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Walter’s Turtle 103

Figure 8.20 Drive wheel with servomotor horn attached.

Figure 8.21 U bracket before mounting of drive servomotor.

The bracket is secured to the base using two 1­in­long 6­32 machine screws,
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four 6­32 nuts, and two 1­in­long 2­lb compression springs, with a � ­in center
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diameter (see Fig. 8.30). The tension and resiliency of the bumper can be
adjusted by tightening or releasing the upper 6­32 machine screw nuts. Once
assembled, the bumper will tilt back and close the bumper switch when the
robot (bumper) encounters (pushes against) an obstacle.