乃變體彈簧之極至，由單扭至變扭乃至各種扭杆之變型得依設計成型。各圈緊密圍繞或分開圈繞，
       俾能適任扭轉負荷(與彈簧軸線成直角)。彈簧之末端可繞成鉤狀或直扭轉臂。
       Well-designed torsion springs will reduce in coil diameter when loading.this reduction
       has to be accounted for if a rod is used through the inside for support.

       必要資料如下(Mandatory data):
       1、控制直徑 (Controlling Diameter)
       a、外徑 (outside Diameter,O.D.)
       b、內徑 (Inside Diameter,I.D. )           
       2、線材尺寸，材料，及等級 (Wire size,material,and class)
       3、有效圈數 (Numbers of active coils)
       4、旋轉方向(左或右旋) Rotating Direction(Left or Right)
       5、自由長度 (Free Length)
       6、荷重 (Loading)
       7、尾端形式 (Type of end )