Abstract:
Apparatus for lifting objects into preformed openings in buildings. These openings can be recessed. The apparatus has a frame which has a head section and a tail section. The head section and tail section are rotably mounted to each other. A backstand is provided which is attached to the head section for preventing the objects to be lifted from moving as the objects are transported. Supports or forks are also provided which protrude from the head section and are used to support the objects to the transported. The apparatus has a leveling system which includes movable counterweights attached to chains. The movable counterweights balance the effect of the objects that the apparatus supports, keeping it level in the horizontal direction. The backstand can be folded down into the head section and the tail section folded onto the head section. Prior to or after use, as the apparatus is a lightweight, compact system, it can be transported in a pickup truck.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     The invention relates in general to apparatus for lifting objects into a structure and, more particularly, to a folding, lightweight apparatus that easily can assist in lifting panels or the like into preformed openings of a building under construction. 
     II. Description of the Prior Art 
     Modern tall office buildings are generally constructed as a shell with openings for panels and windows or the like. Buildings of this type can reach heights of 70 stories. The shell of the building is constructed with openings. Precast or prefabricated panels are then placed within these openings. These construction panels are of various sizes, shapes and thicknesses. Precast panels are made of reinforced concrete and may have heights as tall as 10 feet and lengths to 20 feet. These thicknesses may vary from 3 to 12 inches. Reinforced concrete panels with dimensions of this order are extremely heavy. Maneuvering of such heavy reinforced concrete panels is therefore difficult. The openings for receiving such a concrete panel may be at or above the 10th story making it necessary to lift panels to the 10th story or higher, and place them within the openings. Ordinarily, cranes are used to lift the panel up to the openings. The cranes may be situated on the ground or as the number of stories of the building increases, it is necessary to position the crane on the top floor of the building as it is being constructed or use a tower crane. A further complication arises in the construction of modern concrete steel buildings in that spandral beams are required. These spandral beams are so constructed that the openings for precast concrete panel may be as much as 3 feet inside the face of the spandral beam. The spandral beam therefore functions as a hindrance to the insertion of the precast concrete panel into the opening of the building. Without going into unnecessary detail, it is well known that the spandrals are required. The spandrals are required to be in place before the precast concrete panels are fit into the opening. Normally, the method of installing a panel of this type in the recessed opening in the building would be to attach lifting rings to the top of the panel. The rings would be attached with suitable bolts and a crane would be hooked to the lifting ring to lift the precast panel to the desired height in the building. Once the panel is lifted in close proximity to the opening it is to be fit into, construction workers will begin attempting to grab the panel and pull the panel into the opening. It is to be appreciated that the panel is large and heavy and the workers must manually pull the panel into the opening. After the panel has been pulled into the opening, it must be secured in place within the opening. The panel may be secured in place by bolting the panel to the structure in the building, welding the panel to the building, or by other suitable means. This procedure has obvious shortcomings. These shortcomings include the amount of time that workers take to fit one panel in place, and also due to the awkwardness of grabbing and fitting the panel in the opening, the possibility of an accident involving the workers. 
     U.S. Pat. No. 4,671,721 issued to applicants on Jun. 9, 1987, addressed the problems previously outlined above. In this embodiment, an apparatus and method for positioning an object in a building was disclosed. This invention showed that precast panels can be delivered to openings in office buildings in a controlled manner which facilitated placing the panels in the building. The invention had many advantages over the prior art. On the other hand, the invention had a shortcoming in that the apparatus used to lift the panels was of itself extremely bulky and heavy. Although this shortcoming did not necessarily affect the performance of what can be described as &#34;the flying forklift,&#34; it did affect its use in construction sites as transportation of the apparatus to and from various sites became a major drawback. Put simply, it would be desirable to have an apparatus that can be transported by a pickup truck as opposed to other more costly methods, and still make installation of precast panels or the like in openings in a building easier and safer than had been in the prior art. Applicants have therefore come up with a new apparatus which fulfills all the desired requirements, as shown in U.S. Pat. No. 4,671,721 and has further advantages in its use and transportation as will become clear from the specification herein. 
     SUMMARY OF THE INVENTION 
     This invention describes an apparatus for lifting loads such as precast concrete panels into openings in a structure under construction. The invention can be used by a lifting device such as a crane and would be located between the load line of the lifting device and the panel to be elevated. The apparatus is constructed such that the objects lifted can be offset at various distances with respect to the load line of the lifting device and therefore can be positioned within recessed openings of the structure in a controlled and safe manner. The apparatus has a frame which has two sections: a head section and a tail section. The tail section is mounted to the head section in such a manner that the head section can be folded over the tail section prior to the use of the apparatus. In practice, the head section and the tail section would be of approximately equal lengths. The head section, however, would be wider than the tail section. The head section also includes a backstand attached thereto. The backstand is used as a support for the objects being lifted to prevent those objects from moving forward on the apparatus. The backstand has a substantially vertical member which can be called a first vertical member and a second support member attached at one end to the top of the vertical member and at the other end to the head section itself. Outwardly directed supports are provided which protrude outwardly from the head section. Supports or forks are secured to the head section and are for receiving and supporting the objects to be lifted. The apparatus also includes a leveling system mounted on the frame for leveling the frame horizontally when the forks receive objects to be lifted. The leveling system includes a movable counterweight attached by chains to a motor which is used to keep the frame level as objects are transported. It also should be noted that the vertical and support members of the backstand can be disconnected from each other and folded down over the head section. The supports for the objects to be carried or forks, as they are called, can be disconnected from the head section when not in use and secured thereto for transportation, thus minimizing the dimensions of the entire apparatus package when it is not in use. Preferably, the entire apparatus can be made of a lightweight structural material such as aluminum, and in fact is in practice lighter than the objects that will be transported by the apparatus. Besides the advantages of the apparatus in positioning objects inside recessed openings in a structure, it further has the desirable feature of being compact and lightweight. These qualities allow easy and rapid transportation of the apparatus which is highly desirable for its use on construction sites and allows use of this apparatus with substantially lighter capacity lifting devices. When the apparatus is transported, its dimensions have been minimized to further this end of rapid and easy transportation. This makes the apparatus desirable from an economic and functional point of view over the apparatus described in U.S. Pat. No. 4,671,721. These and other objects and advantages of the present invention will become more apparent from the following detailed description when taken into conjunction with the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is an isometric drawing showing the apparatus of the present invention. 
     FIG. 2 is a plan view of the apparatus of the present invention. 
     FIG. 3 is a side elevation view of the apparatus of the present invention. 
     FIG. 4 is a side elevation of the apparatus in the fold position. 
     FIG. 5 is an isometric schematic showing counterweight and drive system of the apparatus. 
     FIG. 6 is a side elevation view of the apparatus of the present invention featuring a sliding flange as part of the leveling system. 
     FIG. 7 is a fragmentary side elevation view illustrating the connection of the forks to the frame of the apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1, 2 and 3, the invention can be described. A forklift, generally designated as 10, is shown having a frame 12. Frame 12 has a head section 14 and a tail section 16. Head section 14 and tail section 16 are approximately equal in horizontal length. Head section 14 has a forward portion 18 of similar dimensions in width to the tail section 16. Head section 14 also has a rear portion 20 which is wider than tail section 16 and the forward portion 18 of head section 14, as best shown in FIG. 1. Head section 14 has a pair of head support beams 22a and 22b which run the length of head section 14 and are parallel to each other. Head support beams 22a and 22b are connected through connecting flanges 24a and 24b to tail support beams 26a and 26b, respectively. The tail support beams 26a and 26b are pivotally mounted to head support beams 24a and 24b, respectively, through a set of pins generally designated as 28. As will be described later, prior to or after use of forklift 10, the tail section 16 can be folded over the head section 14 by removal of suitable pins 28. 
     The rear portion 20 of head section 14 has a set of cross supports 30a,b and 32a,b. Rear portion 20 of head section 14 also has length supports 34a and 34b which connect cross supports 30a and 32a, and 30b and 32b, respectively, at one end and length supports 34c and 34d which connect cross supports 30a and 32a, and 30b and 32b, respectively, at the other end. Diagonal head section supports 36a and 36b connect one end of cross supports 30b and 32b to head support beam 22a. Correspondingly, diagonal head section supports 38a and 38b connect the other end of cross supports 30b and 32b, respectively, to head support beam 22b. To further stabilize the head support beams 22a and 22b, a lateral beam support 40 is connected between the head support beams 22a and 22b. Tail section 16 has a cross bracing system which includes tail cross beams 42a, 44a, and 46a, which connect to tail support beams 26a and 26b on the top of these beams. In a like manner, tail cross beams 42b, 44b and 46b connect to tail support beam 26a and 26b on the bottom of these beams. A pair of diagonal tail cross beams 48a and 50a are also used, connecting at one end to the top of tail support beam 26a and at the other end to the top of tail support beam 26b. A second pair of diagonal tail cross beams 48b and 50b connect at the bottom of tail support beams 26 a and 26b as shown best in FIG. 1. 
     The forward portion 18 of head section 14 has a backstand generally designated as 52 attached thereto. Backstand 52 has a pair of vertical legs 54a and 54b and backstand diagonal supports 58a and 58b which connect backstand legs 54a and 54b to the top of head support beams 22a and 22b, respectively. The vertical legs 54a and 54b of backstand 52 connect to a front cross support beam 60 which is mounted partially below the head support beams 22a and 22b. Diagonal cross braces 62a and 62b connect between front cross support beam 60 and cross support 30a. As best shown in FIGS. 2 and 3, a pair of forks 64a and 64b fit under front cross support beam 60 and extend rearward contacting the underside of cross support 30b. A pair of vertical uprights 66a and 66b connect cross supports 30a and 30b of head section 14. It also should be noted that a second pair of vertical uprights 68a and 68b connect cross supports 32a and 32b at each of their ends. 
     The forklift 10 can be grasped by a conventional lifting device (not shown) having a load line 65 and hook 67 (FIG. 6). Cables 69a,b,c,d would run from the hook 67 to four &#34;pick&#34; points 70a,b,c, and d, (FIG. 2) which are prelocated holes in flanges located in the head support beam 22a and 22b. The center line of the load line 65 is directly over cross support 30a and positioned at the midpoint of its length. 
     Referring now to FIG. 5, the counterweight and drive system of the apparatus can be described. FIG. 5 shows a leveling system generally designated as 71 with the apparatus. It can be appreciated that as a load is received upon the forks 64a and 64b, the apparatus would tip toward the end bearing the load. To correct this problem, a counterweight 72 is provided with plastic gibbs (not shown). The plastic gibbs are mounted on the underside of the counterweight 72. Counterweight 72 is a rectangular slab composed of a suitable material such as aluminum. The counterweight 72 is moved back and forth within the tail support beams 26a and 26b by an electric motor 74 and suitable transmission means subsequently described. The motor 74 is mounted on the part of the frame 12 which overhangs head support beams 22a and 22b. The motor 74 is therefore supported by diagonal head section supports 38a and 38b. A generator 76 is connected to the electric motor to provide an electrical input thereto through a switch box 78. The generator 76 preferably is mounted to frame 12, being supported by diagonal head section supports 36a and 36b. Motor 74 can be activated by a remote switch 80 running from switch box 78. The output shaft of motor 74 is connected to a sprocket 84 which drives a second sprocket 86 through a chain 88. Sprocket 86 is connected to a shaft 90 which is also connected to and drives sprocket 92 and sprocket 94. The shaft 90 is suitably supported by bearings in the head section support beams 22a and 22b so as to allow support and rotation of that shaft. A second chain 96 is used to connect sprocket 92 and sprocket 98. A third chain 100 is used to connect sprocket 94 mounted on shaft 90 to sprocket 102. Sprockets 98 and 102 are suitably mounted to tail support beams 26b and 26a, respectively. Each end of chain 100 and chain 96 is connected to the counterweight 72. The net result of this system is that if the output shaft of motor 74 is caused to rotate one way by use of the remote switch 80, the counterweight 72 will be forced rearward within the tail section 16. Use of remote switch 80 causing the output shaft of the motor 74 to rotate in the opposite direction will result in the counterweight to move forward within the tail section 16. The remote switch therefore can cause the counterweight to move and thereby level the apparatus once a load has been received on the-forks 64a and 64b. The heavier the load, the farther rearward the counterweight 72 will be required to be driven. Once the apparatus is levelled, the remote switch 80 can be placed within the frame 12 and the apparatus and load moved to the desired location into a structure by the lifting device. 
     Referring to FIG. 6, a preferred feature of the apparatus can be described. Initially, it must be kept in mind that the apparatus for lifting objects into structures herein described has as one of its objects to be as lightweight and compact as possible while able to transmit a load of a given weight. In other words, a high priority in reducing overall length and weight of the apparatus exists. 
     FIG. 6 illustrates a feature of the invention for improving levelling adjustability for receiving objects. FIG. 6 shows a beam 104 mounted lengthwise between cross support 30b of head section 14 and front cross support beam 60. Mounted on this beam 104 is a sliding flange 106. Sliding flange 106 is mounted with plastic bearings on a rail (not shown) which is placed over beam 104 and allows flange 106 to slide fore and aft relative to the apparatus. Sliding flange 106 has an eyehole 108 which receives the rear cables 69a and 69b of the apparatus. The two rear cables 69a and 69d from the apparatus are fed through a pair of pulleys 110a and 110b located at &#34;pick points&#34; 70a and 70d before being fastened to eyehole 108 of sliding flange 106. The front cables 69b and 6c are held by the lifting device and attach to pick points 70b and 70c. A lip 112 is located on the underside of sliding flange 106 which can be contacted by the fore end of the counterweight 72 when the counterwieght 72 is moved to a position closest to the head of this apparatus. The counterweight 72, therefore, can cause the sliding flange 106 to move toward the head of the apparatus. The sliding flange would draw the rear cables 69a and 69d with it, effectively shifting the center of gravity of the apparatus forward with-respect to the crane. The length of cable from the pulleys 110a and 110b to the eyehole 108 of the sliding flange 106 would obviously be increased at the reduction of the length of cable from the hook 67 of the lifting device to pulleys 110a and 110b causing the above mentioned shift in center of gravity. In the no load situation, therefore, the apparatus can be held level without sacrificing additional length, weight or load capacity. Once the forks 64a and 64b receive a load, the counterweight 72 can be caused to move rearward as previously described to balance that load. The length of cable between the pulleys 110a, 110b and the eyehole 108 of the sliding flange 106 thereby decreases until a preset stop 114 is reached. The apparatus would then be operated as previously described herein. 
     FIG. 7 shows a detail of the forks 64a and 64b used with the present apparatus. It should be noted that conventional cantilevered forks if used with the present invention would present problems. The forks used in conjunction with the present invention preferably should be functional, i.e., capable of supporting the loads carried by the apparatus, yet detachable so as to reduce the overall size of the apparatus during transportation. To accomplish these objects, the cross support beam 60 has a channel 116 which is adapted to receive a flange 118 located in the mid-portion of forks 64a and 64b. The flange 118 of each fork interlocks with the channel 116 of the cross support beam 60. To further bear the load on the forks 64a and 64b, the rear-most end of the forks fits under cross support 30b thereby bracing the forks and distributing the load thereon in a workable manner. In practice, the flanges 118 of forks 64a and 64b could be fastened with bolts 120 or detachably pinned to the channel 116. Removal of the forks 64a and 64b after use of the apparatus would require only the withdrawing of bolts 120 or suitable pins (not shown) through the flanges 118 and channel 116. It also should be noted that the sideways distance between the forks can be adjusted in an obvious manner to accommodate a variety of loads. 
     After operation of the apparatus, the entire apparatus can be completely folded for storage or transportation purposes. To do this, initially the forks 64a and 64b would be removed as described immediately above. The forks 64a and 64b could be temporarily attached to head support beams 22a and 22b by flanges appropriately located on those beams (not shown). The backstand 52 can be folded in a manner best shown in FIG. 3. The rearmost end of the backstand supports 58a, b relative to the apparatus can be detached from head support beams 22a and 22b by removal of suitable pins. Backstand diagonal supports 58a and 58b are rotably connected to backstand legs 54a and 54b, respectively. When the suitable pins are removed, the supports 58a, b can be slid along the top of the head support beam 22a and 22b causing the entire backstand 52 to lie flat on top of support beams 22a and 22b. With the forks 64a, b tucked away and the backstand flat, tail section 16 can be folded over head section 14. To accomplish this folding, the bottom pins 28 are removed and the tail section 16 rotated in a manner illustrated in FIG. 3 allowing the tail section 16 to lie on top of the head section 14. The apparatus can thereby be conveniently stored or transported. 
     The invention may be embodied in other forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foreging description, and all change which comes within the meaning and range of equivalency of claims are intended to be embraced therein.