This movie was just too darn real for the overclass and so they killed off this movie. THis movie was really about CLASS issues. It exposed the reality of class, so never promoted this movie or gave it what it needed to succeed.
Hoboes roamed the land; riding the rails in a desperate search for jobs. Spurned by society, unwanted and homeless, they became a breed apart. Nomads who scorned the law and enforced their own.
Dedicated to their destruction was The Railroad Man who stood between them and their only source of survival--The Trains.
This is the backdrop for this movie and it is about class war. Now, Robert Aldrich did it in an entertaining way by making it about a duel between two tough guys - the king of the hoboes - A#1 and a brutal train bull - the Shack.
Poor people having an hard time and trying to survive by dodging the hounds of the capital is not class war. Class war is fighting together with your peers for the benefit of your class and, therefore, to your own benefit. It would have been really easy to set a class war story in the years of great depression, since that was an age of collective struggles and violent repression.