Design and Fabrication of a Low-Power Portable Stairlift for Material Handling Using a Modular Rack-and-Pinion System

Abstract

This project presents the design and development of a lightweight, portable, and low-power mobile stairlift specifically engineered for material handling, addressing a gap not covered by conventional stairlifts designed primarily for human transport. Unlike standard commercial systems that require fixed installation and high-power drives, the proposed stairlift incorporates a compact rack-and-pinion drive with a distributed four-motor configuration that enables stable load carriage on variable residential stair angles. A key innovation of the design is its modular rack system, optimized for portability and rapid deployment on different stair types, enabling use in environments where traditional stairlifts cannot be installed. System development involved conceptual modelling (AutoCAD 3D), structural and drive train design using machine-design principles, material selection, and prototype testing. The four-motor assembly delivered a combined output of 80 W and supported a maximum load of 14.2 kg, with a safe operating load of 5.47 kg (Factor of Safety (FOS) 1.5). Static analysis showed a bending moment of 11.03 N·m and a corresponding bending stress of 71.32 N/mm², within limits for the selected hollow steel frame. The optimized rack system (μ = 0.7) ensured reliable traction, while total power consumption for lifting at 0.5 m/s was only 34.92 W. The results demonstrate a cost-efficient and portable material-handling stairlift with lower power demand and greater deployment flexibility than conventional systems, offering a practical solution for environments where mechanized load transport on stairs is otherwise difficult or unsafe.