Abstract:
A wrench with the property of applying two opposing forces to a pair of spiral washers. The basic design for the wrench can be used to tighten or loosen the pair of spiral washers in a controlled, repeatable manner.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 60/905,675 filed on 7 Mar. 2007 by Robert D. Fordice entitled “Helical Preload Washer Double Acting Spanner Wrench,” the contents of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The embodiments described herein generally relate to tools and more specifically relates to tools that provide tightening or loosening forces to a pair of lock nuts or lock washers. 
       BACKGROUND 
       [0003]    Helical or spiral washers are commonly used in pairs to preload threaded fittings on hydraulic actuators. Each washer has a flat surface, a helical surface, and notches along the outer circumference. The helical faces of the washers allow a preload force to be imparted on the threaded components with which they are assembled. Typically, two washers are installed with their helical faces opposing each other. As the washers are rotated in opposite directions against each other, the outer flat surfaces generate a preload force that prevents backlash during through-zero cyclic loading. This preload must be greater than the load generated by the actuator during test cycles to prevent backlash in the load linkage. 
         [0004]    Tightening and loosening spiral washers can be labor intensive and time consuming on tests that use many hydraulic actuators. Specially designed spanner wrenches, one per spiral washer, are typically recommended for tightening or loosening the washers. Often the task has been accomplished using impact devices on the spanner wrenches, often resulting in damage to the washer and or the wrench. Such methods do not allow regulation of the amount of preload force applied to the threaded fasteners by the washers. 
         [0005]    Although other techniques exist, all prove ineffective on the shop floor due to the magnitude of the forces required, the lack of a method to apply forces simultaneously to each washer, and the lack of a good way to hold one washer “still” while applying wrench forces on the other. 
       SUMMARY 
       [0006]    In accordance with the disclosure, the problem of applying controllable, measurable forces to a pair of spiral washers is solved by an apparatus which imparts equal but opposite circumferential forces on two washers simultaneously. The circumferential forces are a function of a single input force or pressure controlled by an operator. 
         [0007]    One embodiment of such an apparatus is a double-acting spanner wrench. The wrench engages the washers via hooking onto slots in the washers, and effectively pulls each washer in opposite circumferential directions with respect to the other. The hooks pull towards each other as the lever ends of the wrench are drawn together by a threaded draw bolt as it is rotated by an operator with a socket or ratchet wrench. The pivot mechanism for the wrench is such that the gripping ends move with the washers and also allows the wrench to accommodate a number of different washer sizes. 
         [0008]    The task of preloading threaded rod and cylinder ends can now be accomplished with one tool. The load factor can be precisely controlled with simple dial marks on the washers for visual reference; alternatively washer force can be controlled by using a torque wrench on the draw bolt. The fatigue factor and risk to technicians is greatly reduced by using the present invention over alternative means. 
         [0009]    One of the advantages of the wrench is that it is easy to use and can simultaneously tighten or loosen two lock washers with respect to each other. Another advantage is that the wrench can be used to apply a measurable and repeatable torque to two spiral washers which, in turn, results a measurable and repeatable preload force. 
         [0010]    Various embodiments of the wrench can be used to tighten or loosen helical lock washers, lock nuts, jam nuts, and collars which would otherwise require the use of two wrenches. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a spanner wrench according to a number of embodiments. 
           [0012]      FIG. 2  is a top view of a spanner wrench according to other embodiments. 
           [0013]      FIG. 3  is a side view of the wrench of  FIG. 2 . 
           [0014]      FIG. 4  illustrates the wrench in operation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    As shown in  FIGS. 1 ,  2 , and  3 , a spanner wrench  10  for spiral washers is configured to impart opposite rotational forces to the washers, with the opposite rotational forces being a function of a single applied force. According to a number of embodiments, the wrench  10  may include a pair of coupling devices  12   a  and  12   b  each including a lever end  14  and a gripping end  16 . The gripping ends  16  are adapted to engage a respective one of the washers  18 , such as shown in  FIG. 4 . 
         [0016]    As shown in  FIG. 2 , the coupling devices  12  are assembled such that when the gripping ends  16  engage washers  18 , a squeezing force applied to the lever ends  14  as indicated by arrows C cause the washers  18  to rotate in opposite angular directions (e.g., clockwise and counterclockwise, respectively), thus applying a preload force. 
         [0017]    In some of the embodiments, the squeezing force applied to the lever end  14  may be applied by a lever device  20  which is operatively attached to the lever ends  14  of each of the coupling devices  12 . For example, the lever device  20  may include a threaded shaft  22  operatively engaged with threaded seats  24  pivotally disposed on the lever ends  14 . The shaft  22  may have a nut  26  disposed on one end thereof for engaging with a complementary tool. 
         [0018]    Accordingly, when the threaded shaft  22  is rotated clockwise, the lever ends  14  are drawn inwardly or toward each other, thereby tightening the wrench&#39;s grip on the washers  18  and rotating the washers  18  respectively engaged therewith in opposite rotational directions. And when the threaded shaft  22  is rotated counterclockwise, the lever ends  14  are urged outwardly or away from each other, thereby loosening the wrench&#39;s grip on the washers. 
         [0019]    As shown in  FIG. 1 , the coupling devices  12  are operatively and pivotally attached to each other by, for example, an axle  28  disposed in respective slots  30  formed in the devices  12 . Accordingly, when the shaft  22  is actuated, the lever ends  14  and the gripping ends  16  rotate about the axle  28 , while the slots  30  allow translation of the axle  28  therein. In many embodiments, the coupling devices  12  may be configured such that approximately 45 degrees of rotation about the axle  28  is enabled. 
         [0020]    With reference to  FIG. 4 , in many applications, each of the washers  18  may include one or more annular notch  32 . In such embodiments, the gripping end  16  of each of the coupling devices  12  may include a latch  34  configured to engage with the notches  32  of a respective one of the washers  18 . 
         [0021]    As shown in the embodiments of  FIGS. 1 and 2 , the latches  34  may be pivotally attached by respective axles  36 . In addition, the latches may include a distal toe plate  38  configured to engage with the notches  32 . As shown in the embodiment of  FIG. 1 , the toe plates  38  may be pivotally attached by respective axles  40 . 
         [0022]    While embodiments have been presented in the foregoing detailed description, it should be appreciated that a number of variations exist and applications exist. It should also be appreciated that the described embodiments are only examples and are not intended to limit the scope, applicability, or configuration of the described embodiments in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope as set forth in the appended claims and the legal equivalents thereof.