Because friction plays a large role in the operation of the wedge, it is difficult to determine its mechanical advantage. Let ℓ be the length of the arm, and let p be the pitch of the screw...Because friction plays a large role in the operation of the wedge, it is difficult to determine its mechanical advantage. Let ℓ be the length of the arm, and let p be the pitch of the screw (the distance between successive threads). Then one complete turn of the arm will move the end of the arm a distance 2πℓ, and this will result in the load being moved a distance p. The mechanical advantage of the jackscrew is then FR/FE, or
