[AleoMagus]

Brakeman is Art
Conductor is John
Engineer is Pete
Fireman is Tom

Art is unrelated
John is Pete's nephew and Tom's son
Pete is Tom's brother and John's uncle
Tom is Pete's brother and John's father

I think this satisfies all the conditions, but I am unsure why it matters that John is older than Art, Perhaps this means I am wrong

Regards
Brad S