[philso]

Looking through this forum, you will find many gearbox designs that people have posted over the years. These have had different features and have been the result of many different design decisions. Many of them go through multiple iterations as design flaws are found or the demands on the gearbox change. The one thing that they have in common is that they are all stand-alone gearboxes that can be fully assembled outside the chassis and are attached to a chassis as a sub-assembly. It is not too difficult to swap out a gearbox sub-assembly if the design is found to be inadequate. It would be much more difficult to change the gearbox design if it is an integral part of the chassis.

It is probably only worth considering a gearbox that is integral to the chassis in instances where the manufacturing volume is very high, the target cost must be very low and there is adequate time to build and test multiple iterations of the design. Dr. Joe might be able to confirm this.