Were they replaced by the belt system purely out of economics? Are there some other trade offs where belts might be better, other than cost? Did the bevel drives have maintenance or performance issues of their own?
Wel I'm sure economics did factor in - but hopefully it got passed down.
And I'm not expert, but some up-sides to belts vs bevel
- Weight. The belts and rollers will have much mess weight penalty than the bevel drive system
- Mass. The belts and rollers will have much mess mass penalty than the bevel drive system.
- Service. Get a little practice and you can do belts in under 30 min. Getting into a bevel system, in earnest is probably very time consuming.
- Space. The belt system is more compact.