Before anything else is discussed, it’s important that the knowledge about the mechanics of a seat belt is outlined. The best way to do this is to lead you through a mental meditation.
Imagine that you are going to visit your friend; you get in your car, put the key into the ignition, and start to buckle the seat belt, feeling the familiar resistance.
Seat belts work through a system of extending and retracting. In regular seatbelt systems, the seat belts itself (also called the “webbing”), is attached to something called a “retractor mechanism”. This device works just as its name suggests: through constantly retracting the seat belt webbing that is connected to it. The main part of the retractor mechanism is the spool which is connected to the webbing. Within the retractor, torque takes place through the use of a spring that provides an opposite rotational force from the direct the seat belt is being pulled. This is the resistance you fell as you pull the seat belt out if its casement, before you drive off to the grocery store. The spring is being pulled out of its original form as the webbing its connected to, is being pulled. This also works to prevent excess space between the seat belt and your body. When the belt has slack from being pulled too much, when you buckle in, you’ll notice that the seat belt naturally retracts. This is because the spring, wanting to get as close to its original form as possible, is twisting in the opposite direction and pulling in the seat belt slack.
So now you’re on your way to the grocery store. You maybe turn on the radio, maybe not. You live in California, by the way, away from bustling cities like L.A. and San Diego. Instead, you’re in a woodsy type area, and you have to drive high in what would seem a mountain to any other person, above the beach below. It’s that road that’s always featured in the action scenes in the movie. There is a constant turn that you have to do as you drive along. You’ve always felt at home on this road however, right now you’re panicking because you see a parked car in the middle of the road and you’re about to crash into it, fast, because you’d been speeding, just a little. You quickly stamp on the breaks and feel your body jerk forward with the momentum. You’ve just experienced a rapid change in inertia, however, at this moment, you’re not thinking about the physics behind this phenomenon. Instead you’re tightly holding onto your wheel and staring wide-eye out your window because you realized the car in the road, is a cruiser.
The locking mechanism in your car has done its job protecting you. The retractor mentioned earlier, is also built with some special abilities to handle rapid acceleration quickly. Most seat belts have either of the following locking mechanisms: “systems triggered by the car’s movement” or “systems triggered by the belt’s movement”, according to Tom Harris’s article, How Seatbelts Work. In the first case, the locking mechanism is triggered whenever the car decelerates quickly, as yours did in the earlier description. In the second case, when the seat belt itself is pulled quickly, the locking mechanism activates. Both of these increase safety and it depends on the manufacturer to decide which design to use.
As you know, my groups has started to think about how we’ll go about making a seat belt that’ll let you lay down. However, before we actually innovate upon the old creation, we had to learn how the old seat belts functioned. This was important because it allowed us to see what was good about the old system and how we would have to change it when engineering our own design. Right now, we’re still trying to work out the needs and wants of the potential customers we interviewed last month. This information we help us determine what requirements we need to meet, not just for federal regulation, but customer satisfaction as well. Before I end this blog post, there is still one more thing I have to finish…
Your heart is pounding and you think that this is it. They’re going to find out. When the officer approaches your window, you quickly roll it down.
“Is there anything wrong officer?” You hope you’re not suspected of anything.
The officer, and wide set serious man, stares at you. “You understand this road is blocked?”
You feign innocence. “Why?”
“Well, there appears to have been several robberies within the last couple of hours. Home break-ins that sort of thing.”
“Oh, well, I suppose I’ll just have to try a different way.”
“You do that. Drive safe.” With that, the officer walk off, leaving you relieved and frustrated. How are you supposed to get the stolen goods from your friend now?
StarPathDesign 
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