Abstract: A lift drive comprising: a spiral drive element having an axis of rotation, a rack having teeth sized and shaped to be engaged by the spiral drive element, the rack having a longitudinal axis parallel to the axis of rotation, and a motor to rotate the spiral drive element, wherein upon the spiral drive element-rotating, one of the spiral drive element and the rack moves relative to the other along the longitudinal axis.

Abstract: A stair lift for lifting and lowering at least one person on a rail on a stairway. There is a carriage mountable to the rail, the carriage having a track engaging drive, and a motor to power the drive, the powered drive causing the carriage to move along the rail. There is a central support post mounted on the carriage and an offset arm connected to the seat support post. The offset arm is mounted to the carriage in one of a left side or a right side position. A seat is mounted on the offset arm, and a notched plate secures the seat in position on the offset arm in either the left side or right side position and permits the seat to swivel between a sideways facing position and an upward facing position to facilitate the person getting into and out of the seat.

Abstract: A lift drive comprising: a spiral drive element having an axis of rotation, a rack having teeth sized and shaped to be engaged by the spiral drive element, the rack having a longitudinal axis parallel to the axis of rotation, and a motor to rotate the spiral drive element, wherein upon the spiral drive element-rotating, one of the spiral drive element and the rack moves relative to the other along the longitudinal axis.