Updated with comments/answers from community to make more complete
I'm trying to understand why gears are designed in some specific way instead of another. So far my understanding is that:
- energy is preserved (- some loss due to friction)
- if the speed of rotation is changed
- then the force/torque is inversely & proportionally changed
Criteria I'm aware of are:
- speed: how much to increase/decrease
- force/torque: how much to decrease/increase
- backlash: lost motion due to gap between gear teeth which can cause precision issues
- robustness of gears: strong enough to handle increased torque?
- angle of rotation: eg change 90 with worm gears
- direction of rotation: whether we want input/output rotate in same direction
- wear and tear: due to contact/force applied by gears on each other
- space available: to fit the gears
And some business criteria such as cost & availability of the parts.
-Other than those listed above, are there any other considerations when designing gears?
More specifically, if space,cost,availability weren't concerns, would there be any reason why someone would favor a design with fewer gears (eg A) rather than more (eg B)?
A: 8:1 ratio with 2 gears (64 teeth -> 8 teeth):
B: Same 8:1 ratio with 4 gears (2:1 ratio on the 3 driven gears, taken from here)