Dimitar Stefanov

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Lecture 18

• Dimitar Stefanov

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Wheelchairs and Personal Transportation

• Some history
• Centuries ago transportation of the disabled on
  hammocks slung between poles that were carried by
  others (upper class people)
• Wheelbarrow similar to these for transportation
  of materials
• During the Renaissance first wheelchairs arm
  chairs with wheels placed on them (France)
• Wooden wheelchairs until 1930

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• Franklin D. Roosevelt metal kitchen chairs
  modified with wheels
• Civil War   First record of wheelchairs being
  used in the United States.
• 1907  First patent applied for a folding
  wheelchair with a steel frame.
• 1936  First single cross-brace steel wheelchair
  patented by Everest Jennings Everest (mining
  engineers), Jennings (engineer)
• ErnestJennings first company for wheelchair
  manufacture few years later
• World War II steel-framed wheelchairs with 18
  inch seat width
• 1940s first powered wheelchairs, standard
  manual wheelchairs adapted with automobile
  starter motors and automobile battery
• Rigid power wheelchair frame free space under
  the seat (battery, controller, respirators, etc.)

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• 1948  Removable armrests introduced.
• 1950's  Lightweight chairs developed for sports
  use.
• 1980's-present  New composite frame materials
  developed to further reduce the weight of chairs.
• Personal automobile modified control of the
  standard automobile
• Microcars enlarged powered wheelchairs, speed
  about 10 km/h
• The first voice-activated power wheelchair was
  used in 1984 by a student 
• 1995s omni-directional wheelchairs

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• Categories of wheelchairs
• Manually powered
• Electrically powered

• 200 000 wheelchairs are sold annually within the
  USA
• 20 000 powered wheelchairs

Depot wheelchairs for institutional use,
several people may use one and the same wheelchair
One-arm-drive wheelchairs linkage connection of
the rear wheels
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Indoor and outdoor wheelchairs
Indoor wheelchairs short wheelbases, less
stable in lateral direction

• Wheelchairs, powered by the user
• Wheelchairs, powered by attendants

Ultra light wheelchairs
Sports wheelchairs
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Categories of wheelchairs (continue)
Stand-up wheelchairs
LifeStand, USA, http//www.lifestandusa.com/home.h
tm
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LEVO, Switzerland, http//www.levo.ch/

• Gas spring activated
• Electric activated

Stair-climbing wheelchairs
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Patient transfer systems
Vivax Medical, http//www.vivaxmedicalcorp.com/
Consists of a specially designed electric
(hospital type) bed and wheelchair.       The
Vivax Mobility System has a transfer conveyor
system integrated into the bed frame which moves
the patient from the bed into a specially
designed wheelchair and back again.  A built in
air support system provides true pressure relief
and a low-shear comfortable bed surface.
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Patient transfer systems
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Beach wheelchairs
http//www.beachwheelchair.com/
Scooters
Shoprider, http//www.dcc-shoprider.com/
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Frame design lightweight tubes

• Frame styles
• Box-frame wheelchairs (great strength and
  rigidity)
• Cantilever frame wheelchairs (the frame can act
  as suspension fewer tubes)

Box-frame wheelchair
Cantilever frame wheelchair
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Materials

• Aluminum (6061 aluminum tubing) lightweight,
  high corrosion resistance,
• Steel (chromium- molybdenum alloy) easy to
  welding, wall thickness 0.028 inches, diameter
  0.25-1.25 inches
• Titanium lightweight, strong require special
  tooling, high cost
• Composite materials (carbon fibers) extremely
  strong and tough, lightweight

• Two basic styles of powered wheelchairs on the
  market
• The traditional style, and
• the platform-model powered chair (powered base
  and a chair on it).

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Center of gravity (COG)
Located among the midline of the person and the
chair
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COG location
Seat width as narrow as possible usually 1
inch higher than the users hips
Frame angle
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Wheels and caster
Front casters from 50 to 200 mm in diameter for
manual wheelchairs for daily use.

• Pneumatic casters
• Polyurethane casters

Rear wheels wheels with large diameter
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Caster flutter
Rapid vibration on the front wheels
The caster flutter occurs when there is no enough
trail.