Worm 3 rotates about fixed axis A and meshes with spherical half-nut 4 which is seated in spherical recess a of pitman arm shaft 2. When worm 3 is turned, half-nut 4 is displaced in a direction parallel to the worm axis, turning shaft 2, which controls the front wheels of the automobile, about fixed axis B-B. Half-nut 4 is held constantly in engagement with worm 3 by spring 5 whose tension is adjusted by screw 6. Shaft 2, mounted in housing 1 as in a bearing, can turn about a vertical axis.
$2838$WG,FD$