Comment by my mechanical engineer brother:
1. Left side animal is propelling the gear for the well gear.
2. The gear is related to the pulley on top of the well which operates the bucket.
3. When the bucket reaches the top, the automatic tilting mechanism pours bucket into a trough into a spigot.
4. Right side animal opens the spigot knob if he wants a drink.
5. Whenever the bucket gets stuck in the well, the right side animal takes the elevator down to fix the problem.
It seems so obvious and logical to me!
Great minds think alike. Apparently.