What it does
Focusing on the issue of sit-to-stand for elderly and the disabled, Ez-Lift is an assistive chair that utilises the mechanical advantage of a Ratchet Gear-Pulley system, minimising the stress on the knees and lower backs of elderly during sit-to-stand motion.
Your inspiration
Singapore, like many other developed countries, faces the issue of an ageing population. As Singapore’s population continues to age, with 19.9% of Singapore citizens aged 65 years old and above, we can expect an increased demand for elderly care. One of the most prominent issues faced by the elderly are mobility issues. It is estimated that more than 40% of elderly in Singapore suffer from osteoarthritis, affecting their joints and the tissues around them. These alarming statistics provide sufficient insights for us to narrow down our project scope to tackling elderly’s mobility issues, specifically sit-to-stand issues.
How it works
The Ez-Lift chair is a fully mechanical sit-to-stand assistive device tailored for elderly users with mobility issues. It features a ratchet gear–pulley mechanism housed within custom-fabricated aluminium side frames, which serve as the structural base and mount for all components. Users crank a long-handled lever, turning a ratchet gear via a shaft rod. This coils a high-tensile cable onto a spool, pulling it through a 3-pulley system to lift the seat. The seat pivots about a Grade 5 titanium rod, raising to a 30° incline with minimal effort. The ratchet’s driving and stopping pawls ensure unidirectional motion, while a pawl lifter allows easy reset. With mechanical advantage from the pulley system and lever arm, a 100 kg user only needs ~21 N per hand (i.e. only 2% of user's bodyweight is required as input force for each hand). No electricity is required—prioritising safety, reliability, and affordability.
Design process
The Ez-Lift chair's design process began with identifying the challenge of sit-to-stand transitions among elderly users with joint issues. The team conceptualised a purely mechanical solution—a ratchet gear and pulley system—to lift the seat and reduce strain on knees and the lower back. Early cardboard and acrylic prototypes validated a 30° seat lift, based on ergonomic research. Initially designed as an attachment, the concept was later converted into a full 4-legged standalone chair for broader compatibility and user stability. A ratchet gear system with driving and stopping pawls was developed to control unidirectional motion. A handle with long lever arms transfers torque to a collector spool, coiling a high-tensile cable through a 3-pulley system. This lifted the seat around a Grade 5 titanium rod acting as a fixed pivot, selected for its high yield strength. Pulley placement was optimised using a Python script to minimise cable tension and maximise mechanical advantage. The mechanism was housed within custom aluminium side frames, which supported all moving parts and ensured structural integrity. Pawl guides were added to ensure vertical motion, pawl materials were upgraded from PLA to stainless steel for load durability. Lastly, our pawl lifter enabled easy seat reset.
How it is different
The Ez-Lift chair is a unique, mechanical sit-to-stand solution that uses a custom ratchet gear and pulley system to provide high mechanical advantage. Unlike electric or passive products like the Kadxyan Electric Uplift Cushion or Happy Home Classic chair, it features a manual dual-handle system that lifts the seat up to 30° with minimal effort (i.e. 2% of user bodyweight per hand as input force). This self-powered, low-maintenance design is ideal for homes and care facilities. The handle-pushing action also supports upper-limb rehabilitation, a feature missing in current offerings. Its modular mechanism can be adapted to wheelchairs or hospital beds, extending its utility. With a 150 kg load capacity, lightweight build, and potential for cost-effective scaling, the Ez-Lift chair offers a versatile, mechanical alternative in a market dominated by electric or static systems.
Future plans
For future developments, we are planning to add cushioning to the seat , installing rear wheels to improve portability and offering the chair as both a standalone unit or as an attachment that fits any chair. Lastly, simplifying the assembly process will make the product more user-friendly and accessible for caregivers and end-users alike. Beyond that, our Ratchet Gear - Pulley frames can be an effective force reduction tool in other applications such as hospital beds and heavy load lifting industries. With a low-cost product like Ez-Lift, our chair remains accessible to developing countries and to those that have no access to electricity.
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