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Lever Drive Wheelchairs Mechanical Details.
Figure 1. Single-Lever Cable Drive Wheelchair with cable-caster steering.
Wheelchair steering
system patent.
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© Copyright 2005-2008 Fore-thought Designs™ All Rights Reserved.
"The conventional
hand rim-driven
design has gone
unquestioned for
so long that it has
been practically
immortalized by a
globally
recognized
symbol".
Alternative Steering Concepts
Alternative Caster Steering Actuators
Single-Lever Steering System
Single-Lever, Steerable Drive System

Below is a schematic view of a variable clutch and brake system
concept. It was designed to enable hemi-pelagic wheelchair users to
drive, brake and steer a single-lever wheelchair entirely through the
two drive wheels. It is unlike all other single-lever chairs that must
include a separate mechanical linkage to one caster for steering
control. The variable selection happens inside the tubular lever arm.
The degree of clutch and brake application is controlled by the left /
right tilt position of the hand-grip. The tilt in one direction
simultaneously tensions one caliper brake cable while relaxing the
other. Each brake cable also automatcally relaxes the associated left or
right drive cable as the brake is applied. The muti-speed system can be
powered forward or backward without engaging a reverse switch, and
can turn sharply in place pivoting around a fully stopped wheel.
Arm strength measurement

A simple device was built to measure
average arm strength at various distances
from the shoulder. An ordinary bathroom
scale was sandwiched between the frame
and back support. Repositionable hand- grips
alowed several individuals of varying size
and strength to exert a static force to the
scale for multiple degrees of arm extension.
Force measurements were recorded for each
user allowing a rest intereval between each
position. The results were averaged and
plotted onto a grid comparing force in lbs, to
percent of arm extension. This data was
used to arrange the mechanical drive
components relative to the user for optimal
efficiency. See illustrations below.
"It was designed to
enable hemi-pelagic
wheelchair users to
drive, brake and
steer a single-lever
wheelchair entirely
through the two
drive wheels".
Shifter System
"Its operating
principle resembles
the bow-and-stick
method of making
fire".
Drive Assembly
Push-Pull Cable Steering Concepts
Wheelchair drive
system patent.
Picture links to Steering System Patent.
Picture links to Steering System Patent.
Illustration by Anthony Velleco.
Illustration by
Anthony Velleco.
Anthony Velleco.
Anthony Velleco.
Anthony Velleco.
Lever Drive Wheelchair
receives Honorable Mention
in national contest.

May 2006: The invention was
selected from among over 4,200
submissions by the judges of
the Modern Marvels Invent
Now© Challenge.
See all 100 Honorable Mention
recipients.
www.History.com/invent
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