Automotive Minute: Air Bags
By Bob Brown Dual RSE, HEV, Professor, Motive Power Technician
In this article, we will look at what an airbag system is, what is required for it to work correctly, and the dangers it poses if misused.
People often don’t understand that a safety system can cause more harm than good if used improperly. I see it all the time. This is why I want to pass on the information to keep as many people safe as possible.
The concept of airbags for driver/passenger safety has been around for a long, long time. The idea started back in the 1950’s, and one of the first pilot programs was introduced in the early 1970’s, but it didn’t take off for various reasons. They became common in the 1990’s and took off from there.
There are 2 established names for airbag systems, SIR (Supplemental Inflatable Restraints) and SRS (Supplemental Restraint System), both SIR and SRS are interchangeable and car makers may use either name. Sitting in the driver’s seat of a vehicle, you will see the lettering on your steering wheel stating SRS or Airbag. It’s worth noting that if you look around your vehicle you will see the letters SRS all over your vehicle—steering wheel, passenger side dash, above you head, near the door pillar, sometimes even in your seat!
Anywhere you see the SRS logo there is an airbag behind that logo. Modern vehicles have anywhere from 6 to 16 airbags.
The purpose of an SIR system is to inflate rapidly (small explosive charge fills the airbag in 1/20th of a second, and at approx. 300+ km/h) during a crash event to protect occupants from hitting hard objects inside the vehicle, preventing serious injury.
For the airbag system to work as intended, there are 2 key things that must be done:
- Seatbelt position: Your seatbelt MUST be on and secured properly to ‘hold you’ in the correct spot for the SRS system to work effectively. If you don’t wear your seatbelt, you are asking for serious bodily harm. It must be worn across your waist or hips, not your stomach. In a vehicle accident, you could risk internal bleeding/organ damage if the lap belt is in the wrong spot. Also, generally sit as far away from the steering wheel as possible while still in full control. Most vehicles recognize how close you are to the airbag and will change deployment settings to reduce injury, but there are limits.
- Headrest position: Often a critically overlooked section of vehicle safety, the headrest should be positioned so the middle of the headrest contacts the middle of the back of your head. When you are in an accident, your body will slow down dramatically against the seat belt and SIR system, then ‘whiplash’ backwards against your seat with a substantial force. If the headrest is positioned properly your head will hit the softer headrest and stop the movement, if the headrest is too low, the seat will act as an pivot point and your head will not be restrained and will continue to move backwards and hyperextend causing injury to neck muscles, disks, and ligaments, resulting in severe pain, stiffness, headaches, and dizziness and possible spine damage, or worse. ADJUST your headrest, it’s not worth a potential lifetime of pain. (Whiplash Injury)
When will the airbags go off or be deployed?
The answer, unfortunately, isn’t that simple, a head-on collision with a wall and a head-on collision with a vehicle are 2 different things; some vehicles, as low as 30km/h, could be enough force to trip the crash sensors to deploy. Side impact systems are also a little different.
Just know that the manufacturer has performed a lot of research and development testing to determine when SIR are required to deploy.
Why is it important to keep your feet off the dashboard?
Often, driving in the summer, I see passengers in the front seat of a vehicle with their legs or feet up on the dashboard, which can be a critical, life-altering mistake.
If a passenger’s feet are on the dash when airbags deploy the force can significantly injure the person’s hips, causing full dislocation or multiple broken bones. Accidents happen in a split second; you cannot predict when they will occur, and you won’t have time to move your legs out of the way.
A slogan to help you remember, “You can’t predict a crash… keep your feet off the dash.”
Does my car have a “black box”?
People are often surprised to learn that their car has a ‘black box’ or event recorder, the black box is a device like in aircraft that records major sensors to help figure out what happened or caused the crash.
In the case of SRS deployment, the black box records information relevant to the crash, while the information is somewhat confidential, it is primarily to protect the manufacturer from legal entanglements. What I can disclose is information such as vehicle speed, seatbelt on/off, brake pedal pressed and a whole lot more is collected and can be used to recreate an accident, which is quite rare. It’s worth noting that this device only records vehicle accident data and cannot identify any personal information about the driver.
So, the main takeaway here is not to be scared of the SIR system; it is designed to protect you, but rather respect the system, and it will keep you safe.
BONUS SAFETY TIP: Be sure to remove all objects sitting on the rear window shelf. In a car accident, those items become projectiles. Imagine you are traveling at 100 Km/h and you hit something, you will stop instantly, but the objects around you that are not restrained keep going, imagine being hit on the back of the head with that Kleenex box at 100Km/h!
Have an automotive topic or question you'd like to see covered in another episode of Automotive Minute? Reach out to bob.brown@mohawkcollege.ca
(If you can't see the video embedded at the top of this page, please click the green “Accept Cookies” button.)