Complex sentence: The whistle operator was known as a whistle punk, who was placed between the men attaching the cables (choker setters), and the donkey puncher, so that he could see the choker setters.
Split into simpler sentences: The whistle operator was known as a whistle punk. It was placed between the men attaching the cables (choker setters), and the donkey puncher, so that he could see the choker setters.