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Design Decisions

Decisions to be evaluated: What functions must it perform? What material should be used? What are the overall dimensions? How will it be attached? How can its weight be reduced? How can it be cooled?

Flywheel proe mjd.JPG

Critical Features

The first feature is the circular dish that acts as the base of the flywheel which has a diameter of 5.75". The next important feature is the conical hole in the center of the base that snuggly locates the flywheel to the crankshaft. This has a diameter of .65" at its smallest and .85 inches at its largest. The third critical feature is the fins located along the perimeter. Their purpose is to act as a blower onto the air controlled governor and to create extra surface area for cooling. All of them have an approximate width of .85" and height of 1.25". The overall height and diameter of the part is 2.06" and 5.75" respectively.

Loading Conditions

Attached to the top of the flywheel is the ratchet which is then attached to the pull string of the mower. The force exerted onto the pull string while when the engine is started will create a torque along the central axis of the flywheel. The specific locations of where the force is applied is on the screw holes for the ratchet attachment and on the keyhole for the crankshaft. There will also be some rection forces pushing from the crankshaft in both the vertical and horizontal directions.

Methods of Performance Evaluation

We can use measuring devices to measure the RPM's of the flywheel as a force, close to the amount that is exerted on the pull string, is applied to it to turn the flywheel and the crankshaft. An air velocity meter can be used to measure the velocity of the air pushed by the fins during normal operating conditions, to then calculate how much force it is exerting on the governor. A thermal sensor can then measure the temperature of the fins and the whole flywheel to see how well it is dissipating heat.

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