Advantage to six wheel drive?

[Joe G.]

Live axles vs. Dead axles is more a matter of personal choice. There are definite pros and cons to both, and great teams have used both.

Live axles are generally easier to work with. With a hex shaft system, wheels and other components can be switched out extremely quickly, and independently, so you don't have to remove a sprocket to change the wheel. They are generally easier to build in a cantilevered setup. Live axles can be built inside of structural members, and transfer torque, allowing sprockets to be mounted further away from the wheels. This also makes live axles suitable for direct drive. Live axles also make the attachment of encoders easy.

Dead axles are less expensive and time consuming to build initially, since you don't have to broach parts, buy hubs, or deal with keyways. Axles often take the simple form of shoulder screws, further reducing their price. Dead axles can also be squeezed into tight places, since they don't need bearings at the interface between axle and structure. In fact, dead axles can double as standoffs, and serve key structural roles! See the Revolution swerve module for an example of this. Finally, some argue that dead axles allow faster acceleration, since the motor does not have to spin the mass of the axle.