Ancestor Search

My grandfather was Johannas Gotleib Knabe.He was born 6/5/1884 In Castle Shannon, PA just outside Pittsberg.
The only information I have regarding his parents is his mother was Augusta (Bergmen) Knabe and was born in Prussia.She was deaf.They moved to the United States first in 1884 from Aachen, Germany.She was pregnant with my grandfather at the time.The family moved back to Germany for 5 years in 1889 when my Grandfather was 5 years old.They returned to the Pennsylvania area in 1904.My grandfather was a cabin boy on the return ship in 1904 (he was 10 years old).I do not know when, but his father was killed in Germany due to an accident when a horse kicked him in the head.My Grandfather had two siblings that lived beyond infancy.Marie Josephine, and Augusta Knabe Schweizer.Several boys were born before my Grandfather, but none survived.My Grandfather was the only child to have had children.

I am looking for the name of my Great Grandfather, or any other information anyone may have regarding my ancestors.