Abstract: The present invention provides a solenoid including an electrically conductive coil and a plunger located axially within the coil. The plunger is moved in an axial direction within the coil when the coil is energized. The motion of the plunger in the axial direction in the coil at a position such that, when the plunger is moved to the position by energizing the coil, the force exerted by the plunger is linear with respect to the electric power supplied to the coil.The present invention also provides yarn tensioning apparatus employing a number of yarn tensioning devices using such a solenoid. A control system, including a special device for sensing the tension exerted on the yarn, allows each of the yarn tensioning devices in the apparatus to be individually and automatically controlled. The present invention also provides a method for individually controlling the tension exerted on each yarn either manually or automatically.

Abstract: The present invention provides a solenoid including an electrically conductive coil and a plunger located axially within the coil. The plunger is moved in an axial direction within the coil when the coil is energized. The motion of the plunger in the axial direction in the coil at a position such that, when the plunger is moved to the position by energizing the coil, the force exerted by the plunger is linear with respect to the electric power supplied to the coil.The present invention also provides yarn tensioning apparatus employing a number of yarn tensioning devices using such a solenoid. A control system, including a special device for sensing the tension exerted on the yarn, allows each of the yarn tensioning devices in the apparatus to be individually and automatically controlled. The present invention also provides a method for individually controlling the tension exerted on each yarn either manually or automatically.