Abstract: An operator for controlling the movement of a window sash relative to a frame with a raised surface along a frame sill thereof, wherein the operator includes a base having a first support surface, an aperture and a bottom exterior surface with a slot therein, the base attached to the frame with the raised surface fitting substantially within the slot. The operator also includes a cover secured to the base and having a second support surface with a hole therethrough defining an internal shoulder, the second support surface mating with the first support surface. A post extends from the cover and through the aperture in the base when the operator is assembled. An arm is pivotally secured to the post and attachable to the sash to control the movement of the sash between open and closed positions. A worm drivably engages the arm and has a worm shaft and a worm shoulder disposed on the worm shaft.

Abstract: An operator for controlling the movement of a window sash relative to a frame with a raised surface along a frame sill thereof, wherein the operator includes a base having a first support surface, an aperture and a bottom exterior surface with a slot therein, the base attached to the frame with the raised surface fitting substantially within the slot. The operator also includes a cover secured to the base and having a second support surface with a hole therethrough defining an internal shoulder, the second support surface mating with the first support surface. A post extends from the cover and through the aperture in the base when the operator is assembled. An arm is pivotally secured to the post and attachable to the sash to control the movement of the sash between open and closed positions. A worm drivably engages the arm and has a worm shaft and a worm shoulder disposed on the worm shaft.