One of my earliest jobs after high school was at a cement company. The fella I replaced was basically crushed under a front axle after a jack failed with no stands! He was found alive (barely) as he was able to get the smallest of gasping breaths for an unknown amount of hours. He couldn't even scream or yell! That image made an impression on me to be sure! Can you imagine the front axle of a cement truck across your chest for hours?!?! I never wanted to find out!