Seatbelt | How does it work?

Everybody knows what happens in an accident if you don’t wear a seatbelt. What you see in this accident looks really painful in slow motion. Modern seatbelts are not just mechanisms which arrest your motion; rather. they cleverly allow enough movement to minimise internal injuries and help you land safely on an airbag. In this video, we won’t just learn the working of a seatbelt; we will learn why modern seatbelt mechanisms are designed the way they are. So buckle your seatbelt, and let’s start a design journey.

[impastdeath]

The three point seatbelt was invented or designed by volvo and they left it patent free so that every vehicle manufacturers can use it

[gaeb-hdlf]

Crazy how much thought and engineering goes into aparently simple things

[magicdolphin]

Hats off to this girl, she risked her life multiple times just to show us how seatbelts work.

[justuslm]

There is a small mistake in this video: The seat belt pretensioner usually doesn't react to brake pedal movement, but rather to the airbag sensors. This means it only triggers when the g-sensors in the front of the car detect a collision, not before that.
The advantage of this is that it doesn't go off in a situation where you brake strongly but don't have an accident, for example when you manage to prevent an accident. Since the pretensioner is a single-use device, such a maneuver (even in a voluntary driving safety training, rather than an actually dangerous situation) would make it impossible to use the pretensioner in an actual accident.

[bradnoyes]

I see forms of this question coming out multiple times in the comments: "Will the seat belt pretensioners fire in a sudden braking event?" Short Answer: No. Long answer: The video is mistaken, the pretensioners do not fire before an impact, the airbags and pretensioners fire when (depending on the system) the vehicle's impact sensors are triggered and/or an accelerometer in the SRS module detects an impact. When the vehicle hits something, there is time between the initial impact and the vehicle coming to a complete stop. This time is the time in which the occupants of the vehicle must be safely decelerated from the vehicle's pre-collision speed to a stop. The most serious accident is when a vehicle hits a stationary 'non deformable' object (such as the rock in the video). If the vehicle had a 'rigid body' chassis (term used in theoretical physics to mean undeformable) then the vehicle and occupants would have to decelerate to zero instantaneously, resulting in massive injury or death to the occupants. Obviously this is theoretical, and the chassis of the vehicle bends and deforms, all the while decelerating the passenger compartment and therefore the occupants (this is the reason for crumple zones, they are sacrificial components of the vehicle intended to absorb the energy of the vehicle and decelerate it at a rate that is more safe for the occupants. This increases the time from which the initial impact occurs to when the vehicle & occupants come to a stop. During this time after the initial impact, the SRS (Airbag) module uses accelerometers, in many cases additional 'impact ' sensors, and occupant weight sensors (specific layouts vary from manufacturer to manufacturer and model to model) to compute the severity of the accident, determine which aribags/pretensioners to deploy and in some cases how quickly to deploy them (some aribags have multiple stage deployments), all in fractions of a second (down to as little as 10ms in some cases) and before the force of the impact reaches the passenger compartment.
Edit: Note some vehicles do not use 'pyrotechnic' pretensioners (pretensioners that use an explosive charge like the pretensioners described in this video). These Vehicles have different controls, and I am not familiar with these systems.

[swaygfx]

she really didn't see that boulder in the road tho?

[alok]

Is no one gonna talk about how much accidents she went in for us

[kogure]

Don't you hate it when there's a massive boulder in the middle of the road

[ezvqfdt]

She's braking with her left foot...

[Serenity]

Hey man, 7 years ago I was really wondering how this works. I couldn’t find anything on the internet that was accessible to me and even my physics teacher didn’t know.
But I’m very proud to say that my 14 year old self figured out the part with the steel ball.
Thank you for your animation, this was really interesting!!!

[kkoz]

Lost my father to him not wearing his seatbelt, my life would have been much different if he would still be here. I don't know why anyone wouldn't wear a seatbelt your chances of surviving are so much greater.

[manjunathsanjeev]

Finally we got a new girl to drive your cars.

[knetknecht]

This high quality video is the kind of content, which is needed on YouTube. Not those reaction vids, let's plays or beauty blogs.

Good job!

[avimango]

A recent car accident in Gujarat state of India when a famous industrialist was killed and the reason was the non-fastening of the seatbelts by rear passengers. With this background, people are getting paranoid about the working of seatbelts! There is a doubt if the seatbelt shall operate or not in case of crashing of the vehicle! Whenever one sits in a unknown car one should apply a quick tug and the locking mechanism will lock the belt. Seatbelt is a simple mechanical device based on centrifugal force- no sensor, no electronic signal etc etc.A quick tug and the locking mechanism will tell you that it is working as required.
Knowing fully well about functioning of Seat Belt one should never forget to put on the seat belt before starting the vehicle. Your video has explained it in all respects ! Thanks 🙏

[Toho_Nightmare]

Imagine someone rips your seatbelt off and your door only to explain how a seatbelt works while your about to crash into a boulder 💀💀💀

[infantnelson]

Really loved that illustration. Thanks to make easy understanding, how seatbelt is most important.

[iijj]

Several hours ago I in my car wondered how does a seatbelt work. Now I opened YouTube and the first thing I saw in my subscriptions is this video!

[Xanthopteryx]

Fun fact:
Volvo have electric pretensioners on newer cars. So the car can actually pretension the belt BEFORE an accident has happened. They also have, since long back, TWO explosive devices - one at the top mount (as shown here in the video, where the roll is) and one at the bottom mount (where it is fastened between the door and the seat). This is because this saves lives since it tension the belt in a better way.

[oekfoh]

Never in my lifetime would I figure out how to design something as simple as this

[derwolf]

6:25 Looking at the massive wobble movement of the front wheel, I am sure even if she didn't crash into the boulder, this imbalance means that her lug nuts are so loose that the front wheel will fall off in less than a mile of normal driving anyways. ^^


No just a joke, love your great animations and couldn't do it better, thats just one thing that fell into my eyesight.