Brakes. They're probably the most important component on a car or truck. When they're good, everyone is grateful. When they're bad, people can get hurt. This amazing, harrowing dashcam footage was almost the footage of a horrible, preventable crash, but thankfully, the combination of the Volvo semi's brakes and the quick reaction of the truck driver brought the tractor trailer to a dead stop just before it struck an impatient motorist sticking his nose out too far into oncoming traffic. That's some serious luck.