Complex sentence: With Emma's help, he manages to activate his monowheel as more agents, operating a large steam automotive, give chase, succeeding in thwarting it on a railroad track by putting it in the way of an incoming train.
Split into simpler sentences: With Emma's help, he manages to activate his monowheel as more agents, operating a large "steam automotive", give chase. He succeeds in thwarting it on a railroad track by putting it in the way of an incoming train.