In-line strainer with tension control mechanisms for use on high tensile wire

Abstract

An in-line strainer for placement within a span of wire fence to apply tension thereto is provided. The in-line strainer includes a reel having a hollow central hub for receiving a torque limiting mechanism. The torque limiting mechanism includes a central axle and a spring mechanism. As the axle is manually rotated, the reel is also rotated through its engagement with the torque limiting mechanism until a target tension on the wire is reached. Once the target tension has been reached, the torque limiting mechanism disengages, allowing the axle to “slip” relative to the reel, preventing further rotation of the reel and, consequently, further tensioning of the wire. In addition, the in-line strainer includes a failure mechanism which ensures that, when the load threshold on the fence is exceeded, the in-line strainer will automatically release tension on the wire wound thereon in a predictable and safe manner.

1 . An in-line strainer for tensioning wire fencing comprising:
 a body rotatably supporting a reel onto which fence wire is wound to tension said fence wire, said reel having a plurality of alternating external teeth and notches;   a pawl pivotally mounted to said body for engaging said notches on said reel to prevent said reel from unwinding as said fence wire is tensioned; and   a torque limiting mechanism engaged with said reel and configured to rotate said reel up to a threshold wire tension, said torque limiting mechanism disengaging from said reel when said threshold wire tension is reached so that further winding rotation of said reel is prevented.   
     
     
         2 . The in-line strainer as set forth in  claim 1 , wherein said reel has a hollow center portion and said torque limiting mechanism includes an axle and a spring mechanism received within said hollow center portion, rotation of said axle concurrently rotating said reel through engagement of said spring mechanism with said reel center portion until rotational force required to rotate said axle exceeds a resistance provided by said engagement. 
     
     
         3 . The in-line strainer as set forth in  claim 2 , wherein said torque limiting mechanism further includes a detent positioned between said spring mechanism and an inner wall of said hollow center portion, said inner wall including at least one notch into which said detent is received to provide said resistance while said torque limiting mechanism is engaged. 
     
     
         4 . The in-line strainer as set forth in  claim 2 , wherein said axle includes a through-passing channel, said spring mechanism being received within said channel, said torque limiting mechanism further including a pair of detents positioned on either side of said spring mechanism and against an inner wall of said hollow center portion, said inner wall including at least two opposed notches into which said detents are received to provide said resistance while said torque limiting mechanism is engaged. 
     
     
         5 . The in-line strainer as set forth in  claim 4 , wherein said inner wall includes a regular alternating pattern of notches and high points regularly spaced around said inner wall, said detents moving from one pair of notches to a next sequential pair of notches upon disengagement of said torque limiting mechanism, said movement creating at least one of tactile and audible feedback to a fence installer tensioning said fence wire each time the detents move to a subsequent pair of notches. 
     
     
         6 . The in-line strainer as set forth in  claim 1 , wherein said in-line strainer further includes a failure mechanism that breaks in a predictable and repeatable manner when said threshold wire tension is exceeded. 
     
     
         7 . The in-line strainer as set forth in  claim 6 , wherein said failure mechanism includes a line of weakness in said pawl, said line of weakness being substantially parallel with an axis of rotation of said reel. 
     
     
         8 . The in-line strainer as set forth in  claim 7 , wherein said line of weakness is formed by a notch in an upper surface or a lower surface of said pawl. 
     
     
         9 . In an in-line strainer for tensioning wire fencing, said in-line strainer having a body rotatably supporting a reel onto which fence wire is wound to tension said fence wire, a reel having a plurality of alternating external teeth and notches, and a pawl pivotally mounted to said body for engaging said notches on said reel to prevent said reel from unwinding as said fence wire is tensioned, the improvement comprising:
 said reel having a hollow center portion; and   a torque limiting mechanism engaged within said hollow center portion and configured so that rotation of said torque limiting mechanism concurrently rotates said reel up to a threshold wire tension, said torque limiting mechanism disengaging from said reel to rotate separately therefrom when said threshold wire tension is reached so that further rotation of said reel is prevented.   
     
     
         10 . The in-line strainer improvement as set forth in  claim 9 , wherein said torque limiting mechanism includes an axle and a spring mechanism received within said hollow center portion, rotation of said axle concurrently rotating said reel through the engagement of said spring mechanism with an inner wall of said center portion until rotational force required to rotate said axle exceeds a resistance provided by said engagement. 
     
     
         11 . The in-line strainer improvement as set forth in  claim 10 , wherein said torque limiting mechanism further includes a detent positioned between said spring mechanism and said inner wall, said inner wall including at least one notch into which said detent is received to provide said resistance while said torque limiting mechanism is engaged. 
     
     
         12 . The in-line strainer improvement as set forth in  claim 10 , wherein said axle includes a through-passing channel, said spring mechanism being received within said channel, said torque limiting mechanism further including a pair of detents positioned on either side of said spring mechanism and against said inner wall, said inner wall including at least two opposed notches into which said detents are received to provide said resistance while said torque limiting mechanism is engaged. 
     
     
         13 . The in-line strainer improvement as set forth in  claim 12 , wherein said inner wall includes a regular alternating pattern of notches and high points regularly spaced around said inner wall, said detents moving from one pair of notches to a next sequential pair of notches upon disengagement of said torque limiting mechanism, said movement creating at least one of tactile and audible feedback to a fence installer tensioning said fence wire each time the detents move to a subsequent pair of notches. 
     
     
         14 . The in-line strainer improvement as set forth in  claim 9 , wherein said in-line strainer further includes a failure mechanism that breaks in a predictable and repeatable manner when said threshold wire tension is exceeded. 
     
     
         15 . The in-line strainer as set forth in  claim 14 , wherein said failure mechanism includes a line of weakness in said pawl, said line of weakness being substantially parallel with an axis of rotation of said reel. 
     
     
         16 . The in-line strainer as set forth in  claim 15 , wherein said line of weakness is formed by a notch in an upper surface or a lower surface of said pawl. 
     
     
         17 . An in-line strainer for controlling tension on wire fencing comprising:
 a body rotatably supporting a reel onto which fence wire is wound to tension said fence wire, said reel having a plurality of alternating external teeth and notches;   a pawl pivotally mounted to said body for engaging said notches on said reel to prevent said reel from unwinding as said fence wire is tensioned; and   a failure mechanism associated with said pawl that releases tension on the fence wire in a predictable and repeatable manner when a predetermined threshold wire tension is exceeded.   
     
     
         18 . The in-line strainer as set forth in  claim 17 , wherein said failure mechanism includes a line of weakness in said pawl along which the pawl breaks when the predetermined threshold wire tension is exceeded, said line of weakness being substantially parallel with an axis of rotation of said reel. 
     
     
         19 . The in-line strainer as set forth in  claim 18 , wherein said line of weakness is formed by a notch in an upper surface or a lower surface of said pawl. 
     
     
         20 . The in-line strainer as set forth in  claim 17 , further comprising a torque limiting mechanism engaged with said reel and configured to rotate said reel up to said threshold wire tension, said torque limiting mechanism disengaging from said reel when said threshold wire tension is reached so that further winding rotation of said reel is prevented.