Manual Wheelchairs - World Health Organization

48 I guIdelInes on the provIsIon of manual wheelchaIrs In less resourced settIngs
Forward stability is affected by the size and position of the front castor wheel in relation to the
user’s centre of gravity. Ways of increasing forward stability and their associated advantages and
disadvantages are shown in Table 2.4.
Table 2.4. Aim: to increase forward stability
Advantages Disadvantages
By moving the front castor wheel forward of the user’s centre of gravity
n The wheelchair will resist tipping forward when the
castors are stopped suddenly by an object they cannot
roll over.
n less weight on the front wheels will reduce the rolling
resistance of the front wheels, allowing the wheelchair
to roll more easily.
n Front castor size significantly affects dynamic stability;
with larger front wheels the wheelchair will be able to
roll over larger obstacles without being stopped and
tipped forward.
By using larger front castor wheels
Note: If the footrests are ahead of the front wheels, a weight placed on the footrests (a heavy child, for example) can tip the wheelchair forwards..
n Overall wheelchair length is longer, making it harder to
manoeuvre in confined spaces.
n larger front castor wheels need more room to swivel; the
wheelchair design will need to be much longer or wider
to allow room for the user’s feet.
Sideways stability is affected by wheelchair width. The further out to the side of the wheelchair
the front and rear wheels touch the ground, the more the chair will resist tipping over sideways.
Ways of increasing sideways stability and their associated advantages and disadvantages are shown
in Table 2.5.
Table 2.5. Aim: to increase sideways stability
n Provides more stability.
n Comfortable seating.
n Better for overweight people.
Advantages Disadvantages
By increasing the width of the wheelchair
n Camber brings the wheels closer to the user and more in
line with the user’s forward push stroke, thus making it
easier to push. This can be especially helpful for women,
who usually have narrower shoulders but wider hips
than men.
n Traction is better when traversing slopes.
By adding camber to the wheels (see Fig. 2.4)
n A wide wheelchair is more difficult to get through
narrow doorways.
n not efficient for pushing and hard on upper extremities
because the user has to reach out to push the hand rims.
n A wide wheelchair is more difficult to get through
narrow doorways.
n Camber increases the width of the wheelchair when it is
folded.