[tbppjpr]

When I see the features of the Linea, its mentioned that it has 3 point seat belt with pretensioner and load limiter. My questions:

1. Do the pretensioner also react when sudden brakes applied? Has anyone tested it in their Linea or Punto if they have it.
2. How effective the load limiter actually is?

[nkrishnap]

Originally Posted by tbppjpr

When I see the features of the Linea, its mentioned that it has 3 point seat belt with pretensioner and load limiter. My questions:

Yes, as you mentioned the Linea does have the pretensioners and the load limiter.

1. Do the pretensioner also react when sudden brakes applied? Has anyone tested it in their Linea or Punto if they have it.

I have not had a chance to test it out and would not want test it in the real life driving condition too . For the sake of observation, will try this out on an empty stretch of road with hard braking to see how the pretensioners actually work.

2. How effective the load limiter actually is?

How to go about testing this?

[tbppjpr]

Originally Posted by nkrishnap

I have not had a chance to test it out and would not want test it in the real life driving condition too .

Obviously, we are not onto risking lives by doing that on active roads

For the sake of observation, will try this out on an empty stretch of road with hard braking to see how the pretensioners actually work.

When you do that, do not move from your position when car is stopped stand still, because the pretensioner is supposed to lock the belt and it will unlock if it detects some release when you move back.

How to go about testing this?

As per my understanding load limiter is some elastic kind of behavior. Belt won't suddenly lock, it should gradually come to locking position to reduce the harm to the occupant in case of sudden stopping.

[fiat_tarun]

Originally Posted by tbppjpr

When I see the features of the Linea, its mentioned that it has 3 point seat belt with pretensioner and load limiter. My questions:

1. Do the pretensioner also react when sudden brakes applied? Has anyone tested it in their Linea or Punto if they have it.
2. How effective the load limiter actually is?

Originally Posted by nkrishnap

Yes, as you mentioned the Linea does have the pretensioners and the load limiter.



I have not had a chance to test it out and would not want test it in the real life driving condition too . For the sake of observation, will try this out on an empty stretch of road with hard braking to see how the pretensioners actually work.



How to go about testing this?

Actually the seat belt pre-tensioners are connected to the airbag sensors and will activate only in the event of a crash. The seat belt will reverse thus holding you tight so as to minimise airbag burn injuries as well.

IIRC, after a crash where your airbags and pre-tensioners activate you have to change your seat belts as well. These pre-tensioners are activated by a small explosion that causes the seat belt to roll back.

Quoting from an online article - http://www.whyhighend.com/seat-belt-pre-tensioner.html

Electronic/Pyrotechnic Pre Tensioner
This pre tensioner operates with an ECU and a gas generator system in a similar way to the airbag. In fact the electronic pre tensioner usually works together with the airbag and may even use the same ECU as the airbag and that increases its effectiveness.
An explosive charge is used and causes the gas generator to produce a volume of gas. This volume of gas produces a pressure which acts on a mechanical linkage to pull the seat belt. This pre tensioner is usually located in the B-pillar.
Both pre tensioners are designed to slacken off slightly around the same time the airbag deploys, this can be around 30 milliseconds after the collision. This slight lapse allows the passenger to have a controlled contact with the airbag.
Both pre tensioners are intended to be used once. Once a pre tensioner has been deployed the entire mechanism including the seat belts should be replaced. The seat belt pre tensioner can be found on the front and rear seats to provide all round safety and protection.

[nkrishnap]

Originally Posted by fiat_tarun

Actually the seat belt pre-tensioners are connected to the airbag sensors and will activate only in the event of a crash. The seat belt will reverse thus holding you tight so as to minimise airbag burn injuries as well.

IIRC, after a crash where your airbags and pre-tensioners activate you have to change your seat belts as well. These pre-tensioners are activated by a small explosion that causes the seat belt to roll back.

Quoting from an online article - http://www.whyhighend.com/seat-belt-pre-tensioner.html

Ok, in such case the hard braking cannot induce/engage the pretensiors or the load limiters and I was trying to test it.

[tbppjpr]

Originally Posted by fiat_tarun

Actually the seat belt pre-tensioners are connected to the airbag sensors and will activate only in the event of a crash.

Oh, so it means the pretensioners in Linea don't work in the event of sudden braking like the function some bigger cars have. The purpose of reaction with braking is to increase the safety. Its like pretensioner detects the probability of collapse much earlier than the collapse actually happens.

Originally Posted by nkrishnap

and I was trying to test it.

Ha..ha..! And I am laughing here by imagining the 'test result' and your face reaction after the test Good that we got to know this before any harm.

[CrAzY dRiVeR]

Originally Posted by tbppjpr

Oh, so it means the pretensioners in Linea don't work in the event of sudden braking like the function some bigger cars have.

Not sure about bigger cars, but I'm happy these pretensioners work only as per principle, and only when required. In this regard- VAG group cars (Vento for one) had become notorious with the belts getting activated even in the event of fires, and people are trapped to their deaths. Have read atleast 2 such reports in team Bhp too.

[jacksons]

Here is full knowledge for Seat belt pre-tensioner:

The good news is that if you are in a car accident, you can cut your chances of dying in half just by the simple act of wearing a seatbelt [source: Centers for Disease Control]. In addition, faster than a person can even react, a modern seatbelt retracts forcefully to adjust occupants into a safer seating position when the airbags deploy.

How does it do that? With a seatbelt pretensioner, of course. Like a valiant but tragic hero, the seatbelt pretensioner sacrifices its life in an accident, in order to save yours.

Consider yourself fortunate if your vehicle's seatbelt pretensioners never have to see action in their intended purpose. If they do, that means the front of your car or truck has smacked into something else head-on, and pretty hard. It's highly likely the front airbags inflated, too.

The pretensioner mechanism uses an explosive charge to drive a concealed piston when sensors detect the signature abrupt deceleration of an accident. The piston, in turn, rapidly drives the spool around which the fabric strap of a seatbelt is wrapped. That incredibly fast retraction of the belt fabric removes the slack from the belt instantly. This extra seatbelt "pre-" tension, moments prior to the full force of impact, pulls the bodies of the driver and front-seat passenger firmly into their seats. This positions them so as to receive the maximum protection benefit of the front airbags. It also helps prevent the unfortunate phenomenon car crash-ologists call "submarining." That's when the momentum caused by the crash jerks a victim's body under his or her lap belt and sends it careening forward below the dash.

Cars and light trucks aren't the only place in which the use of seatbelt pretensioners has clicked. One of the earliest ancestors of modern, automotive pretensioner systems was one proposed for military aircraft pilots in the 1950s. In 1958, inventor Royce Strickland, Jr., submitted a patent application for a contraption he called a "harness inertia reel." It was an explosive gas-driven device that cinched pilots into their ejection seats before they were blown out of an airplane [source: Strickland].

While few of us will ever have to bail out of a stricken fighter jet mid-flight, it should be somewhat re-assuring to know that similar, seatbelt pretensioner technology will help keep us anchored if we ever get into a head-on car collision.

SOURCE

[tbppjpr]

Originally Posted by CrAzY dRiVeR

VAG group cars (Vento for one) had become notorious with the belts getting activated even in the event of fires, and people are trapped to their deaths. Have read atleast 2 such reports in team Bhp too.

Do one thing to know why such thing happens- Sit in your car, fasten seatbelt, then try to pull it in hurry, it will get locked and when you will try to open the lock, chances are that it won't open. Doesn't matter which car is that, it happens even in Tata Nano or M800 and same happens in bigger cars.

Once the seatbelt is locked, one has to make same space by squeezing back him/herself for some release. Best way in panic situation is pushing the seats back, how many are aware of that? In case of fire or any other emergency, it depends how one reacts in such situation and how he/she handles the panic, doesn't matter which car is that.

If the same doesn't happen in your car, then it means you need a serious visit to workshop to get the faulty seatbelt assembly fixed

My intention to post the query regarding pretensioner in Linea was to find which cars have which type of seatbelt functionality and it was for a chart which I was preparing for my own study. Hence I posted in this thread to confirm the confusion I had on Linea's seatbelt.

[CrAzY dRiVeR]

Originally Posted by tbppjpr

My intention to post the query regarding pretensioner in Linea was to find which cars have which type of seatbelt functionality and it was for a chart which I was preparing for my own study. Hence I posted in this thread to confirm the confusion I had on Linea's seatbelt.

I read the context wrong then. My mistake. I assumed its part of the TJet purchase test drives you were taking for your cousin (upgrading from Dzire, if I remember correctly). Hence my answer compared to competition.

Anyways, what you have described is not related to pre-tensioners at all- I'm sure Maruti would not have missed to advertise if the 800 had one!

Originally Posted by tbppjpr

You are lucky that you could get your hands on T-Jet but there are many others who want that car and Fiat has discontinued that. Recently my cousin wanted to upgrade from his Dzire and asked me some suggestions. I suggested him few cars along with T-Jet. We headed for test drives and found that T-Jet is discontinued.

[nkrishnap]

Originally Posted by tbppjpr

Do one thing to know why such thing happens- Sit in your car, fasten seatbelt, then try to pull it in hurry, it will get locked and when you will try to open the lock, chances are that it won't open. Doesn't matter which car is that, it happens even in Tata Nano or M800 and same happens in bigger cars.

Once the seatbelt is locked, one has to make same space by squeezing back him/herself for some release. Best way in panic situation is pushing the seats back, how many are aware of that? In case of fire or any other emergency, it depends how one reacts in such situation and how he/she handles the panic, doesn't matter which car is that.

If the same doesn't happen in your car, then it means you need a serious visit to workshop to get the faulty seatbelt assembly fixed

My intention to post the query regarding pretensioner in Linea was to find which cars have which type of seatbelt functionality and it was for a chart which I was preparing for my own study. Hence I posted in this thread to confirm the confusion I had on Linea's seatbelt.

I guess what Crazy Driver mentioned about seat belt getting locked in the event of fire is misinterpreted to how the seat belts sort of get locked when one suddenly tries to pull out. Of course, if the seat belts are not working as intended one definitely needs to visit the service center. Nobody wants to sit in the car seat with seat belts on all their life

On the funny side apart, why would a car's seat belt lock up in the event of fire? Are the sensors getting damaged in fire a cause for this?

[tbppjpr]

Originally Posted by nkrishnap

I guess what Crazy Driver mentioned about seat belt getting locked in the event of fire is misinterpreted to how the seat belts sort of get locked when one suddenly tries to pull out....

On the funny side apart, why would a car's seat belt lock up in the event of fire? Are the sensors getting damaged in fire a cause for this?

Its not the event of fire, but the hurrying attempt of pulling the seatbelt and opening the lock in case of panic. Thats why I mentioned, try yourself to pull the seatbelt in hurry, it will get locked at the pretensioner end and won't come out and there won't be enough release left to push it inside the lock to unlock it. To unlock it, you will have to make some space and they gradually pull the belt, it will unlock.

Please watch this video, to understand what I am trying to say:

http://www.youtube.com/watch?v=RWXJO76lMK4

If the belt is being pulled with a force, it gets locked, but we can pull it out if we do that gradually.


My primary intention to ask the question was that do the Linea's pretensioner has any connection with brakes because that feature is found only in bigger and expensive cars mostly.

[CrAzY dRiVeR]

Originally Posted by tbppjpr

My primary intention to ask the question was that do the Linea's pretensioner has any connection with brakes because that feature is found only in bigger and expensive cars mostly.

For Linea - the system works like this -

The sensors of the ‘Air-Bag Smart 2’ system also control the activation of the seat-belt pre-tensioners. The Fiat Linea is fitted with front seat-belts that are each complete with an inertia reel, pre-tensioner and load limiter. On impact, the electronically controlled pyrotechnic pre-tensioner retracts the belt in a few milliseconds, so that it adheres perfectly to the body. The load limiters are positioned inside the inertia reels, and they yield in a controlled manner, metering the force exercised by the belt on the shoulder of the person wearing it.

http://www.italiaspeed.com/new_model...ea/safety.html
The link is for the european linea, but it should hold good for india as well - except for the absence of features like ESP.

Which all cars are having pre-tensioners linked to the brakes? Please post more info.

[tbppjpr]

Originally Posted by CrAzY dRiVeR

Which all cars are having pre-tensioners linked to the brakes? Please post more info.

For example, have a look at the Merc C Class (The least costlier Merc Sedan) specs page and open the 'PreSafe System' link : http://www.mercedes-benz.co.in/conte...s_/safety.html

According to the above link :

"On sensing a potential collision, the PRE-SAFE® system quickly evaluates the situation and triggers preventive measures to protect the occupants. Seatbelts tighten, front passenger seats automatically reposition, side windows close and the tilting/sliding sunroof closing system deploys. If the accident is avoided, the seatbelts are slackened, and the system is straight away ready for action again."


Similarly you can visit websites of other premium luxury brands and can explore the features/specs of various other cars.

[DerAlte]

Originally Posted by tbppjpr

Its not the event of fire, but the hurrying attempt of pulling the seatbelt and opening the lock in case of panic. Thats why I mentioned, try yourself to pull the seatbelt in hurry, it will get locked at the pretensioner end ...

LOL That is NOT the pretensioner - that is only the floating seatbelt 'lock' working.

Pretensioner is a mechanism that replaces the conventional seatbelt spool. Open the B-pillar cladding and look at the spool at the bottom. In cars with seatbelt pretensioners (ARS - Active Restraint System), that spool is a rim-driven motorized spool. When the Airbag sensor system infers an impending crash, the signal goes to the ARS system also - which activates the motor and pulls in whatever slack is there in the seatbelt. This prevents forward movement of torso - even before the 'lock' stops the belt from spooling out.