Answer:
What goes around the wood but never goes into the wood?
My days are numbered.
I help engines spin and pants stay up.
I am black of eye and bright of hair. I fast into the ground and follow my lord as he races around the world. What am I?
I can fly but I have no wings. I can cry but I have no eyes. Wherever I go darkness follows me.
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.