Abstract:
A locking wedge system for use with a load-carrying stud having a locknut (or work piece) mounted on the stud in locking relation with another work piece employs a laterally displaceable laterally tapered wedge member that is forced transversely into axial jacking relation between a pair of tapered washers so as to apply a large axial locking force against the lock nut and work piece. The tapered wedge member is forced into engagement between the pair of tapered washers by way of a transversely extending jacking screw. The jacking screw may pull or push the tapered wedge member into or out of engagement between the pair of tapered washers. A preferred wedge angle from normal to the stud is 3 degrees with an operating range from 1 degree to 10 degrees. The locking wedge system elements are selectively rotatable about the stud, for optimum operating access to the jacking screw.

Description:
FIELD OF THE INVENTION 
     This invention is directed to locking assemblies and in particular locking assemblies for anchoring two members mounted on a threaded stud. 
     BACKGROUND OF THE INVENTION 
     A threaded nut or work piece is frequently locked to a threaded stud by applying a second nut or work piece in direct, face-to-face compressive relation against the first nut or work piece, to lock it in place. Traditionally, the two threaded members must be rotated (torqued) against each other in the fastening process, upon the threaded stud. The threaded stud is slightly stretched during this fastening process, in order to generate the required locking force between the locking nut and the work piece. In the case of large diameter threaded assemblies (e.g. 1″ diameter or larger) the torque required to produce the desired fastening effect become significant, and in some cases is impractical by standard hand tools. Instruments such as a load-meter, which are required to be locked in place, are unsuited to having such locking torque applied against them, and can be damaged by such torquing action. 
     In installations where the threaded stud is subjected to a large applied tensile load, the axial locking force at the locking interface must exceed the applied tensile load in order to ensure that the locked condition is maintained. This may require the application of excessive mutually opposed torquing force between the nut and the workpiece. Furthermore, some work pieces may be torque-sensitive and not suited or permitted to be tightened with such excessive torque, for example, such as an inline force transducer (load-meter) located in a load-applying tensile testing apparatus. However, a reliable locking mode is still desirable for these types of assembly. 
     An adjustable spacer, known as the “MTS 6011.11 Spiral Washers “has previously been used to provide a backlash-free threaded union. The MTS apparatus uses a pair of spirally tapered washers in facing relation, one of which is rotated about its polar axis relative to the other tapered washer, to change the extent of taper interplay, thereby increasing the axial extent of the washers, to take up the extension of a stud or other tensioned member. However, the Spiral Washers are NOT load jacking devices. Four major disadvantages of the MTS system are: (1) External tension force is needed to stretch the stud as the MTS Washers are not usable as a load-applying prime mover; (2) the requirement for special tools in order to rotate one washer relative to the other: (3) the MTS system may require the use of two hands; and (4) in order to access the washers and use the special tools in rotating the washer/washers a significant clear area adjacent the washers is required. 
     SUMMARY OF THE INVENTION 
     In the present invention a locking force being applied to an assembly of a first member and a second member, such as two work pieces secured to a tensioned member such as a threaded stud, or such as a work piece and a lock nut both mounted upon a threaded stud, or such as an unthreaded first member supported by an abutment and a threaded second member secured to a threaded stud, is provided by way of a locking wedge system mounted upon the stud in interposed, snugged-up (hand-tightened) relation between the first member and the second member. 
     The locking assembly has a pair of axially slideable, laterally tapered washers mounted on the stud, with a laterally tapered wedge member in partial laterally withdrawn, taper-face to taper-face relation between the two washers. 
     To apply locking force to the whole assembly, the tapered wedge member is forced laterally into linear wedging relation with the adjoining two tapered washers by a wedge displacer so as to force the washers apart and thus apply axial loading by the locking wedge system against the adjoining work piece and the securing nut, (or against the two secured work pieces), thereby locally tensioning the stud. A wedge displacer may also be used to force the tapered wedge member out from between the opposing tapered washers. In the claims of this specification the term locking wedge displacer means a wedge displacer for axially loading the stud, the term unlocking wedge displacer means a wedge displacer for axially unloading the stud, and the term wedge displacer means a wedge displacer which can be used to axially load and unload the stud. In various embodiments different wedge displacers may be necessary for loading and unloading the stud and in various embodiments the same wedge displacer may be used to load and unload the stud. 
     The wedge displacer may comprise an abutment located adjacent the stud and a force transfer element for pulling or pushing the tapered wedge member into increased or decreased engagement with the opposing tapered washers. In various aspects the abutment may be secured or supported by the opposing tapered washers, the first and second members or external parts such as parts of a machine to which the stud is connected, or any combination. In one aspect the force transfer element is a threaded screw also referred to as a jacking screw. In one aspect the abutment has a through bore supporting a threaded jacking screw that extends transversely of the stud and contacts the tapered wedge member in force applying connection, to displace it laterally of the stud in wedging relation between the tapered washers 
     In one aspect the through bore is a clearance bore and the threaded jacking screw extends through the clearance bore in the abutment, to engage a threaded aperture in the tapered wedge member, to enable it to be pulled by rotation of the jacking screw into increased wedging engagement between the tapered washers, with the head of the screw being stabilized by engagement with the outer face of the abutment, adjacent the bore. 
     In another aspect the through bore is a threaded bore with the threaded jacking screw in threaded relation with the through bore of the abutment, and protrudes therethrough into lateral pushing engagement with the tapered wedging member, to push it into axial wedging relation with the tapered washers. 
     The tapered wedge member may be retained in-situ by the force applying means. In some cases the locking wedge displacer will need to remain in place to retain the tapered wedge member in axial loading, especially for higher wedge angles. In other cases the tapered wedge member will remain in place after locking wedge member is removed. In these latter cases the tapered wedge member may be able to be released from axial loading by means other than an unlocking wedge displacer but damage to the locking wedge system is unlikely when an unlocking wedge displacer is used. Further, while other prior art tools may be able to release the tapered wedge member from axial loading, prior art tools will not be able to merely reduce axial loading without fully releasing axial loading. 
     The torque required to rotate the threaded jacking screw in displacing the tapered wedge member laterally in its load applying mode is but a fraction of the torque force required to directly rotate a stud nut or work piece in providing the same stud tension loading as that provided by the locking wedge system. 
     The subject system enables the adoption of wedging angles that generate sufficient stud stretching, when the tapered wedge member is displaced laterally, without the need to stretch the stud by other means before tightening the locking wedge system. 
     A further advantage of the subject system is that a significantly greater length of the stud is tensioned by the force-applying process, due to the interposition between the nut and the work piece of the locking wedge system, as compared to the miniscule length of stud involved when the stud-tensioning members (such as a nut and a work piece) are torqued against each other, face-to-face. This greater length of tensioned stud involved with the present invention means that much greater strain energy is stored in the stud, for a given applied axial loading. 
     Some particular advantages of the present invention include the fact that the wedging action of the subject locking wedge system is a linear displacement, thereby minimizing the requirement for access space about the installation, and that only a low input torque is required to actuate the locking wedge system, which enables the use of an Allen Key™ to turn the threaded screw in applying the locking force to lock up the assembled components. Also, the tapered washers and the tapered wedge member can be selectively rotatably oriented about the stud member prior to lock-up, thereby enabling the locking wedge system to be operated from a selected, extremely limited access location, by the mere insertion and operation of an Allen Key in the wedge actuating screw. In extremely constricted quarters a straight screwdriver may be used, with preference being given to the square-headed Robertson™ rather than the cruciform Phillips™ screw and screwdriver. 
     In an application of the locking wedge system, such as a tensile testing machine wherein a metal test rod may be inserted in the machine and tensioned to the point of failure, the machine has a load cell mounted to a stud and locked by way of a locking nut or equivalent shoulder abutment, having the present locking wedge system interposed between the load cell and the locking nut or equivalent abutment, thereby avoiding the application of torque to the load cell. 
     For reliable operation, the locking force applied by the subject locking wedge system to the stud-mounted components needs to exceed the load being applied by the machine to the test piece. This degree of locking force may be readily provided by the locking wedge system in accordance with the present invention. 
     With the knowledge of the maximum working load value that will be applied to machine, such as a tensile testing machine, then based upon the dimensions of the tension-loaded member, such as a stud, the maximum working stress can be readily calculated. Increasing this maximum working stress value by a ‘reserve’ factor then gives the desired locking stress to be exerted by the present locking wedge system. This value can then be readily calculated by any competent Engineer, and converted into a desired wedge angle necessary to achieve the desired result. 
     The application of friction-diminishing coatings such as Teflon™ to the interacting wedge faces will then reduce the torque loading that is required to operate the subject locking device. 
     A prototype locking wedge system was designed and made based on the following Calculations and design specifications with the pair of opposing tapered washers and cooperating tapered wedge member having a three (3°) degree taper: 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 Stud tension force target 
                 Fc = 25,000 lb 
               
               
                 Tapered wedge member angle 
                 A = 3° per side 
               
               
                 Stud effective length in tension 
                 L = 4.5 in 
               
               
                 Threaded stud size 
                 1¼″-12 SAE thread 
               
               
                 Lateral clamp screw size: 
                  7/16″-20 Grade 8 socket head screw 
               
               
                   
               
             
          
         
       
     
     The following parameters are known: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Young&#39;s modulus of steel 
                 E = 29,000,000 lb/in 2   
               
               
                   
                 Stud stress area 
                 As = 1.0729 in 2   
               
               
                   
                 Stud material strength (Grade 5) 
                 S = 74,000 lb/in 2   
               
               
                   
                 Clamp screw specified clamp force 
                 N = 10,700 lb 
               
               
                   
                 Coefficient of friction (lubricated) 
                 C = 0.16 
               
               
                   
                   
               
             
          
         
       
     
     The following calculations are performed:
         Requested stud elongation
 
Δ L=Fc /( EAs )=25,000/(29,000,000×1.0729)=0.0008in/in
   Minimum wash lateral travel
 
 T=ΔL L /(2 Sin( A ))=0.0008×4.5/(2×0.052)=0.035in
   Requested lateral force to generate target tension
 
 Fl= 2 Fc  Sin( A )=2×25,000×0.052=2600lb.
   Washer surface frictions under clamp force
 
 Ff= 2 FcC= 2×25,000×0.16=8,000lb
   Total request lateral clamp force
 
 F=Fl+Ff= 2600+8000=10,600lb.
       

     The above mentioned prototype washer assembly with 3 degree wedge angles was tested in a mechanical laboratory. With calculated lateral clamp force applied, the target stud tension was obtained. The actual lateral travel of the tapered washer was slightly higher than the calculated value due to simplified calculation of stud geometry. The invention was proved to be working, based on the testing results. 
     Since the specified 7/16″ screw clamp force N is 10,700 lbs, a washer assembly with 3 degree wedge angles will be able to generate the target stud tension of 25,000 lb. 
     The above example calculations have shown that approximately 75% of lateral clamp force is utilized to overcome surface friction between washers. The application of friction diminishing coatings such as Teflon™ to the interacting wedge faces will then reduce the torque loading that is required to operate the subject locking device. 
     With the knowledge of the maximum working load value that will be applied to a system, such as a tensile testing machine, the above calculation can be used in any stud sizes with given target stud tension forces by controlling the amount of lateral displacement of the tapered wedge member. 
     The selected wedge angles must be within a certain range in order to function properly. If the angle is too small, excessive lateral travel of the tapered wedge member will result. Without significantly increasing the compact size of a given size of locking wedge system, at a corresponding cost increase, this may impair support rigidity. Among other things, the tapered faces of the tapered washers and the tapered wedge member will lose significant surface contact area, especially adjacent the tensioned stud, lateral travel is too great. On the other hand when the angle is too large, the required lateral clamp force will be increased to an impractical level. Among other things, the amount of force required to laterally displace the tapered wedge member will eventually approach or exceed the amount of force needed to tension the stud directly. Further, as the wedge angle goes up the size and cost of the jacking screw and corresponding abutment and tapered wedge member, and the locking wedge system as a whole, will increase to impractical levels. 
     Given the broad range of potential uses of the inventive locking wedge system a useful range of wedge angles would be from one (1) degree to ten (10) degrees, especially if friction reducing coatings are used as the wedge angle increases, as shown by the following calculations (without taking into account anti-friction coatings). 
     The following are the calculation and design Specification for the locking wedge system with a high preload (20,000 lb) for the pair of opposing washers and cooperating tapered wedge member having a one (1°) degree tapers: 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 Stud tension force target 
                 Fc = 20,000 lb 
               
               
                 Stud effective length in tension 
                 L = 4 in 
               
               
                 Tapered wedge member angle 
                 A = 1° per side 
               
               
                 Threaded stud size 
                 1-12 SAE thread 
               
               
                 Lateral clamp screw size: 
                  7/16″-20 Grade 8 socket head screw 
               
               
                   
               
             
          
         
       
     
     The following parameters are known: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Young&#39;s modulus of steel 
                 E = 29,000,000 lb/in 2   
               
               
                   
                 Stud stress area 
                 As = 0.663 in 2   
               
               
                   
                 Stud material strength (Grade 5) 
                 S = 85,000 lb/in 2   
               
               
                   
                 Clamp screw specified clamp force 
                 N = 10,700 lb 
               
               
                   
                 Coefficient of friction (lubricated) 
                 C = 0.16 
               
               
                   
                   
               
             
          
         
       
     
     Calculations:
         Requested stud elongation
 
Δ L=Fc /( EAs )=20,000/(29,000,000×0.663)=0.001in/in
   Minimum wash lateral travel
 
 T=ΔL L /(2 Sin( A ))=0.001×4/(2×0.0175)=0.114in
   Requested lateral force to generate target tension
 
 Fl= 2 Fc  Sin( A )=2×20,000×0.0175=700lb.
   Washer surface frictions under clamp force
 
 Ff= 2 FcC= 2×20,000×0.16=6,400lb
   Total request lateral clamp force
 
 F=Fl+Ff= 600+6400=7,000lb.
       

     Since the specified 7/16″ screw maximum clamp force N is 10,700 lb. a washer assembly with 1 degree wedge angle will be able to generate the target stud tension of 20,000 lb. The requested operation torque on 7/16″ screw is about 55 ft-lb. 
     The following are the calculations and design Specification for the locking wedge system with a high preload (20,000 lb) for the pair of opposing washers and cooperating tapered wedge member having ten (10°) degree tapers: 
     Design specification: 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 Stud tension force target 
                 Fc = 10,000 lb 
               
               
                 Stud effective length in tension 
                 L = 5 in (thicker washers) 
               
               
                 Tapered wedge member angle 
                 A = 10° per side 
               
               
                 Threaded stud size 
                 1-12 SAE thread 
               
               
                 Lateral clamp screw size: 
                  7/16″-20 Grade 8 socket head screw 
               
               
                   
               
             
          
         
       
     
     The following parameters are known: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Young&#39;s modulus of steel 
                 E = 29,000,000 lb/in 2   
               
               
                   
                 Stud stress area 
                 As = 0.663 in 2   
               
               
                   
                 Stud material strength (Grade 5) 
                 S = 85,000 lb/in 2   
               
               
                   
                 Clamp screw specified clamp force 
                 N = 10,700 lb 
               
               
                   
                 Coefficient of friction (lubricated) 
                 C = 0.16 
               
               
                   
                   
               
             
          
         
       
     
     Calculations:
         Requested stud elongation
 
Δ L=Fc /( EAs )=10,000/(29,000,000×0.663)=0.0005in/in
   Minimum wash lateral travel
 
 T=ΔL L /(2 Sin( A ))=0.0005×5/(2×0.174)=0.007in
   Requested lateral force to generate target tension
 
 Fl= 2 Fc  Sin( A )=2×10,000×0.174=3480lb.
   Washer surface frictions under clamp force
 
 Ff= 2 FcC= 2×10,000×0.16=3,200lb
   Total request lateral clamp force
 
 F=Fl+Ff= 3480+3200=6,680lb.
       

     Since the specified 7/16″ screw maximum clamp force N is 10,700 lb, a washer assembly with a ten (10) degree wedge angle will be able to generate the target stud tension of 10,000 lb. The requested operation torque on 7/16″ screw is about 53 ft-lb. 
     On the other hand wedge angles of less than 0.3 degrees or more than 15 degrees will be of little or no use as shown by the following calculations. 
     The following are the calculations and design Specification for the locking wedge system with a high preload (20,000 lb) for the pair of opposing tapered washers and cooperating tapered wedge member having zero point three (0.3°) degree tapers: 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 Stud tension force target 
                 Fc = 25,000 lb 
               
               
                 Tapered wedge member angle 
                 A = 0.3° per side 
               
               
                 Stud effective length in tension 
                 L = 4.5 in 
               
               
                 Threaded stud size 
                 1¼″-12 SAE thread 
               
               
                 Lateral clamp screw size: 
                  7/16″-20 Grade 8 socket head screw 
               
               
                   
               
             
          
         
       
     
     The following parameters are known: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Young&#39;s modulus of steel 
                 E = 29,000,000 lb/in 2   
               
               
                   
                 Stud stress area 
                 As = 1.0729 in 2   
               
               
                   
                 Stud material strength (Grade 5) 
                 S = 74,000 lb/in 2   
               
               
                   
                 Clamp screw specified clamp force 
                 N = 10,700 lb 
               
               
                   
                 Coefficient of friction (lubricated) 
                 C = 0.16 
               
               
                   
                   
               
             
          
         
       
     
     The following calculations are performed:
         Requested stud elongation
 
Δ L=Fc /( EAs )=25,000/(29,000,000×1.0729)=0.0008in/in
   Minimum wash lateral travel
 
 T=ΔL L /(2 Sin( A ))=0.0008×4.5/(2×0.0052)=0.35in
   Requested lateral force to generate target tension
 
 Fl= 2 Fc  Sin( A )=2×25000×0.0052=260lb.
   Washer surface frictions under clamp force
 
 Ff= 2 FcC= 2×25,000×0.16=8,000lb
   Total request lateral clamp force
 
 F=Fl+Ff= 260+8000=8,260lb.
       

     The following are the calculations and design Specification for the locking wedge system with a high preload (20,000 lb) for the pair of opposing tapered washers and cooperating tapered wedge member having Fifteen (15°) degree tapers: 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 Stud tension force target 
                 Fc = 25,000 lb 
               
               
                 Tapered wedge member angle 
                 A = 15° per side 
               
               
                 Stud effective length in tension 
                 L = 4.5 in 
               
               
                 Threaded stud size 
                 1¼″-12 SAE thread 
               
               
                 Lateral clamp screw size: 
                  7/16″-20 Grade 8 socket head screw 
               
               
                   
               
             
          
         
       
     
     The following parameters are known: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Young&#39;s modulus of steel 
                 E = 29,000,000 lb/in 2   
               
               
                   
                 Stud stress area 
                 As = 1.0729 in 2   
               
               
                   
                 Stud material strength (Grade 5) 
                 S = 74,000 lb/in 2   
               
               
                   
                 Clamp screw specified clamp force 
                 N = 10,700 lb 
               
               
                   
                 Coefficient of friction (lubricated) 
                 C = 0.16 
               
               
                   
                   
               
             
          
         
       
     
     The following calculations are performed:
         Requested stud elongation
 
Δ L=Fc /( EAs )=25,000/(29,000,000×1.0729)=0.0008in/in
   Minimum wash lateral travel
 
 T=ΔL L /(2 Sin( A ))=0.0008×4.5/(2×0.259)=0.007in
   Requested lateral force to generate target tension
 
 Fl= 2 Fc  Sin( A )=2×25,000×0.259=12,950lb.
   Washer surface frictions under clamp force
 
 Ff= 2 FcC= 2×25,000×0.16=8,000lb
   Total request lateral clamp force
 
 F=Fl+Ff= 12,950+8,000=20,950lb.
       

     Those skilled in the art will be able to determine useful wedge angles for any given application. 
     The various elements of an apparatus such as a tensile testing machine may involve the use of a number of the subject locking mechanisms, interposed between elements of the mechanism. 
     The invention therefore includes a locking wedge system for locking a first member to a second member in axially fixed spaced relation along a stud, at least the first member threadedly mounted on the stud, the system comprising a pair of laterally tapered washers, each having a laterally tapered inner face facing the other tapered washer for mounting in axially displaceable relation on the stud between the first member and the second member, a laterally tapered wedge member, having opposing tapered faces, for mounting on the stud between the pair of tapered washers, each of the opposing tapered faces for slidably engaging the inner face of one of the two tapered washers, the tapered wedge member being laterally displaceable relative to the stud and to the tapered washers, and a locking wedge displacer for laterally displacing the tapered wedge member from an unlocked position wherein the stud is not axially tensioned to a locked position wherein the stud is axially tensioned. 
     In one aspect of the locking wedge system the locking wedge displacer pulls the tapered wedge member between the pair of tapered washers for increasing the axial tension on the stud. In one aspect of the locking wedge system the locking wedge displacer pushes the tapered wedge member between the pair of tapered washers for increasing the axial tension on the stud. In one aspect the locking wedge system further comprises an unlocking wedge displacer for laterally displacing the tapered wedge member from a locked position wherein the stud is axially tensioned to an unlocked position wherein the stud is not axially tensioned. In one aspect of the locking wedge system the unlocking wedge displacer pulls the tapered wedge member out from between the pair of tapered washers for decreasing or releasing the axial tension on the stud. In one aspect of the locking wedge system the unlocking wedge displacer pushes the tapered wedge member out from between the pair of tapered washers for decreasing or releasing the axial tension on the stud. 
     In one aspect of the locking wedge system the locking wedge displacer and the unlocking wedge displacer comprise one wedge displacer. In one aspect of the locking wedge system the wedge displacer comprises an abutment, the abutment for supporting a force transfer element for engaging the tapered wedge member for laterally displacing the tapered wedge member. In one aspect of the locking wedge system the force transfer element is a threaded screw. In one aspect of the locking wedge system the abutment is secured by the pair of tapered washers. In one aspect of the locking wedge system each tapered washer comprises a shouldered recess for receiving the abutment, the abutment further comprising corresponding shoulders. In one aspect of the locking wedge system the threaded screw is rotatably secured to the tapered wedge member and the threaded screw threadedly engages the abutment for moving the tapered wedge member in between and out from between the tapered washers in unison with the threaded screw. 
     In another aspect of the locking wedge system locking wedge displacer comprises an abutment and a threaded screw, the abutment for rotatably supporting the threaded screw and the threaded screw for engaging the tapered wedge member. In one aspect of the locking wedge system a thinner end of the tapered wedge member comprises a lateral threaded locking aperture for engaging the threaded screw. In another aspect of the locking wedge system the unlocking wedge displacer comprises an abutment and a threaded screw, the abutment for rotatably supporting the threaded screw and the threaded screw for engaging the tapered wedge member. In one aspect of the locking wedge system a thicker end of the tapered wedge member comprises a lateral threaded unlocking aperture for engaging the threaded screw. In one aspect the locking wedge system further comprises a clearance bore in a bridge portion of the abutment through which the threaded screw extends, the threaded screw having an enlarged head supported by the bridge portion of the abutment. In one aspect of the locking wedge system the abutment is supported by the pair of tapered washers. In one aspect of the locking wedge system each of the pair of tapered washers comprises a recess for locating the abutment. 
     In another aspect of the locking wedge system the locking wedge displacer comprises an abutment and a threaded screw, the abutment for rotatably supporting the threaded screw and the threaded screw for engaging a thicker end of the tapered wedge member. In one aspect of the locking wedge system a thicker end face of the tapered wedge member comprises a centering recess for engaging a tip of the threaded screw. In one aspect of the locking wedge system the unlocking wedge displacer comprises an abutment and a threaded screw, the abutment for rotatably supporting the threaded screw and the threaded screw for engaging a thinner end of the tapered wedge member. In one aspect of the locking wedge system a thinner end face of the tapered wedge member comprises a centering recess for engaging a tip of the threaded screw. In one aspect of the locking wedge system the abutment has a threaded bore through which the threaded screw is threadedly engaged. In one aspect of the locking wedge system the abutment is secured by the pair of tapered washers. In one aspect of the locking wedge system each of the pair of tapered washers comprises a recess for locating the abutment. In one aspect of the locking wedge system the recess comprises a shouldered recess for receiving corresponding shoulders on the abutment. 
     The invention also includes a locking wedge system for locking a first member to a second member in axially fixed spaced relation along a stud, at least the first member threadedly mounted on the stud, the system comprising a pair of laterally tapered washers, each tapered washer having an inner face, mounted in axially displaceable relation on the stud between the first member and the second member, a laterally tapered wedge member, having opposing tapered faces, mounted on the stud between the pair of tapered washers, each of the opposing tapered faces for slidably engaging the inner face of one of the two tapered washers, the tapered wedge member being laterally displaceable relative to the stud and to the tapered washers, and a wedge displacer for laterally displacing the tapered wedge member from an unlocked position wherein the stud is not axially tensioned to a locked position wherein the stud is axially tensioned and for laterally displacing the tapered wedge member from a locked position wherein the stud is axially tensioned to an unlocked position wherein the stud is not axially tensioned. 
     In one aspect of the locking wedge system the wedge displacer comprises an abutment, the abutment for supporting a force transfer element for engaging the tapered wedge member for laterally displacing the tapered wedge member. In one aspect of the locking wedge system, the force transfer element is a threaded screw. In one aspect of the locking wedge system the abutment is secured by the pair of tapered washers. In one aspect of the locking wedge system the pair of tapered washers each comprises opposing shouldered recesses for receiving corresponding shoulders on the abutment, the abutment for supporting the threaded screw for locking and unlocking the tapered wedge member. In one aspect of the locking wedge system the abutment has a threaded bore for threadedly engaging the threaded screw, the threaded screw for pushing the tapered wedge member in between and out from between the tapered washers. In one aspect of the locking wedge system the thicker end face and the thinner end face of the tapered wedge member comprise centering recesses for receiving the tip of the threaded screw. In one aspect of the locking wedge system the abutment is supported by the pair of tapered washers and a thinner end of the tapered wedge member comprises a lateral threaded locking aperture for engaging the threaded screw for locking the tapered wedge member and a thicker end of the tapered wedge member comprises a lateral threaded unlocking aperture for engaging the threaded screw for unlocking the tapered wedge member. In one aspect the locking wedge system further comprises a clearance bore in a bridge portion of the abutment through which the threaded screw extends, the threaded screw having an enlarged head supported by the bridge portion of the abutment, the threaded screw for pulling the tapered wedge member in between and out from between the tapered washers. 
     In another aspect of the locking wedge system one of the opposing tapered faces of the tapered wedge member and the corresponding inner face of one of the two tapered washers slidably engage at a first wedge angle and the other of the opposing tapered faces of the tapered wedge member and the corresponding inner face of the other of the two tapered washers slidably engage at a second wedge angle. In one aspect of the locking wedge system the sum of the first wedge angle and the second wedge angle is between two degrees and twenty degrees. In one aspect of the locking wedge system the first wedge angle is as low as zero degrees and the second wedge angle is as high as twenty degrees. In one aspect of the locking wedge system the first wedge angle and the second wedge angle are an identical wedge angle. In one aspect of the locking wedge system the identical wedge angle is between one and ten degrees. In one aspect of the locking wedge system the identical wedge angle is approximately three degrees. 
     In another aspect of the locking wedge system the inner face of each of the tapered washers and the opposing tapered faces of the tapered wedge member comprise a friction reducing coating. In one aspect of the locking wedge system the friction reducing coating is TEFLON. 
     In another aspect of the locking wedge system the tapered washers and the tapered wedge member are selectively rotatable about the stud, to facilitate access to the wedge displacer. 
     In another aspect of the locking wedge system the second member is threadedly mounted on the stud. In another aspect of the locking wedge system the first member and the second member are workpieces. In another aspect of the locking wedge system one of the first member and the second member is a locknut. 
     In another aspect of the locking wedge system the abutment is supported by the first member and the second member. 
     In another aspect of the locking wedge system the threaded screw further comprises means for rotating the threaded screw. In one aspect of the locking wedge system the means for rotating the threaded screw comprise a head. In one aspect of the locking wedge system the head is adapted to receive one of the group consisting of an alien key, a wrench and a screwdriver. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Certain embodiments of the invention are illustrated, by way of example, without limitation of the invention thereto, other than as set forth in the accompanying claims; it being understood that further embodiments may be understood by one skilled in the art. 
       Reference is made to the accompanying drawings, wherein: 
         FIG. 1  is a side elevational view of a first embodiment of the locking wedge system; 
         FIG. 2  is a top plan view of the tapered washer of  FIG. 1 ; 
         FIG. 3  is a top plan view of the tapered wedge member of  FIG. 1 ; 
         FIG. 4  is a top plan view of a second embodiment of the locking wedge system; 
         FIG. 5  is a perspective view of the locking wedge system of  FIG. 4 ; 
         FIG. 6  is a side elevational view of a portion of a tensile testing machine incorporating two locking wedge systems of  FIG. 1 ; and 
         FIG. 7  is a side elevational view of a portion of a tensile testing machine having a pivotal attachment incorporating the locking wedge system of  FIG. 1 ; 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , in this first embodiment a threaded workpiece W is threaded onto a threaded stud  10 , having a locknut  12  threaded onto the stud  10 , in axially spaced relation with the workpiece W. Interposed between the nut  12  and the workpiece W is a subject locking wedge system  13  having a pair of tapered washers  14 ,  14 ′, each having a washer aperture  15  with a clearance fit for mounting on stud  10 . Tapered washers each have an angle of taper T. The inner face  12 ′ of the nut  12  and inner face W′ of workpiece W bear against the adjoining outer faces  42 , of tapered washers  14 ,  14 ′. The washers  14 ,  14 ′ are separated by a tapered wedge member  16 , having opposing faces  40  that each have cooperating angle of taper T, the same as the angle of taper T of the cooperating inner faces of tapered washers  41  of tapered washers  14 ,  14 ′. The outer faces of tapered washers  42  of tapered washers  14 ,  14 ′ are typically, but do not necessarily need to be, normal to the polar axis of the threaded stud  10  and mutually parallel. The tapered wedge member  16  has a thinner end  16 A and a thicker end  16 B, in accordance with its tapered geometry. Tapered wedge member  16  has an elongated wedge aperture for mounting on stud  10  between thinner end  16 A and thicker end  16 B. 
     In one aspect of the invention the wedging force applied by the opposing faces  40  of tapered wedge member  16  against the adjoining tapered inner faces of tapered washers  41  of tapered washers  14 ,  14 ′ is applied as a laterally directed tensile force, drawing the thinner end  16 A of tapered wedge member  16  laterally into wedging relation with tapered washers  14 ,  14 ′ to cause their mutual separation. The tensile drawing force is applied by a locking jacking screw  18  that is threaded into threaded locking aperture  22  of thinner end  16 A of the tapered wedge member  16  through clearance bore  31  in bridge portion  29  in locking pull abutment  24  which straddles thicker ends  14 A of tapered washers  14 ,  14 ′. Locking pull abutment  24  has an unthreaded clearance bore  31  in bridge portion  29  through which locking jacking screw  18  extends. The locking jacking screw head  20  of locking jacking screw  18  abuts the outer surface  24 ′ of locking pull abutment  24 , to secure locking pull abutment  24  in place, and to contain the force generated by locking jacking screw  18  as it is tensioned. Locking pull abutment  24  may have opposing foot portions  28  attached to bridge  29  if required to allow additional lateral travel for tapered wedge member  16 . 
     Shown in phantom in  FIG. 1 , located diametrically opposite from the locking pull abutment  24 , is unlocking jacking screw  30  threadedly engaging threaded unlocking aperture  22 ′ in the thicker end  16 B of the tapered wedge member  16 . The unlocking jacking screw head  32  of unlocking jacking screw  30  is in engagement with unlocking pull abutment  26  that straddles the thinner ends  14 B of tapered washers  14 ,  14 ′. Unlocking pull abutment  26  may have opposing foot portions  28  attached to bridge  29  if required to allow additional lateral travel for tapered wedge member  16 . 
     In use, with the locking jacking screw  18  and locking pull abutment  24  removed or loosened, tapered wedge member  16  may be unlocked from tapered washers  14 ,  14 ′ by unlocking jacking screw  30  and unlocking pull abutment  26  which can be assembled in place as illustrated, with unlocking jacking screw  30  screwed into the thicker end  16 B of tapered wedge member  16  through clearance bore  31  in bridge portion  29  of unlocking pull abutment  26  with unlocking pull abutment  26  supported by the thinner ends  14 B of tapered washers  14 ,  14 ′, and then rotating unlocking jacking screw head  32  so as to release the assembled upper lock nut  12  from its load bearing relation with the workpiece W. The unlocking jacking screw head  32  of unlocking jacking screw  30  abuts the outer surface  26 ′ of unlocking pull abutment  26 , to secure unlocking pull abutment  26  in place, and to support the force generated by unlocking jacking screw  30  as it is tensioned in the unlocking process. 
     Referring also to  FIGS. 2 and 3 ,  FIG. 2  shows washers  14 ,  14 ′, each having a washer aperture  15  which has a clearance fit for stud  10  (not shown). Both tapered washers  14 ,  14 ′ have locking recesses  25 , located in the thick ends  14 A of tapered washers  14 ,  14 ′ within which locking recesses  25  foot portions  28  of locking pull abutment  24  are positioned, for stabilizing locking jacking screw  18  when tightening the locking wedge system  13 . 
     The locking pull abutment  24  is held in anchored relation within the locking recesses  25  by the engagement and tightening of locking jacking screw  18  (not shown) into threaded wedge member  16  (not shown). Unlocking recesses  27  in the thinner ends  14 B of washers  14 ,  14 ′ receive foot portions  28  of the unlocking pull abutment  26  (shown in phantom), which straddles tapered washers  14 ,  14 ′. The withdrawal jacking screw  30  (illustrated as a separate entity from locking jacking screw  18  for purposes of clarification) is located and secured by the unlocking pull abutment  26  in the same fashion as the locking jacking screw  18 , described above. 
       FIG. 3  shows tapered wedge member  16  having a laterally elongated wedge aperture  17 , preferably ovoid for studs with round cross-sections, through which the stud  10  (not shown) extends, the axis of elongation of the ovoid aperture being aligned with the axis of taper of tapered wedge member  16 . The thinner end  16 A of the tapered wedge member  16  has a lateral threaded locking aperture  22  to receive locking jacking screw  18  in threaded relation therein. The locking jacking screw head  20  of the jacking screw  18  is positioned against the outer surface  24 ′ of locking pull abutment  24  which straddles thicker ends  14 A of tapered washers  14 ,  14 ′ (see  FIG. 1 ), the locking jacking screw  18  extending through a clearance bore  31  in the bridge portion  29  of locking pull abutment  24 . 
     Clockwise rotation of a right-hand threaded locking jacking screw  18  causes the screw  18  to advance into tapered wedge member  16 . Due to the axial restraint imposed on locking jacking screw  18  by the locking pull abutment  24 , this rotation of the locking jacking screw  18  draws tapered wedge member  16  into deeper wedging relation between tapered washers  14 ,  14 ′, thereby applying compressive force from tapered washers  14 ,  14 ′ against the inside face of nut  12 ′ and the inside face of workpiece W′. 
     This wedging action produces a significantly amplified axial force and reactive force, operating on the nut  12  and the work piece W, acting in a separating sense. This enhanced axial force acting upon nut  12  generates increased frictional engagement of threads of nut  12  with the threads of the stud  10 , so as to further resist any tendency for the lock nut  12  to back-off. 
     Shown in phantom in  FIG. 1 , an unlocking jacking screw  30  may be inserted into threaded unlocking aperture  22 ′ recessed into the thicker end  16 B of tapered wedge member  16 . An unlocking pull abutment  26  straddles the thinner ends  14 B of tapered washers  14 ,  14 ′ and stabilizes unlocking jacking screw  30 , enabling it to be screwed into tapered wedge member  16 . With locking jacking screw  18  backed off, so as to provide a clearance between the head of locking jacking screw  18  and the locking pull abutment  24 , the unlocking jacking screw  30  may be tightened up, thereby withdrawing tapered wedge member  16  outwardly (see  FIG. 1 ), to diminish or terminate the jacking action of tapered wedge member  16 . With tapered wedge member  16  withdrawn out of wedging action with tapered washers  14 ,  14 ′, the unloaded stud/nut/workpiece assembly  10 / 12 /W may be readily disassembled. 
     Turning to the  FIGS. 4 and 5 , in this second embodiment of the locking wedge system, tapered washers  43 ,  43 ′ have shouldered locking recesses  50 , to receive and contain locking push abutment  52 , that slide longitudinally into the shouldered locking recesses  50  which straddle spaced tapered washers  43 ,  43 ′ to position the threaded bore  33  in bridge portion  29  of the locking push abutment  52  in aligned relation with the centering recess  58  in thicker end face  49  of tapered wedge member  44  (shown in phantom in  FIG. 4 ). 
     A locking jacking screw  54  (with rounded tip), in threaded relation through threaded bore  33  in bridge portion  29  of locking push abutment  52 , has a rounded tip  56  that enters corresponding rounded locking centering recess  58 , located in the thicker end face  49  of the tapered wedge member  44  to provide wedging action against the washers  43 ,  43 ′. It is to be understood that rounded tip  56  and corresponding rounded locking centering recess  58  are preferred but not necessary. 
     Conversely, tapered washers  43 ,  43 ′ have shouldered unlocking recesses  51 , to receive and contain threaded unlocking push abutment  53 , that slide longitudinally into the shouldered unlocking recesses  51  which straddle spaced tapered washers  43 ,  43 ′ to position the threaded bore  33  in bridge portion  29  of the unlocking push abutment  53  in aligned relation with the centering recess  58  in thinner end face  48  of tapered wedge member  44  (shown in phantom in  FIG. 4 ). 
     An unlocking jacking screw  54  (with rounded end portion), in threaded relation through threaded bore  33  in bridge portion  29  of unlocking push abutment  53 , has a rounded tip  56  that enters corresponding rounded unlocking centering recess  58 , located in the thinner end face  48  of the tapered wedge member  44  to release or reduce the wedging action against the washers  43 ,  43 ′. It is to be understood that rounded tip  56  and corresponding rounded unlocking centering recess  58  are preferred but not necessary. 
     The pushing embodiments in  FIGS. 4 and 5  have tapered washers  43 ,  43 ′ with washer apertures  15  as in  FIG. 1  and outer faces  47  which are usually normal to the polar axis of stud  10  as shown in  FIG. 1 . Tapered washers  43 ,  43 ′ also have thinner ends  43 B and thicker end  43 A, similar to those shown in  FIGS. 1 ,  2  and  3 , with washer apertures  15  therebetween. Tapered wedge member  44  (with opposing rounded locking and unlocking centering recesses  58 ) has thinner end  44 A and a thicker end  44 B, with elongated wedge aperture  17  therebetween. Opposing faces  45  of wedge member  44  (of second or push embodiment) engage inner faces  46  of tapered washers  43 ,  43 ′ of the second embodiment. 
     In order to ensure clear access for the axial sliding insertion and withdrawal of the abutments  52 ,  53 , without the need to remove or loosen locknut  12 , the tapered washers  43 ,  43 ′ may be sized to extend radially outwardly beyond the locknut  12 . 
     Locking and unlocking jacking Screws  54  have heads  55  which comprise any prior art means for rotating jacking screws  54 , as do heads  20 ,  30  of  FIG. 1 . A hexagon recess in head  55  of the jacking screw  54  is readily accessed by an Allen Key in load applying action, or to unload the tapered wedge member when in the reversed location. In some circumstances screwdrivers with various tips may be used with a corresponding head  55 . 
     Head  55  (and heads  20 ,  30 ) may also comprise outer parallel surfaces for rotating the jacking screw with a wrench. Those skilled in the art will recognize these and other appropriate means for rotating jacking screws  54 ,  20 ,  30 . The use of a jacking screw embodiment in lateral pushing relation with the wedge member  44  may enable the use of a thinner tapered wedge member  44 , and may be more rapidly assembled and disengaged in relation to the threaded stud  10  (not shown). 
     Referring to  FIG. 6 , this shows a portion of a tension load applying device  60 , powered by the load shaft  62  of a hydraulic cylinder (not shown). The load shaft  62  is attached by way of a threaded first stud  64  (shown in phantom) to a load cell  66 . A second threaded stud  68  (also shown in phantom) connects the load cell  66  to a set of gripping jaws  70 . Mounted upon the stud  64  and interposed between the load shaft  62  and the load cell  66  is a first locking wedge system  13 , as previously described. Mounted upon the stud  68  and interposed between the load cell  66  and the gripping jaws  70  is a second locking wedge system  13 , as previously described. The threaded elements of  FIG. 6  are assembled by hand, and screwed together, hand tight, so as not to apply any significant torque to the load cell. The respective locking wedge systems  13  are then adjusted, as described above, to apply a compressive reaction load to the adjoining components  62 ,  66 , and  70 , while correspondingly tensioning the studs  64  and  68 . The tension load applied against the studs  64  and  68  is in excess of the planned tension loading to be applied by the load shaft  62  (and recorded by the load cell  66 ), so that the locked condition of the locking wedge systems  13  and the load applying device  60  will be maintained at all times during operation of the device  60 . 
     Referring to  FIG. 7 , a load shaft  62  of a hydraulic cylinder (not shown) is secured to the shaft  72  of a pivoted anchor  74  that is bolted to a test specimen  76 . As in the case of the  FIG. 6  embodiment, the shafts  62  and  72  are connected by way of a threaded stud  78  (shown in phantom), with a locking wedge system  13  in accordance with the invention interposed between the shafts  62  and  72 . The threaded elements, with the locking wedge system  13  inserted in position, are screwed together until hand-tight, and the locking wedge system  13  is then adjusted so as to apply the desired level of tension to the stud  78 . As in the case of the  FIG. 6  components, the tension load applied against the stud  78  is in excess of the planned tension loading to be applied by the load shaft  62  so that the locked condition of the locking wedge system  13  and the load applying device  62  will be maintained at all times during its operation. 
     In this specification the term locking jacking screw means a threaded screw used to axially loan the stud, and the term unlocking jacking screw means a threaded screw used to axially unload the stud. In the embodiments disclosed in  FIGS. 1 to 3  locking jacking screw and unlocking jacking screw are identical (although they need not be) but are described separately in the detailed description for clarity. In the claims the term threaded screw means a locking jacking screw, an unlocking jacking screw or a locking and unlocking jacking screw as context requires. In the case where one of the first wedge angle and the second wedge angle is zero degrees then the end of the washer axially opposite the thinner end of the tapered washer shall also be considered the thinner end and the laterally opposite end shall be considered the thicker end, and the washer with the zero degree taper shall nonetheless be deemed a tapered washer in the claims. 
     Other embodiments incorporating the principles of the present invention will be recognized by those skilled in the art. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 Parts List 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 10 
                 threaded stud 
               
               
                 12 
                 lock nut 
               
               
                 12′  
                 inner face of nut 
               
               
                 13 
                 locking wedge system 
               
               
                 14, 14′ 
                 tapered washers 
               
               
                 14A 
                 thicker ends (of tapered washers) 
               
               
                 14B 
                 thinner ends (of tapered washers) 
               
               
                 15 
                 washer aperture (of tapered washers) 
               
               
                 16 
                 tapered wedge member (for pulling) 
               
               
                 16A 
                 thinner end (of tapered wedge member) 
               
               
                 16B 
                 thicker end (of tapered wedge member) 
               
               
                 17 
                 wedge aperture (of tapered wedge member) 
               
               
                 18 
                 locking jacking screw 
               
               
                 20 
                 locking jacking screw head 
               
               
                 22 
                 threaded locking aperture (of tapered wedge member) 
               
               
                 22′ 
                 threaded unlocking aperture (of tapered wedge member) 
               
               
                 24 
                 locking pull abutment 
               
               
                 24′ 
                 outer surface of locking pull abutment 
               
               
                 25 
                 locking recesses 
               
               
                 26 
                 unlocking pull abutment 
               
               
                 26&#39;  
                 outer surface of unlocking pull abutment 
               
               
                 27 
                 unlocking recesses 
               
               
                 28 
                 foot portions (of abutment) 
               
               
                 29 
                 bridge portion (of abutment) 
               
               
                 30 
                 unlocking jacking screw 
               
               
                 31 
                 clearance bore (in bridge of pull abutment) 
               
               
                 32 
                 unlocking jacking screw head 
               
               
                 33 
                 threaded bore (in bridge of push abutment) 
               
               
                 40 
                 opposing tapered faces (of tapered wedge member) 
               
               
                 41 
                 inner faces of tapered washers 
               
               
                 42 
                 outer faces of tapered washers 
               
               
                 43, 43′ 
                 tapered washers (of second embodiment) 
               
               
                 43A 
                 thicker end of tapered washers (with shouldered recesses) 
               
               
                 43B  
                 thinner end of tapered washer (with shouldered recesses) 
               
               
                 44 
                 tapered wedge member with opposing centering recesses  
               
               
                   
                 (for pushing) 
               
               
                 44A 
                 thinner end (of tapered wedge member with centering recesses) 
               
               
                 44B 
                 thicker end (of tapered wedge member with centering recesses) 
               
               
                 45 
                 opposing faces of tapered wedge member (of second embodiment) 
               
               
                 46 
                 inner faces of tapered washers (of second embodiment) 
               
               
                 47 
                 outer faces of tapered washers (of second embodiment) 
               
               
                 48 
                 thinner end face (of tapered wedge member) 
               
               
                 49 
                 thicker end face (of tapered wedge member) 
               
               
                 50 
                 shouldered locking recesses 
               
               
                 51 
                 shouldered unlocking recesses 
               
               
                 52 
                 locking push abutment 
               
               
                 53 
                 unlocking push abutment 
               
               
                 54 
                 jacking screw with rounded tip 
               
               
                 55 
                 head of jacking screw with rounded tip 
               
               
                 56 
                 rounded tip (of jacking screw of second embodiment) 
               
               
                 58 
                 centering recesses (in tapered wedge member of second  
               
               
                   
                 embodiment) 
               
               
                 60 
                 tension load applying device 
               
               
                 62 
                 load shaft 
               
               
                 64 
                 first threaded stud (shown in phantom) 
               
               
                 66 
                 load cell 
               
               
                 68 
                 second threaded stud (in phantom) 
               
               
                 70 
                 gripping jaws 
               
               
                 72 
                 shaft (of pivoted anchor) 
               
               
                 74 
                 pivoted anchor 
               
               
                 76 
                 test specimen 
               
               
                 78 
                 threaded stud 
               
               
                 W 
                 threaded workpiece 
               
               
                 W′ 
                 inner face of threaded workpiece 
               
               
                 T 
                 angle of taper