Wheelchair Casters
The front wheels of a wheelchair are generally known as the casters because they operate like a caster by spinning horizontally as well as vertically. Casters are available in 3", 5" 6" 7" and 8" x 1" with solid tires and 6" or 8" x 1 1/4" with air tires. On a few models of wheelchairs there is also the option of 8" x 2" air or solid casters. As with the rear wheels, the larger the caster, the easier the chair will roll over rough terrain and the easier it will be to propel and solid tires will roll easier than air tires.
Most people opt for 6" or 8" casters depending on the seat height desired, the footrests desired and the expected terrain where the wheelchair will be used. I usually recommend solid casters as air filled casters often lose air pressure making the wheelchair very difficult to propel by both the user and the caregiver alike.
The 8" x 2" air filled casters are usually standard features of tilt frame wheelchairs because the weight of these chairs is high and rolling over rough terrain is always difficult.
The 3" casters are normally only seen on rigid frame chairs. Because these chairs are performance based, the normal configuration and set up of these chairs allows for the use of these tiny casters. Ideally, rigid chairs should be set up with all of the weight balanced on the rear wheels and the only time the weight of the user and the chair is transmitted through the casters is when the chair is standing still.
Casters usually are constructed with plastic or composite rims however some manufacturers offer aluminum rims for a limited number of sizes. The only time I've ever recommended aluminum casters was for a young adult who was excessively hard on his wheelchair and constantly broke the standard caster rims.
The performance of any wheelchair can be severely affected by improper inflation or set up of the casters. Casters are bolted to a caster fork and at the top of the fork is a part called a caster stem bolt. This stem bolt is inserted into a caster stem bolt housing, which is attached to the frame of the wheelchair, through bearings or bushings and a nut is applied to the top to attach the caster to the chair. It is imperative that this stem bolt housing is vertical at 90 degrees to the floor or the chair will no perform properly. A stem bolt housing which is tilted forward will cause a lot of difficulty for the user to turn the chair or move backward. A stem bolt housing which is titled backward will cause difficulty in moving the chair forward.
