Driving attachment for eye-bolt hangers and the like
BACKGROUND 
     1. Field of the Invention 
     This invention relates to a portable drill attachment, specifically all attachment which can be used to drive eye-bolts, J-bolts, screw hooks, and other hanger-type devices which cannot be &#34;chucked&#34; because of their physical configuration. 
     2. Discussion of Prior Art 
     Eye bolts with lag threads are commonly used to hang loads from overhead locations such as beams and ceilings as well as walls, trees and other structures. po In the usual procedure, the worker will either hammer the eye-bolt into the material (typically wood) to grab a few threads, or he will pre-drill a pilot hole; in either case the threaded shank is thereafter manually screwed into the material using pliers or some other leverage effecting device. The procedure is both cumbersome and time consuming--and generally requires several different tools. Moreover, unless a pilot hole is drilled, the starting process can be frustrating and difficult since hammering is likely to deform the end (in the case of eye-bolts, the eye is deformed whereas off axis hangers such as J-bolts and square bent hooks are difficult to hammer and more likely therefore to become damaged or distorted). 
     The desirability of a device which is sufficiently universal to accommodate a wide range of hanger types and sizes so as to facilitate their rapid installation will be readily appreciated. Accordingly, it is a primary object of the invention to provide a driving attachment for a portable drill which can be used efficaciously for a wide range of hanger types and sizes, including but not limited to: 
     (a) shank diameters ranging from 1/16&#34; to 7/16&#34; 
     (b) head dimensions ranging from 1/8&#34; to 11/4&#34; 
     (c) head configurations including round, L, J, offset round, square, and combinations thereof. 
     It will be understood that to accomplish these objectives with a single device, the invention must effectively meet and resolve numerous difficulties, thus 
     (a) for different shank diameters, 
     1) the torque must be axially centered by the gripping elements and, 
     2) the shank neck must be mechanically restrained so as to maintain the thrust axis alignment. 
     (b) for different head dimensions, the point of application of the axial force must be centered with the torque axis. 
     (c) for different head configurations, the point of application of the axial force must line up with the torque axis. 
     OBJECTS AND ADVANTAGES 
     Accordingly, other objects and advantages of the invention are: 
     (a) to provide an attachment for installing eye-bolts, J-bolts, screw hooks, and the like, using a manual or power drill. 
     (b) to provide a driver that eliminates the need to hammer a starting indentation or the need to drill a pilot hole. 
     (c) to provide a driver that has universal applicability so as to cover a wide range of shank sizes, eye diameters, and end shapes. 
     (d) to provide a driver that aligns the screw axis true to the torque axis for all shank sizes and hanger shapes. 
     Further objects and advantages of the invention are to provide a driver that shortens the installation time and eliminates the fatigue involved in manual installation. Other objects and advantages will become apparent from a consideration of the ensuing description and drawings. 
     SUMMARY OF THE INVENTION 
     A pair of parallel linkage assemblies can be used to maintain the parallel orientation of separately adjustable jaws. Each jaw includes a pair of mutually orthogonal surfaces which function to secure different shank sizes when they are brought together by actuation of an overcenter toggle. The assembly permits a wide variety of hanger shapes and sizes to be installed using a portable electric drill. 
    
    
     DESCRIPTION OF DRAWINGS 
     FIG. 1 is an exploded view of the driver attachment. 
     FIG. 2 is a perspective view illustrating the mechanical interaction involved in simultaneously gripping and centering 
     FIG. 3 is a perspective view of the assembled driver. 
     
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REFERENCE NUMERALS IN DRAWINGS                                            
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10A  left jaw         10B    right jaw                                    
12A  neck locating surface,                                               
                      12B    neck locating surface,                       
     left jaw                right jaw                                    
14A  gripping surface, left jaw                                           
                      14B    gripping surface, right                      
                             jaw                                          
20   left bifilar assembly                                                
                      21     linkage                                      
22   left linkage     22&#39;    right linkage                                
23   linkage          24     linkage                                      
26   left diagonal adjustment                                             
                      26&#39;    right diagonal                               
     member                  adjustment member                            
27   thumb screw      27&#39;    right thumb screw                            
28   left adjustment slot                                                 
                      28&#39;    right adjustment slot                        
29   threaded hole                                                        
30   toggle clamp     32     linkage                                      
34   linkage          36     linkage                                      
38   left linkage     38&#39;    right linkage                                
40   toggle clamp, closure                                                
                      42     closure pin                                  
44   lever            46     closure linkage                              
50   body             52     shank portion of shaft                       
54   slot             56     slot                                         
61   pin              61&#39;    pin                                          
62   pin              62&#39;    pin                                          
63   pin              63&#39;    pin                                          
64   pin              65     pin                                          
72   retaining ring   74     spacer                                       
76   torsion spring   78     eye-bolt                                     
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     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     Referring to the drawings, and particularly FIG. 1, there is shown a pair of jaws comprising a left jaw clement 10A and a right jaw element 10B, each of which is constructed to have left and right complimentary surfaces 12A and 12B for gripping a hanger shaft, and left and right hand clamping surfaces 14A and 14B for retaining the location of the hanger in position when axial thrust is applied. In order to facilitate the gripping of a wide range of shaft sizes, the jaws 10A and 10B must maintain the parallel orientation of these surfaces (12A parallel with 12B) and (14A parallel with 14B) as they move inwardly to engage the shaft. This function is achieved by two separate bifilar configurations, namely a left parallel linkage assembly 20, the motion of which is determined by the location of pins 61, 62, 63 and 64 which define the spatial orientation of the left jaw 10A as it moves toward the right jaw 10B which itself moves parallel to jaw 10A by virtue of the right parallel linkage assembly, its motion being in a like manner determined by the location of pins 61&#39;, 62&#39;, 63&#39; and 64&#39;. 
     The left parallel linkage assembly 20 is comprised of four linkages 21, 22, 23 and 24, jaw 10A, linkage 34, and pins 61, 62, 63 and 64. The right parallel linkage assembly is comprised of complimentary mirror image elements which function identical to the left parallel linkage elements. Both the left and right parallel linkage assemblies include an adjustment feature which functions to change the diagonal distance of travel of the jaws 10A and 10B to accommodate various shank diameters. The left jaw adjustment assembly is comprised of thumb screw 27, and an adjustment member 26 which pivots about pin 64 at the end of body 50 through the slot 56. Member 26 has a slot 28 of sufficient width to accommodate post 62. Advancing thumb screw 27 into the threaded hole 29 of adjustment member 26 shortens the diagonal distance between pin 64 and pin 62 thus moving jaw 10A in the direction of closure. An identical set of mirror image elements allow jaw 10B to be likewise adjusted with respect to pin 62&#39;--in essence, the location of pins 62 and 62&#39; within the slots 28 and 28&#39; of members 26 and 26&#39;&#39;respectively determine the spacing between the jaws 10A and 10B prior to clamp down. The two surfaces 12A and 12B are parallel to each other as are the surfaces 14A and 14B. Preferable these complementation pairs of surfaces are perpendicular to each other so as to optimize the retention force when the jaws 10A and 10B are brought together so that these pairs of surfaces can forcefully engage a hanger shaft as shown in FIG. 2. 
     To recapitulate, the parallelogram type motion of the jaws is produced by the motion of the linkages and pins. Specifically, for the left jaw 10A the forward linkages 21 and 23 of the left parallel linkage assembly 20 rotate about pin 64 over and under the body 50 respectively while the rear linkages 22 and 24 rotate through the same angle about pin 63, over and under the body 50 respectively. A similar corresponding motion of the right jaw 10B is produced by the right parallel linkage components. 
     As seen from FIG. 1, the linkages 32, 34, 36, 38 together with pins 63, 63&#39;, 64, 65 form an over-center toggle clamp 30 which is more particularly described as follows: 
     &#34;Linkages 32 and 34 pivot about pin 64 so as to move outwardly by virtue of linkages 36 and 38 when pin 65 is pulled forward in slot 54 by a torque action against lever 44 which rotates about pin 64. Pin 42 engages closure linkage 46 which communicates the torque applied to lever 44 via pin 65 to linkages 32 and 34 so as to cause the combination of linkages (i.e., 38-22) and (36-22&#39;) to move pins 63 and 63&#39; outwardly. As a consequence the torque applied to the lever 44 is converted to a clamping force between the surfaces 12A and 12B when the left and right bifilar assemblies have been pre-adjusted by thumb screws 27 and 27&#39; to accommodate a particular shaft diameter. It will be understood that the action of toggle clamp 40 is such as to cause pin 65 to slide in slot 54 of body 50 so that both the left and right assemblies remain symmetrically disposed to one another at all times. Closure of toggle damp assembly 40 is thus effectuated via closure pin 42, lever 44, closure linkage 46, pin 65 being pulled toward pin 64 within slot 54 as lever 44 is manually rotated about pin 64 until pin 42 has rotated to a point slightly beyond the center line connecting pins 65 and 64 in order to overcenter lock the apparatus until a manual torque is applied against lever 44 in the opposite direction.&#34; 
     Retaining rings or keepers (i.e., 72) are used throughout to hold the assembly together. Spacer 74 occupies the gap which exists between linkage 36 and closure linkage 46. Torsion spring 76 wraps around the extended portion of pin 63, and end of spring 76 being arranged to push upon the extended portion of pin 62 to bias the parallel linkage assembly toward the open parallelogram position. The other end of spring 76 pushes against the extended portion of pin 65 so as to urge toggle damp assembly 30 toward the open jaw position, these biases having a tendency to make the adjustment and loading easier. 
     From the description above, a number of advantages are readily apparent: 
     (a) the device is universally functional, and can be used with any standard manual or power drill. 
     (b) the invention eliminates the need to pound or drill a starting hole. 
     (c) the device can be made in different sizes--to cover a vast variety of hangers. 
     (d) the assembly will drive the screw axis true to the driving axis regardless of the shank diameters or hanger configuration. 
     OPERATION 
     Adverting again to FIG. 1, the typical procedure for using the invention would involve the steps of inserting the drive shaft 52 in a conventional portable drill chuck (not shown). The shank portion of the hanger is then positioned between jaws and the two thumb screws 27 and 27&#39; adjusted equally so that the two jaws 10A and 10B will center the hanger screw axis in line with the rotational axis of shaft 52 when lever 44 is operated to close. Once this pre-adjustment is made, lever 44 can be rotated to secure the shank; thereafter, for a given size shank, no further adjustments are necessary. FIG. 2 shows the position of the jaws 10A and 10B as they would appear after lever 44 is moved so as to lock the shank of the eye-bolt 78. 
     SCOPE 
     The apparatus disclosed herein is versatile and convenient. It eliminates the need to hammer start (or drill holes) and it eliminates the time intensive task of manual installation. 
     Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but merely as descriptive of a preferred embodiment. For example, lever 44 can pivot from pin 65 capturing pin 63 at mid point then extend outward instead of closer to toggle clamp 30; shank portion of drive shaft 52 can be hexagonal instead of round; two separate compression springs, one in adjuster diagonal 26 to push against pin 62, the other in body 50 pushing against pin 65 to do the same work as torsion spring 76, etc. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the example given.