Actually, not much keyframing in this project, as it is inefficient to animatic every parts of the engine each by each. Most of the motion can be controlled by rigging and node graph for linking up all tiny parts.
For example, using node graph to link rotation of two gears.
The main and side gear one are designed to rotate clockwise, while the other one is anti-clockwise.
Other gears are using the same principle as well. Or just simply make it parent to another objects.
Here is another example for showing how I use rigging and node graph, instead of keyframing to do the motion.
With graph editor, motion of this arm should be more “industrial” with stronger force and heavy mechanic feeling. Comparing the two motions as below, I prefer the 2nd version with more dramatic feeling.
Final Motion Design