Patent Publication Number: US-7707915-B2

Title: Double acting spanner wrench

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   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 
   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 
   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. 
   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. 
   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 
   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. 
   According to an embodiment, an apparatus includes first coupling device ( 12   a ) having a lever end ( 14 ), a gripping end ( 16 ), and an elongated slot ( 30 ); a second coupling device ( 12   b ) having a lever end ( 14 ), a gripping end ( 16 ), and an elongated slot ( 30 ); an axle ( 28 ) disposed within the elongated slot of each coupling device where the coupling devices ( 12   a ,  12   b ) are configured to pivot relative to each other about the axle: a threaded shaft ( 22 ) operatively attached to a bushing ( 24 ) pivotally disposed at the first coupling device lever end ( 14 ) and operatively attached to a threaded seat ( 25 ) pivotally disposed at the second coupling device lever end and configured to advance the lever ends ( 14 ) toward each other as the threaded shaft is rotated in a first direction; and a pair of latches ( 34 ), each latch being rotatably attached to a respective gripping end ( 16 ) of a respective coupling device ( 12   a ,  12   b ), each latch having a distal toe plate configured to engage a circumference of one of a pair of washers ( 18 ), the apparatus being configured to one of tighten or loosen the pair of washers by imparting opposite rotational forces to the washers. 
   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. 
   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. 
   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 
       FIG. 1  is a perspective view of a spanner wrench according to a number of embodiments. 
       FIG. 2  is a top view of a spanner wrench according to other embodiments. 
       FIG. 3  is a side view of the wrench of  FIG. 2 . 
       FIG. 4  illustrates an embodiment of the wrench in operation. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As shown in  FIGS. 1 ,  2 , and  3 , various embodiments of a spanner wrench  10  for loosening or tightening washers are 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 briefly in reference to  FIG. 4 . As shown,  FIG. 1  illustrates an embodiment for loosening washers. As used herein, the term washer includes helical washers, spiral washers, lock nuts, jam nuts, and collars, and in particular washers with ramped or helical opposing faces. The predetermined loads generated between the washer faces may be equal to or greater than the loads encountered on the threaded features of a hydraulic actuator or hydraulic assembly. 
   As shown in  FIG. 2 . the coupling devices  12   a  and  12   b  are assembled such that when the respective gripping ends  16  engage respective washers  18 , a squeezing force applied to the respective lever ends  14  as indicated by arrows C cause the washers  18  to rotate in opposite angular directions (e.g., clockwise and counterclockwise, respectively).  FIG. 2  illustrates an embodiment for loosening washers. Each of the coupling devices  12   a  and  12   b  are preferably machined out of 15-5 stainless steel (SS) and heat treated to a minimum of 220 Kilo-pounds “Kips” Per Square Inch (KSI) minimum tensile strength. 
   In some of the embodiments, the squeezing force applied to the lever ends  14  may be applied by a lever device  20 , also denoted as an upper drawbolt assembly  20 , which is operatively attached to the lever ends  14  of each of the coupling devices  12   a ,  12   b . For example, the lever device  20  may include a threaded shaft  22 , also denoted a high strength drawbolt  22 , that may be operatively engaged with a swivel bushing or thrust shoulder  24  pivotally disposed on the lever end  14  of a first coupling device  12   a  and threaded seat  25  pivotally disposed on the lever end  14  of second coupling device  12   b . The threaded seat  25  has a mating thread to the shaft  22 , while the bushing  24  is not threaded. The shaft  22  may have a nut  26  disposed on one end thereof for engaging with a complementary tool. As the shaft  22  is turned in a clockwise direction as viewed from nut  26  the lever ends  14  of first and second coupling devices are advanced towards each other. The bushing  24  and threaded seat  25  may also be denoted as swivel joints and are preferably made out of manganese bronze, and drawbolt  22  is preferably made out of 15-5 stainless steel and heat treated to 220 KSI. 
   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. 
   As shown in FIGs  1 - 4  the coupling devices  12   a  and  12   b  are operatively and pivotally attached to each other by, for example, an axle  28 , also denoted as a guide pin  28 , disposed in respective slots  30 , also denoted as channels  30 , formed in the devices  12   a  and  12   b . 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. The gripping ends  16  function as the interface between the wrench  10  and the washers  18  as left-hand or right-hand dog latches  34 , also denoted as claws, and where each latch  34  has a distal toe plate  38  that is configured to engage with notches  32  on the circumference of the associated washer  18 . The dog latches  34  are “hook” shaped parts that are preferably made from American Iron and Steel Institute (AISI) 4340 steel and heat treated to a minimum of 250 KSI. The dog latches  34  may swivel freely at the attached pivot point  36  assembled to the associated coupling device  12 . Spherical bearings are a preferred solution to accommodate the helical motion of the washers. In this case, the spherical bearings allow the dog latches  34  to float parallel to the axis of rotation so the wrench is less prone to binding. The dog latches  34  may be attached to pivot point  36  directly or through a second swivel point  40  as a slip joint to accommodate different washer sizes. In many embodiments, the coupling devices  12   a  and  12   b  may be configured such that approximately 45 degrees of rotation about the axle  28  is enabled. 
   With reference to  FIG. 4 , in many applications, each of the washers  18  may include one or more annular notches  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 . As shown.  FIG. 4  illustrates an embodiment for tightening helical or spiral washers because the gripping ends  16  and latches  34  are configured to engage with the washers  18  in a manner to advance them toward each other as they are moved in opposite rotational directions relative to each other. In this embodiment as shown in the two lever ends  14  are forced together by the threaded drawbolt assembly ( 20 ,  24 ,  25 ) resulting in the upper claw rotating the upper washer clockwise as viewed from the top portion of  FIG. 4  and the lower claw rotating the lower washer counterclockwise for tightening. In another embodiment, where the claws are disposed on the opposite washers, when the two lever ends  14  are forced together by the threaded drawbolt assembly ( 20 ,  24 ,  25 ) resulting in the upper claw rotating the upper washer counter clockwise as viewed from the top portion of  FIG. 4  and the lower claw rotating the lower washer clockwise for loosening. The applied motion of rotating the drawbolt  22  pulls the dog latches  34  towards each other in a pinching fashion. As the dog latches  34  are rotated together the washers they are engaged with expand on their opposing helical faces creating an outward force on the washers. The center guide pin  28  is spring loaded to allow the two halves of the wrench  10  to move apart as the wrench is tightened. 
   As shown in the embodiments of  FIGS. 1 and 2 , the dog latches  34  at their respective gripping ends  16  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 . As shown, the first coupling device  12   a  includes an opening so the bushing or thrust shoulder  24  is not captive within the first coupling device  12   a . In this manner, bushing  24  may be detached from engagement with the first coupling device  12   a when the wrench is loosened. 
   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.