This week we met with a professor in the mechanical engineering department and asked him to review our gear hub design. Upon first look, he commented that our design was reminiscent of a manual automotive transmission. Automotive transmissions use a piece called a synchronizer (pictured below) to slide back and forth along an axle and engage different gears. Our design utilizes a similar concept. In our most recent prototype we decided to use 4 knob protrusions instead of the many teeth shown on the synchronizer. We learned this week that the teeth would actually be just as durable as the knobs, and would make the shifting much smoother. 

Our meeting also opened our minds to the possibility of utilizing automotive components in our design. These components are much more common and available than bike parts. In the upcoming week, we are going to evaluate the feasibility of using a dual shaft gear box, similar to a manual car transmission. Our goal in doing this is to reduce the cost of our hub by reducing the number of custom components. Meanwhile, we are continuing to search for and contact potential manufacturers.

In our previous oral report, we discussed the modification of the clutch/gear system to use clutch plates that engage laterally along the face of the gears instead of vertically. We have been woking to incorporate this design into our SolidWorks prototype and run a quantitative torque analysis.

In the meantime we have also begun brainstorming for our next prototype: the 3 gear system that adds a direct 1:1 drive. Our current plan is to use the same prototype as our 2 gear system but to add in a lever that moves the entire input hub closer to the output. This forces both the input hub and the output hub into connection via the ring gear and allows the sun and planetary gears to spin freely. The hub could then be moved back into the reverse drive position and the user will be able to shift between high and low gears as previously explained.