No matter how carefully you drive, you may still get into an accident. Good thing vehicles are designed with several safety features that can keep you safe from all sorts of accidents, whether it’s a minor fender bender or a head-on collision.
One of the most important safety features in a vehicle is its seat belts. Seat belts save 13,000 lives annually, according to the National Highway Traffic Safety Administration (NHTSA). So how does a seat belt work? What are its working parts? Do they ever jam? This guide will help you learn more about seat belts.
What Is the Purpose of a Seat Belt?
Your body needs something to stop it from moving in case of an accident, and this is where the seat belt steps in. Seat belts allow you to strap yourself to your seat, preventing you from hitting hard objects like the dashboard and the steering wheel.
The most harmful element in case of an accident is your body’s inertia. If your vehicle suddenly stops, your body will want to continue its forward motion. During regular braking, fighting inertia is easy. However, during a high-speed impact, the inertia is powerful enough to throw your body into parts of your vehicle’s cabin, like your steering wheel or dashboard, and cause serious or even fatal injuries.
Most seat belts have two parts. A lap belt that straps over your pelvis, and the strap that comes from the shoulder and crosses your chest. Seat belts apply the force needed to slow down your body over your ribcage and pelvis. Since seat belts can evenly distribute the forces of a crash over a large part of the body, a person can slow down with significantly less risk of injury.
How Does a Seat Belt Work?
One of the most important parts of the seat belt is the retractor. The retractor is responsible for keeping tension on the webbing, and it’s usually located inside a hidden housing above the passenger’s shoulder. It keeps the webbing tensioned using a spool attached to a spring. When a passenger pulls the seat belt across their body, the spool inside spins, and the spring is untwisted.
The retractor also houses the locking mechanism that prevents the webbing from being pulled during a crash. There are two types of retractor systems that can stop the spool from unfurling. The first type uses inertia. When the vehicle suddenly halts, the inertia pushes a weighted pendulum into a metal bar that jams into a toothed gear on the spool. The weight of the pendulum prevents the spool from spinning any further, causing the passenger to be held in place.
The second type of seat belt locks whenever the spool is suddenly pulled. A lever attached to the spool moves outward when the spool is spun quickly. This lever activates a device that latches onto the toothed gear attached to the spool, preventing it from spinning any further. Both systems are very similar in that they both use a toothed gear attached to the spool. The only difference is the mechanism that locks the spool in place.
What Are the Parts of a Seat Belt?
Buckle
The buckle is responsible for securing the loose end of the seat belt. The latch plate typically inserts into a small slit, and it should audibly snap when you push the latch plate into the slit. The buckle usually also has a red-colored button that unfastens the seat belt. Buckles are typically made from strong materials to ensure they don’t release the latch plate in the event of an accident.
Latch Plate
The latch plate is a tongue-shaped piece of stainless steel that locks into the buckle. The latch plate freely slides up and down the webbing or strap so passengers can freely adjust it depending on the length of webbing they require.
Webbing
Also referred to as the belt or strap, the webbing is the part of the seat belt that wraps around a passenger. Seat belt webbing is made of polyester fibers, as this material can withstand immense loads without tearing. At the same time, polyester fibers can flex a little so that the forces in an accident are distributed over a longer period.
Pillar Loop
Pillar loops make the 3-point seat belt system possible. The pillar loop pulls a segment of the webbing over a passenger’s shoulder. This allows the webbing to be stretched across a passenger’s chest and shoulder.
Retractor
The retractor is the mechanism that tugs on the seat belt webbing, keeping it secure around a passenger at all times. When the seat belt is not in use, the retractor spools the unused webbing into a hidden compartment. The retractor is also responsible for preventing the spool from unwinding in a crash, thus keeping the passenger in place, and preventing injuries.
Seat belts tend to be fairly reliable, but they can still run into issues. The retractor can fail to lock the webbing or the latch plate can detach from the buckle. Replacement seat belts can cost anywhere between $30 to $100, while seat belt buckles cost around $120 to $140.
Why Do Seat Belts Jam?
Seat belts can get jammed, refusing to be pulled out no matter how hard you try. When this happens, it’s likely caused by one of two things. Either the belt has been twisted and has jammed the retractor or the retractor itself is broken. Seat belt retractors are expected to last the lifetime of the vehicle, but they may need to be replaced in case the vehicle gets into a crash. Anyway, it is unlikely for the retractor to be the issue, and the most likely culprit is simply a twisted belt.
Where to Get Replacement Seat Belts and Seat Belt Buckles
Despite their simplicity, seat belts can still malfunction. If you want to keep your passengers safe in case of a crash, you should keep your seat belts in good working order. Jammed seat belts should be properly dealt with immediately. However, sometimes you’ll need new seat belt straps or buckles, as they can break after many years of wear and tear. Luckily, CarParts.com allows you to order new seat belts easily.
CarParts.com offers a vast range of parts at different price ranges. If you’re looking for new seat belts or seat belt buckles, then you should look no further. Use our built-in vehicle selector to see only parts that fit, and check out once you’ve picked your parts. You don’t have to wait a long time for your part to arrive either, since we have strategically located warehouses that allow us to ship your order quickly.
What are you waiting for? Order a replacement seat belt or seat belt buckle here at CarParts.com.
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