Patent ID: 7129601

Claim:
An apparatus comprising: a movable member having a magnetically permeable portion contained therein for providing a magnetic flux path therethrough, a first side and an opposing second side, said second side including an outer bearing surface formed thereon; a fixed member for movably supporting the movable member with respect thereto, said fixed member comprising a bearing seat for receiving the outer bearing surface therein and for movably supporting said movable member; a magnetic element fixedly attached to said movable member and movable therewith; a magnetically permeable stator element fixedly attached to said fixed member and positioned within a magnetic flux field of said magnetic element such that an air gap is formed therebetween, thereby providing a magnetic traction force acting across the air gap for urging the moving element toward the fixed element; and, at least one stator current coil wound onto a portion of the stator element for inducing an electromagnetic force within the stator element in response to,a current passing therethrough, said electromagnetic force acting on the magnetic element; wherein the bearing surface of the movable member and the bearing seat of the fixed member have a coefficient of friction and wherein said magnetic tractive force in combination with the coefficient of friction provides a clamping force for urging the bearing surface into contact with the bearing seat with sufficient force magnitude that the clamping force holds the movable member in a stationary orientation with respect to the fixed member during normal operation of the apparatus.