Caster wheels are our dinky, disc-shaped, misunderstood friends that situate themselves at the front of manual wheelchairs. And why are they so misinterpreted, you may ask?
Isn’t a caster just a flippy flappy wheel trying its darndest to steer the wheelchair?
No. In fact, when we cast a close glance at caster wheels, we discover an abundance of cleverly considered biomechanics and feats of engineering. Factors, which can make or break a user’s experience.
Casters spin their way across streets in a variety of sizes, materials, diameters, firmnesses, positions, springinesses, and ease of rotations and swivels. The detailed elements of their genius design could fill an entire book of brain-boggling terminology and concepts. A book that could delve into depths of physics to explore scrub torque, rolling resistance, inertia, propulsion and surface interactions. However for the sake of simplicity, basic facts and features, advantages and disadvantages will be highlighted here. This article will enlighten any individual who seeks to know more about the humble caster.
Wheeling and dealing on the facts and features:
- Size and position of casters greatly affect user stability and centre of gravity, for example:
- There’s decreased chances of tipping forwards if the casters are positioned further in front of the wheelchair, although manoeuvring in confined spaces becomes more difficult.
- There’s increased stability with larger casters as they are more capable to roll over objects without abrupt stopping or tipping. Although, they need more room to swivel and be designed to cater for the user’s feet.
- Manoeuvrability over soft ground is improved with increased contact area of wider and softer casters.
- Wider casters with high tread prevent wheels from sinking in soft ground and make smooth rolling on hard surfaces. Although they will make slow and tight turns more difficult.
Manoeuvring over raised obstacles, curbs or rocks, depends on wheel factors such as:
- The distance of the casters from the user’s centre of gravity,
- The springiness of the casters,
- The amount of castor flutter when hitting bumps at speed,
- The softness and malleability of wheels such as pneumatic tyres, that allow for smooth rolling over bumpy, uneven terrain. They can also provide a cushioned ride and manage door lips easily. However can be punctured, experience more friction, and generate more maintenance.
- And harder urethane or solid rubber tyres are smoother on flat ground and require no maintenance, allowing for easy indoor manoeuvrability and tight turns. However, they provide little shock absorption, and very skilled user technique for efficient outdoor use.
Finally, caster locks are not to be overlooked. They are imperative for providing stability of the casters during transfers. An important consideration is that the user must be able to handle and reach the mechanism independently unless always accompanied by a caregiver.
At Kadia Occupational Therapy, expert prescription of these rounded, ruddy, caster wheel friends of ours is a must-have for our well-rounded OTs. They are skilled in assisting clients to find their ideal match of wheelchair with suitable wheels.
Stay tuned to learn more about the world of Kadia Occupational Therapy. If you are an OT consumer or simply have areas of pending confusion about anything OT related, interventions or assistive devices, do not hesitate to get in contact with us.
From the Kadia Team