Answer:
Brown I am and much admired. Many horses have I tried. Tire a horse and worry a man, tell me this riddle if you can. What am I?
What is it that makes tears without sorrow. And takes its journey to heaven?
I fill a room but take no space.
What two keys cannot open any door?
I save lives on the ground and in the air
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.