gbaker

How tough can it be when the z-axis loads aren't part of the spec?

ltc

Sorry, professional pitfall.
H&D really get under my skin with their Microsoft approach to H&N restraint development.

Juan Lopez

My concern exactly, add that to the fact that Hans does not sell them.....

LVDell

Actually it doesn't. Can you point me to actual testing or results?

exactly.

What is this? http://hansdevice.com/Sliding-Tether-System

Alan Herod

I am still concerned; because of the statement 'regardless of driver's head orientation. Surely there is a preferred head orientation. This is why I asked the question in the first place.

I understand needing to see when pulling back on the track; but, I am not convinced the compromise is worth it.

LVDell

Anybody have contact info (other than a phone #) for HANS or can we get them to chime in?

Matt Marks

I believe there are references out there from HANS that the head essentially "self centers" (it may even have been in my sliding tether packagign) when crash loads are placed on it. The longer tether will start to load up that side of the head forcing it to rotate until the lenghts begin to equalize and provide load distribution equal to the non-sliding tethers.

FWIW - it would seem that this is no different to to what happens with the fixed tethers when you have an impact with your head turned. The same affect would occur....

Alan - once you try the slidign tethers - you'll never go back. your freedom of movement and vision is remarkable.

ApexPerformance

Dealers occasionally receive testing results from Hans (usualy at dealer training events) but they prefer dealers do not publish the data for confidentiality reasons.

I received this from a Hans representative. Their toll free number is 888-HANS-999 if anyone would like to contact them direct.

Granted the sliding tether hasn't been out there all that long, but NASCAR and IRL drivers have been buying them like crazy, and they're loving it. When asked if they can tell the difference in how the HANS worked when hitting a wall with first the fixed tether and later the sliding, nobody has been able to specify any difference. And I know that there is NO DIFFERENCE in how the HANS keeps one's head from flying forward. It works exactly the same.

All things being relative, when the tether tightens up under a g-load, it equalizes the pressure on each side, whether the head is facing forward or not. Each side tightens at exactly the same time. There is no "Z-axis" effect. And it does work exactly like the other 2 tether types.

Please assure these people that the sliding tether has undergone YEARS of testing. We would not have SFI and FIA certification and could not sell it otherwise.

ltc

So something that is SFI/FIA approved (not to mention has an entire FIA spec defining the device) and certified has confidential test results?

So if I understand this logic correctly, if your head is not straightforward at the time of impact, i.e. one tether is 'longer' than the other, there will be NO rotation of the head; rather the head will stay in the same orientation for the duration of the impact since 'each side tightens at exactly the same time'?
That doesn't sound good.

Again, if H&D say so, it must be so.

ApexPerformance

The confidential information that Hans gives dealers may contain results compared to other competitor head & neck restraints.

Here's a link to FIA - http://www.fiainstitute.com/index3.htm

Here's a link to SFI - http://www.sfifoundation.com/

LVDell

I'll stick to my fixed tethers until there is PUBLISHED EMPIRICAL EVIDENCE that supports the stance that there is NO SIGNIFICANT difference between the two types of tethers.

Sounds to me like some people are lab rats in this situation. I just don't see how a sliding system can keep your head from SLIDING, especially on a z-axis in an impact. If you head is not straight and you impact, the fixed tether system will only allow both sides to rotate so much and then stop. With the sliding system if you are not straight on if your head is to slide on that z-axis to "equalize" then what keeps it from OVER ROTATING????

ltc

There you go again....doubting H&D, the SFI and the FIA and NA$CAR.

The next thing you know, you'll be believing that a HANS device always stays under your belts.

LVDell

Circuit Motorsports

Okay, I'll bite and play devils advocate.

If your head is turned and you have fixed tethers it will move in teh Z(ish) axis and come to a fairly quick stop. Correct?

Wouldn't it be intuitiive to think that with the sliding tether it would take this aspect of movement out of the equation?

Just throwing some ideas out there.

LVDell

Joe, both the fixed and sliding tethers will allow you to rotate on that z-axis, but where my question lies is in the rotation past the point of equalization.

Oh Lord, my head is starting to hurt. Time to go pour some Grey Goose martini's

If you hurry you can be here in 20 min!