Patent ID: 7520192

Claim:
A drive screw assembly comprising: a drive shaft having a drive shaft bore defined by an inner surface having a threaded portion, said drive shaft being disposed within a housing having an outer opening connected to said drive shaft bore, said drive shaft having a longitudinal axis, said drive shaft being free to rotate; a drive screw disposed within said drive shaft bore, said drive screw having a threaded portion, wherein said threaded portion of said drive shaft and said threaded portion of said drive screw are configured to receive one another in a threaded connection and to rotate with respect to one another about said longitudinal axis; a guide collar fixed relative to said housing, said guide collar having a guide bore with an inner support surface, wherein said inner support surface has an inner support surface length, wherein said inner support surface is connected to an outer surface of said guide collar by an inner guide bore opening and an outer guide bore opening; and a screw head affixed to said threaded portion of said drive screw, wherein said screw head is fixed in angular relation to said guide collar, and moveable along a range from a first position to a second position on a range axis that is parallel to said longitudinal axis of said drive screw; wherein said inner support surface of said guide collar supports a supported surface of said screw head or said drive screw in directions normal to said range axis as said screw head moves through said range, wherein said supported surface slides in linear motion relative to said guide collar without substantial rotational motion and without producing substantial frictional losses due to rotational motion as said screw head moves through said range, and wherein said guide collar includes an extension sleeve that is disposed within a portion of said drive shaft bore.