A.
What's Your Angle? What is camber? Camber is what makes the wheels go 'round.
It is the angle made by the wheels of a wheelchair (or automobile) with the "vertical" and can be positive or negative camber.
The vertical is an imaginary line perpendicular to the axle.
If the bottom of the wheel is farther out than the top of the wheel (away from the vertical), it is called negative camber, measured in degrees.
With negative camber, the top and rim of the wheel is closer to the user's arms, an advantage in wheelchair sports, racing, turning and other acrobatics.
With this arrangement, one of the many advantages is that it provides better lateral (sideways) stability, both static and kinetic, also known as angling.
The camber angle alters the handling qualities of the wheelchair suspension by improving the grip when cornering.
This is because it places the tire at a more optimal angle to the road by transmitting forces.
If the tire had zero camber, the inside edge of the contact point would begin to lift off the ground, reducing the area of contact.
By applying negative camber, this effect is reduced, maximizing the point of contact.
This is only true for the outside tire during a turn.
The inside tire would benefit most from positive camber.
Conversely, for maximum straight-line acceleration, the greatest traction is attained when the camber angle is zero (the tread is flat on the road).
What was once an "art" in design has now become a more exact and scientific technique through the use of computers.
All variables involved can be mathematically optimized and as a result, the handling of wheelchairs has been dramatically improved in recent years.
B.
Symptoms and Causes Excessive camber angle can lead to increased tire wear and impaired handling.
As the camber angle increases, the distance between wheels (measured at the bottom to the wheels, at ground-level) increases.
If too much camber is added, there may be a problem getting through doorways.
The amount of camber required for ordinary, daily use is not the same as that that is required for wheelchair sports.
Some more expensive models of wheelchairs have methods of adjusting the camber dependent upon action and sport desired.
Besides the greater stability of cambered wheelchairs, cambered rear-wheels provide an easier reach to the hand-rims on the wheels making the entire hand-propulsion system less strenuous.
A study on wheelchair characteristics during the 1980 Paralympics showed a trend of increased success of the athlete and his chair that had increased camber.
Off-road vehicles such as agricultural tractors generally use positive camber.
In such vehicles, the positive camber-angle helps to achieve a lower steering effort.
Also, some single-engine aircraft that are primarily meant to operate from unimproved surfaces such as bush-planes and crop-dusters have their main wheels equipped with positive-cambered wheels to better handle the deflection of the landing gear as the aircraft settles on rough, unpaved and unimproved airstrips.
C.
Want To Be A Sport (In a Wheelchair) - Then Angle-Up! With increased camber, the ride is softer, lateral stability is increased, the footprint is wider and the manual propulsion system is a bit easier to move with less strain on the shoulders.
Further, the user's hands are better protected in tight areas since the bottom of the wheels will make contact with walls and door-frames first, before contact is made by any part of the rest of the body.
Camber makes the wheelchair turn quicker, gives it a "sportier" look, the push-rims are in a more positive position for pushing with traction being diminished (due to the angling of the tread) and wear on the tires becomes slightly uneven by comparison to conventional tires.
A conventional tire has treads placed in the center of the tire.
Cambered tires ride on the inside edges of the tire.
To compensate for cambering, some manufacturers make their tires with offset-treads.
D.
Cautions and Summary Be advised, once again, that cambering is for sport(s), only, allowing wheelchair-bound participants to perform unusual motions, movements and maneuvers (out-of-the-ordinary) and not mundane.
It is not for the average wheelchair user.
It is a fantastic feature when used in the proper setting.
To be a "sport" and participate in wheelchair sports, cambering is not only necessary but is an essential in almost every wheelchair sport.
Viel Glück (German - "Good Luck").