A stair traversing device comprising a payload body for transporting a payload, a step frame, and a mechanism between the step frame and the payload body to move the step frame relative to the payload body along a cyclical path. The mechanism drives a movement of one of the payload body and the step frame along a first segment of the cyclical path from a retracted configuration to an extended configuration, and drives a movement of the other one of the payload body and the step frame along a second segment of the cyclical path back into the retracted configuration. The payload body and the step frame are configured to remain fixedly in position on a stair when the other one of the payload body and the step frame is moved. The mechanism is configured to maintain the relative orientation between the payload body and the stair.
