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School me on airbags....

Emmettology 101

Emmettology 101

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I've thought I heard over the years that airbags are supposed to go off in the event of a front end collision over 5 or 10mph.... Is this true? And how are they supposed to work(what speed do are they supposed to deploy at, what type of impact is needed, etc..)...

A friend of mine was in an accident with an 02 Dodge 3/4 pick-up 4x4 Cummins. Hit a tree head on at about 30mph. The impact was about dead center of the truck slightly bend the frame ends and serverely bending the front frame crossmember. The airbags never deployed.
 
I've heard that it varies a bit from vehicle to vehicle but are supposed to deploy between 5mph - 15mph depending on the location of impact. You might want to check with dodge in some way to find out. Also, was he the original owner? If he bought the truck used, did the previous owner have the air bag disconnected?
 
Muddytazz said:
I've heard that it varies a bit from vehicle to vehicle but are supposed to deploy between 5mph - 15mph depending on the location of impact. You might want to check with dodge in some way to find out. Also, was he the original owner? If he bought the truck used, did the previous owner have the air bag disconnected?
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Yes, he bought the truck used.. But I know the original owner. Will check with him, but I dont think they were ever messed with. The truck was definately going more than 20mph, closer to 30.... Hit pretty much dead center... Myabe off to the pass side a hair..
 
So far I've found this


What is meant by a "moderate or severe" crash?
Frontal air bags are generally designed to deploy in "moderate to severe" frontal or near-frontal crashes, that is, crashes that are equivalent to hitting a solid, fixed barrier at 8 to 14 mph or higher. This would also be equivalent to striking a parked car of similar size at about 16 to 28 mph or higher.
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The Airbags will not go off in every instance. They are made so that they will only go off if the impact is great enough to need it. I know that may sound dumb but you can get hurt much worse if it went off and you didnt need it. The two stage airbags they have in cars now are amazing


Thinking back to older cars. The crash sensors would literally have a steel ball (like a ball bearing) inside and the bags wouldnt go off unless it pulled enough G's to move the steel ball.

Now instead of steel balls they use pressure sensors (inside doors) for side impact bags, and electronics like an accelorometer on the front to determine wether or not to set them off.

Thats just from my knowledge of working on cars (mostly BMW stuff). From car to car will differ some but they all work about the same.
 
i worked for a honda dealer for 5 years and i was always told on honda's that there were three air bag sensor's, two on the fornt bumper and one just behind the drivers side door and to set off the airbags you had two hit two of the sensors. i dont know if this true in most cases but i saw several cars that the airbags didnt go off and we usually only found one crushed sensor
 
There are actual direct impact sensors and inertia sensors(steel ball in the sensor that is moved by enough Gs). He likely didn't hit directly on one of the direct impact sensors and wasn't enough Gs to set off the inertia sensors. This is the very basic knowledge I remember from that class, if I get the motivation I'll pull the book out and refresh myself on the subject(could use a refresh anyway).
 
sled_dog said:
There are actual direct impact sensors and inertia sensors(steel ball in the sensor that is moved by enough Gs). He likely didn't hit directly on one of the direct impact sensors and wasn't enough Gs to set off the inertia sensors. This is the very basic knowledge I remember from that class, if I get the motivation I'll pull the book out and refresh myself on the subject(could use a refresh anyway).
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The impact was pretty harsh... Enough that the drivers hands bent the steering wheel..... The front bumper looks like a U.. The bumper was flattened and pushed back into the intercooler and that was pushed into the radiator. I think the rad maybe have been pushed back far enough to touch the engine... The grille now sits back a good 8-10 inches or more. There is a round tube crossmemeber behing the bumper. It is bent back into a U shape also and was betn far enough that the middle of the tube tore....

New news... The insurance company is going to fix the truck. :( Damage estimate is around $10k... The adjuster said since the truck is worth quite a bit, there owuld need to be about $17k worth of damage. I guess they are even fixing some frame damage.
 
Update...

Here's pictures of the truck...

P1280005.JPG

P1280004.JPG



Damage total so far is up to $14000... The core support/intercooler/rad was pushed back into the engine. Bent most of the pullies, waterpump and busted the timing chain cover... The engine was pushed back bending and ttearing the engine mounts. The front crossmember in the frame was also bent into a "U" shape and torn......
 
The actual answer to your question is simple. The airbags deploy when the sensors tell them to. To do that, the impact must be "sudden" enough for the sensor to react to it. It is not really speed dependant, although some will not deploy before a set speed in older models. Frame impact is usually what deploys them. The reason for that is that when other parts of the vehicle hit something, those parts crumple much easier. The frame impact is a harder hit than the body, at any speed. Sometimes a vehicle will look like sh!t and the airbags will not deploy because there wasn't enough "sudden" impact. Then again, you may see a vehicle with deployed bags and no visible damage because they ran over something big enough to hit the frame or a spot real close to a sensor. BTW ...different vehicles have different sensor quantity and locations.
I have seen a big pothole set bags off. I have also seen a destroyed front end with no deployment because the car ran underneath a larger vehicle. The vehicle hit, pushed the car down, which(in the time frame of sensor reaction) slowed the impact down.
Hope that helps.
 
Leper said:
The actual answer to your question is simple. The airbags deploy when the sensors tell them to. To do that, the impact must be "sudden" enough for the sensor to react to it. It is not really speed dependant, although some will not deploy before a set speed in older models. Frame impact is usually what deploys them. The reason for that is that when other parts of the vehicle hit something, those parts crumple much easier. The frame impact is a harder hit than the body, at any speed. Sometimes a vehicle will look like sh!t and the airbags will not deploy because there wasn't enough "sudden" impact. Then again, you may see a vehicle with deployed bags and no visible damage because they ran over something big enough to hit the frame or a spot real close to a sensor. BTW ...different vehicles have different sensor quantity and locations.
I have seen a big pothole set bags off. I have also seen a destroyed front end with no deployment because the car ran underneath a larger vehicle. The vehicle hit, pushed the car down, which(in the time frame of sensor reaction) slowed the impact down.
Hope that helps.
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Yes, that helps.. But what gets me is that this accident was a sudden and hard hit. Enough to move and engine back, yet the airbag did not deploy... Only thing I can think of for why they didn't(other than being faulty) is that we didn't have our seatbelts on and maybe the comp sensed that and didn't trigger the bags? :confused:
 
Emmettology 101 said:
Yes, that helps.. But what gets me is that this accident was a sudden and hard hit. Enough to move and engine back, yet the airbag did not deploy... Only thing I can think of for why they didn't(other than being faulty) is that we didn't have our seatbelts on and maybe the comp sensed that and didn't trigger the bags? :confused:
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The seatbelt thing would do it.
But remember, we are talking thousandths of a second. As soon as the first part of the truck hit something it was slowing down real fast. The body absorbed the main impact, and then the radiator and engine pulleys. The engine is mounted in rubber mounts, so they flexed and/or broke.
I still thing no seatbelt caused no airbags.
 
Leper said:
The seatbelt thing would do it.
But remember, we are talking thousandths of a second. As soon as the first part of the truck hit something it was slowing down real fast. The body absorbed the main impact, and then the radiator and engine pulleys. The engine is mounted in rubber mounts, so they flexed and/or broke.
I still thing no seatbelt caused no airbags.
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Ya, the seatbelt thing is what I am wondering too...
 
You were NOT wearing your seat belts? Dumbasses, buckle up. If it was a few more miles an hour you would probably be dead. As it is I'm surprised no one was seriously hurt. BUCKLE UP, it saves lives. Now with that out of the way...

I think something is wrong with those airbags or with the sensors. Not wearing your seat belt would not prevent the airbags from deploying. Air bags were initially designed to protect someone who was NOT wearing their seat belt. If you wear a seat belt, the air bag is not really gonna help you much anyway.

P.S. The title should be, School you on wearing your seat belts.
 
MaxCrack said:
Air bags were initially designed to protect someone who was NOT wearing their seat belt. If you wear a seat belt, the air bag is not really gonna help you much anyway.
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Where did you get that idea. That is incorrect.
 
Air bags are a supplemental restraint system. They supplement your seat belts. Your bags probably should have deployed, but with no seat belts on you may have sustained even more injuries by being thrown into your exploding airbags. Ask the repair shop if you can watch when they explode your old bags, you'll wonder why the hell they have the word air in the name! After I saw the first set go off in the shop I used to work in, I have always had a lot of respect for the power in those things, the videos you see just don't convey the real power. Please wear your seat belts, I've buried 2 friends from 2 different wrecks that everyone else walked away from with minor injuries, they both were the only ones not wearing seat belts.
 
Leper said:
Where did you get that idea. That is incorrect.
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I think maybe it is correct.

http://www.usatoday.com/money/consumer/autos/mauto133.htm

1969, first line.

I've heard it before, but I can't find ANYTHING proving that the first cars sold to the general public with airbags (the Toronado) did not have seat belts where there were airbags.

1977 Carter mention also seems to imply it was an "airbags or seatbelt" issue, not both.

Kind of interesting, I had always believed airbags were first deployed as an attempt to get rid of seatbelts, because you can't force people to put them on. :)
 
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i was driving my sisters 2001 grand am and a lady pulled out in front of me. i hit her on her side going 40 and the air bags did not deploy.. im sure there are some kind of sensors or something that let the airbags know when to deploy but maybe the sensors in that truck felt there was no need? im not sure
 
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