a hoistway; and

one or more vertically oriented guide rail lines in the hoistway for guiding vertical movement of one or more movable elevator units; and

one or more movable elevator units mounted in the hoistway vertically movably along one or more guide rail lines, including at least an elevator car; and

a hoisting roping; and

a movable support structure mounted in the hoistway for supporting said one or more movable elevator units below it via said hoisting roping;

a hoisting machine on the movable support structure for moving the hoisting roping, for thereby moving said one or more movable elevator units; and

wherein said movable support structure is configured to move independently of the elevator car and comprises a body portion, a shelf structure projecting laterally from the body portion, and at least one auxiliary suspender engaged with the shelf structure and a part of the movable support structure, which part is located higher than the shelf structure, and the hoisting machine is mounted on the shelf structure.