Flipped Falcon Gearbox Feedback

Here is a single speed flipped gearbox I designed to be used with Falcons and 4 inch wheels. It’s geared for a free speed of 14 ft/s with a reduction of 8.05 to 1.

I’m looking for feedback for the gearbox. I’m mostly concerned about the Falcons overhanging the wheel, as well as the distance of the pinions from the motors.


Flipped Gearbox Assembly.STEP (36.8 MB)


Personally, I would be very hesitant using a flipped Falcon gearbox because it puts the delicate, expensive Talon FX (the motor controller portion of the Falcon) and the critical CAN bus very close to the edge of the robot. If you’re being defended and the defender rides up the side of your bumper, you could pretty easily destroy two Falcons and quickly be out $280. Or you can disconnect your CAN bus, so none of your motors will work the rest of the match. For me, the extra few inches of space in the middle of the chassis will almost always make up for the added security.


My plan was for the motors to be completely covered by the bumper rails and bumpers, something similar to the mock-up here.

A defender reaching within frame perimeter is something I was worried about too. I was thinking of making a guard over the top of the motors so that they would be fully covered.


I agree. Perhaps you could extend the back plate for the cluster shaft to provide some bearings or bushings for a bit of spline that extends past the pinions.

Switching the inner and outer gears would also work to move the pinions further down the shaft. It would require spacing the 56 tooth gear further from the tubing but ultimately this would solve your problem without changing much of the original design. Thoughts?

Design instinct is I’d rather cantilever the first pinion at the end of the as-designed output shaft than extend the cantilever of the final drive gear*

*Have not done explicit math or held Falcons in my hands to back this up

I totally concur, as long as that bull gear is only supported on one side; that gear has more torque on it (meaning more lateral force, assuming pressure angles are equal/comparable) than any of the others. Rather than what I suggested above, extending the bearing plate down so it also supported the output shaft and swapping the gears so the pinions are close to the Falcons would probably be even better.

Edit: maybe not a common term outside maritime/naval circles: the bull gear is the gear carrying the greatest torque in a drive train.

I should add that much of this design was based on WCP’s single stage flipped gearbox, where the pinion is also extended past the second stage reduction.

Extending the outer plate down is the perfect solution, I’m just wondering whether it’s necessary since so many teams have run these gearboxes with the pinions extended.

The base diameter of the Falcon spline is 6.062 mm; a CIM shaft is 8mm, so this isn’t apples to apples.

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.