Complex sentence: The impact of flat wheels on the rail causes a hammering action that produces higher dynamic forces than a simple passage of a round wheel; these forces can exacerbate a weak rail condition and cause a rail break.
Split into simpler sentences: The impact of flat wheels on the rail causes a hammering action that produces higher dynamic forces than a simple passage of a round wheel. These dynamic forces can exacerbate a weak rail condition and cause a rail break.