[Travis Covington]

Originally Posted by Joe_Widen

How do you guys get those gears to stay put with out keys or set screws? I know you used hex stock on the final stage. I'm mainly asking about the gear on the Fischer Price.

Are you refering to the pinion or the driven gear? The pinion is mounted onto the CIM and AM planetary shafts using the supplied 2mm keyway with an internal spline retaining ring.

The driven gear is also a hex. The only other place we used a keyway within the gearbox was on the output shaft to retain the sprockets that go to the front and back wheels. There is no easy way to put a hex there, as much as I would have liked to.

As for 32 pitch vs 20 pitch, the 32 pitch at 3/8" face was far strong enough for the initial reduction off the motors and allowed for a more compact gearbox overall. The large 32 pitch gear is a 96 tooth, and the large 20 pitch dogged gear has 72 teeth. Both are relatively large, but allowed us to have only one intermediate shaft with no chain reduction.