Multi-Functional Ski Chair for Disabled Persons with Rack-and-Pinion Steering

The problem

Many individuals with lower-limb disabilities find traditional sit-skis difficult to operate because they require precise edge control or significant upper-body strength to steer. Maintaining balance while navigating slopes is challenging, especially when turning quickly or encountering bumps. Existing solutions often lack integrated safety features that prevent tipping over if the user loses control, leading to potential falls or injuries. Additionally, standard frames transmit vibrations directly to the rider, causing discomfort during prolonged use on rough terrain. There is a need for a device that allows intuitive steering through natural body movements while providing automatic stabilization and effective shock absorption.

The solution

The patented ski chair addresses these issues through a mechanical linkage system that converts torso movement into directional changes.

1. Seat and Base Assembly: A seat (1) is mounted on a support rod (8), which connects to a support plate (7). Below this plate sits a snowboard (10).
2. Steering Mechanism: The back of the seat contains a rectangular groove (2) housing a C-shaped plate (3). This plate has a soft pad for comfort and carries a rack (4). The rack meshes with a gear (5) fixed to the seat’s back.
3. Motion Translation: When the user leans left or right, the C-shaped plate moves laterally, driving the rack. The rack rotates the gear (5). Two pull rods (6), which are spring telescopic rods, are hinged to opposite sides of the gear. As the gear turns, one rod extends and the other retracts, tilting the support plate (7) and the attached snowboard (10).
4. Anti-Tip System: If the user leans excessively, the C-shaped plate presses against pressure plates (13) inside the groove. These plates compress first springs (12) and pull wire ropes (15) connected to ejector pins (22). The pins release locking inserts (20) from holes in inclined support plates (17). Torsion springs then push these inclined plates outward, deploying small auxiliary skids or stabilizers to prevent the main chair from rolling over.
5. Shock Absorption: The support rod (8) and the connection between the support plate (7) and snowboard (10) utilize additional spring telescopic rods (9 and 11). These allow vertical and longitudinal flexing, absorbing impacts from jumps or uneven surfaces.

Who it is for

• Adaptive Sports Equipment Manufacturers: Brands looking to expand their line of sit-skis for users with spinal cord injuries or amputations who need simplified controls.
• Rehabilitation Centers and Therapists: Facilities offering winter sports therapy programs where ease of operation and safety are critical for patients learning to ski.
• Outdoor Recreation Retailers: Shops specializing in accessible outdoor gear that cater to customers seeking independent mobility on slopes without assistance.
• Design Studios for Assistive Devices: Engineers developing ergonomic interfaces that rely on residual body movement rather than manual dexterity or strength.

How it works

The main parts

Operating steps

1. User Leans: The rider shifts their torso left or right against the C-shaped backrest (3).
2. Rack Moves: The lateral movement drives the rack (4), which rotates the gear (5).
3. Base Tilts: The rotation pulls one telescopic rod (6) in and pushes the other out, tilting the support plate (7) and snowboard (10).
4. Direction Changes: The angled snowboard carves a turn on the slope.
5. Stabilization: If the lean exceeds a threshold, the pressure plates (13) activate the anti-tip struts (17) to widen the footprint and prevent rollover.

Applications

Recreational Slope Skiing

Users with lower-limb disabilities can navigate groomed trails independently. The torso-based steering eliminates the need for hand controls, allowing riders to focus on balance and speed management using natural body posture.

Adaptive Training Programs

Rehabilitation centers can introduce skiing as part of physical therapy. The automatic anti-tip feature provides a safety net for beginners who may struggle with edge control, reducing the fear of falling and encouraging participation.

Off-Piste Exploration

The spring-loaded suspension system absorbs shocks from uneven terrain. This makes the chair suitable for exploring less-groomed areas where bumps and dips are common, enhancing comfort and control for experienced adaptive athletes.

Family Ski Outings

Independent operation means users do not require a guide or assistive staff member to steer. This facilitates social inclusion, allowing disabled skiers to participate in group activities at their own pace alongside friends and family.

Where it is less suitable

• High-Speed Racing: The mechanical linkage may have lag compared to direct-edge binding systems used in competitive sit-ski racing.
• Extreme Terrain: While it has shock absorption, it is not designed for steep cliff drops or technical freestyle maneuvers requiring rapid weight shifting.
• Users Without Torso Control: Individuals who cannot actively lean their upper body will not be able to steer the chair effectively.