechanisms associated with the boom. Other structural and material aspects of the third embodiment are identical with those of the first and second embodiment and, for the sake of brevity, will not be described in detail.  
         [0036]     Apparatus  10 ″ includes an outrigger mechanism indicated generally at  86 , the outrigger mechanism including two laterally opposed outrigger legs  88 ,  90  that, while selectively widen the footprint and thus increase the stability of the boom lift. Those of skill in the art will appreciate that support legs  14 ″ and  16 ″ are equipped in accordance with this embodiment of the invention with mounting brackets  92 ,  94  that pivotally mount outrigger legs  88 ,  90  so that when employed the outrigger legs extend outwardly but generally within the plane formed by support legs  14 ″,  16 ″, as shown. Those of skill will appreciate that pivotable outrigger legs  88 ,  90  permit tripod base  12 ″ to be easily transported with a reduced footprint by pivoting the outrigger legs into generally axial alignment with their corresponding support legs. Those of skill also will appreciate that, within the spirit and scope of the invention, the outrigger legs can be removably, rather than fixedly, attached to the mounting brackets, as by pivotally pinning with a pair of hitch pins. Finally, those of skill in the art will appreciate that outrigger legs  88 ,  90  and mounting brackets  92 ,  94  preferably are made of any suitably durable material, e.g. ¼″ tubular and/or angular aluminum.  
         [0037]     Those of skill will appreciate that, not shown in  FIG. 5 , for the sake of clarity, are wheels on pads  44  provided on the bases of support legs  14 ″,  16 ″ and outrigger legs  88 ,  90 . Those of skill also will appreciate that  FIG. 5  shows fixedly mounted tripod cap  42  rather than detachably mounted tripod cap  42 ′, although within the spirit and scope of the invention either can be employed with invented apparatus  10 ″. Apparatus  10 ″ also includes a square tubular steel member  96  atop fulcrum mechanism  20 , member  96  extending upwardly from and mounted on fulcrum cap  70 . Member  96  includes a cable eyelet  98  at its upper reach to accommodate a cable  100  extending therethrough. Cable  100  under predetermined tension extends through eyelet  98 , with a fore end thereof pinned to load lift member  50 ′ and with an aft end thereof pinned to counterbalance member  52 ′, as shown. Those of skill in the art will appreciate that member  96 , cable  100 , load lift member  50 ′ and counterbalance member  52 ′ thus form a cable bow truss to stabilize and support the ends of beam member  22  and to provide added lift capability of invented apparatus  10 ″.  
         [0038]     A forward end of a second cable  102  is provided with a load hook  104  and a rearward end of cable  102  is wound around a spindle (not visible in  FIG. 5 ) that forms part of a crank mechanism  106  having a manual crank handle  108 . The substantial length of cable  102  will be understood to extend through counterbalance, pivot and load lift arms  52 ′,  54 ′ and  50 ′, and to exit load lift arm  50 ′ near its distal end through a guide mechanism, e.g. an eyelet,  110 . Those of skill in the art will appreciate that the hook  104  end of cable  203  can be alternately spooled out and in to reach and secure a load (not shown in  FIG. 5 ). In other words, the nominal elevation of hook  104  can be adjusted relative to the distal end of load lift member  50 ′ by manually operating crank mechanism  106  by turning crank handle  108 , thereby facilitating a load&#39;s secure attachment.  
         [0039]      FIGS. 6 and 7  illustrate the third embodiment of the invention shown in  FIG. 5  in a front and side elevation, respectively, and also show the wheels that, within the spirit and scope of the invention in all of its illustrated embodiments, preferably are included for the purpose of mobility. It can be seen from  FIG. 6  that preferably all support and outrigger legs, whether three or five in number (only four of which are shown in  FIG. 6  for the sake of clarity, with the fifth wheel being shown only in  FIG. 7 ), are equipped with wheel mechanisms (designated  112 ,  114 ,  116 ,  118 ,  120  in  FIGS. 6 and 7 ). The lateral distance between each lateral wheel mechanism and its corresponding outrigger wheel mechanism is preferably approximately 30″. In accordance with the wheeled embodiment(s) of the invention, the wheel mechanisms are seam or spot welded or otherwise affixed to pads  44  so that their pneumatic tires freely turn.  
         [0040]     Those of skill in the art will appreciate from  FIG. 7  that invented apparatus  10 ,  10 ′,  10 ″ in any of its various embodiments, of which the embodiment in  FIG. 7  is typical, provides a boom lift that is pivotal, as indicated by curved arrows. It will also be appreciated that the invented apparatus also provides for wheeled movement that is fore and aft, as indicated by straight arrows. These two movements facilitate on site (in situ) securement, lift, positioning, orientation and placement of a substantial load.  
         [0041]      FIG. 8  is a flowchart that illustrates the invented boom lift method in accordance with another embodiment of the invention. The boom lift method will be understood to include a) transporting to a work site separate components including a tripod having a fulcrum at its apex and wheels at its base, a boom having a counterbalance arm and a load lift arm, one or more counterweights and one or more pins (block  800 ); assembling the separate components at the work site using the one or more pins to join the components into an assembled boom lift, said assembling including pivotally mounting the boom member on the fulcrum of the tripod (block  802 ); securing a load on a load lift end of the boom at the work site (block  804 ); securing the one or more counterweights on a counterbalance arm of the boom member at the work site (block  806 ); and manually maneuvering the counterbalance arm while wheeling the boom lift to position the load at the work site (block  808 ). Those of skill in the art will appreciate that alternative methods of using the invented boom lift apparatus are contemplated and are within the spirit and scope of the invention.  
         [0042]     In brief summary, the advantages of the invention are many. The invention provides a simple but elegant solution to roof-top or other hard-to-reach work sites where installations of modestly heavy loads is required. It does so by configuring a boom lift in discrete, lightweight component parts that are readily transported to the work site even through narrow openings such as windows, doorways, stairways, etc. due of their narrow span when so broken down. Yet the boom lift assembles quickly using easily hitched pins to join the component parts on site into a durable boom lift configuration. Importantly, the boom lift provides mechanical advantage of leverage by the disparate lengths of its load lift arm and counterbalance arm. Also importantly, the counterbalance arm is counterweighted on site by the simple provision of a preferably ubiquitous liquid ballast such as water easily introduced into one or more sealable containers. The boom lift is just as easily disassembled, therefore, after use.  
         [0043]     Accordingly, while the present invention has been shown and described with reference to the foregoing embodiments of the invented apparatus and method, it will be apparent to those skilled in the art that other changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.