Prosthetic Arm Force Reducer Team 1 – Halliday's ... - Ohio University

Figure 7.0.10 Cable Path for Mechanical Advantage System
No modifications were required for the input or output cable. Swage operations, however, were
used to terminate the input cable to the elbow hoop (marked “X” in Figure 7.0.10), and to
terminate the output cable at the pulley eyelet and cable post of the hook.
7.0.10 Testing (Mock-Up)
To test the feasibility and demonstrate the concept of our mechanical advantage design it was
critical to produce a mock-up. This mock-up used a 2 inch I.D. PVC pipe cut to 10 inches to
help simulate the amount of space in a typical
prosthetic forearm. All of the parts were
bought at Lowe’s and the total cost of the
mock-up was just under $28 and took four
hours to manufacture. After completing the
mock up for the mechanical advantage system,
our group then used a fish scale to
approximate the change in input force needed.
The scale was used with the original,
unmodified hook to see what the input force
was, and then this was compared to the input
force using the mechanical advantage. The
overall force value did exactly what was
expected, it was cut in half. The force without
the mechanical advantage was determined to
be approximately 35 lbs, whereas the force
while using the mechanical advantage was
approximately 17 lbs.
Figure 7.0.11 Mock Up
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