Neck Safety Device Comparison (Page 5 of 6)

As one could still buy parts to fix their Defender after they got put out of business, I think they may well be able to sell parts to fix them if and when they get put out again.

I have to confess, I really don't get the animosity toward HANS for asserting their patents.  They were AFAIK first to market, and got into this stuff well before there was a big demand for it.  The patent system (which is established in the Constitution) is intended to encourage that kind of innovation.

I can understand griping about the SFI spec, if that does in fact require a design covered by the HANS patent portfolio to comply---I don't have familiarity with either the spec or the patent portfolio, so I can't say whether it does or doesn't---and there's no RAND restriction on the involved patents, but that's a separate issue from the patents themselves.

(edit: the issue with a patent-encumbered standard for something hardware like this is more whether the patent is licensed on reasonable terms to all comers than whether there is an encumbrance at all, in my view.)

As far as helmet mounts go, got an Isaac used, took 3 weeks of calls and emails to get a response to a question.  Ordered the parts, 2 weeks later, they still hadn't shipped.  Cancelled everything and are still looking for a team neck device.
My .02

Here's the text from Leatt's list of press releases, which clearly show that they sued DefNder:

http://www.leatt-corp.com/stat_archive.htm

I actually haven't found anything more than forum posts that say that HANS sued DefNder as well.  This thread:

http://www.trackpedia.com/forums/showthread.php?t=4925

at least links to an article that appears like it could be possibly legit, but the link isn't active anymore, so who knows.  This thread makes it sound like HANS was pretty reasonable with the whole deal:

http://honda-tech.com/showthread.php?t=3010004

Particularly posts 13 and 14.  Who knows what's true.

I emailed NecksGen a few questions and just got a response email:

-The tether can slide, so you can move your head

-The SFI test results are going to be up on their website shortly

-They have units built and ready to ship

-They don't have a rent-to-own option, and they won't send me a unit to test out and show off at Infineon (can't hurt to ask, right?)

The Foam Neck Ring would never be better in any situation. 

As for Side impact rating I believe some of the non-HANS devices have better ratings than HANS based on this thread, just skim back through it.

That said the problem that this was created to solve, frontal accident basal skull fractures, all devices work just as well from what I can see.  Side impacts weren't killing or disabling people, only those frontal impacts were.

That's interesting data, because what it shows is that every device other than the Isaac works to multiply lateral shear forces. I'm not saying it's right or wrong, but interesting. The only way that I can see a HANS creating a multiplier effect in the Fy axis is if the sideways force applied induced a Mz force that was then measured on the Fy axis. Mebbe?

My guess on the increased lateral shear load is that the HANS device serves to concentrate the load in one spot.  This is because there's a hard object (namely, the brace) right on the corner between your shoulder and your neck.

I'm guessing your neck can normally curve smoothly and distribute the load evenly; but if there is a hard brace right there, there's a sharp point where all of the load is focused. 

A seat belt might do the same thing, but it also might have enough give to not be as bad as a hard plastic brace.

The Leatt brace looks like it goes further up your neck, so it wouldn't generate this effect as badly, but it would still do it...and sure enough, the Leatt brace increases the load a little bit, but not as bad as the HANS device.  I wish we could get the shear values for the R3 and the Hybrid models to see if this idea is correct, because they don't really have anything right in the crook of your neck and shoulder.

To argue against the point I just made, though....if that explanation is correct, I would expect the lateral moment to increase as well.  In this graph:

The lateral moment is high, but it is reduced from the baseline.  If the lateral shear went up because of a hard thing being on your neck, I'd expect the lateral moment to go up as well.  But it didn't.

Yeah, that's why I was focusing on maybe a Mz multiplier. The HANS just has the tether that's attached at 2 points on the device and at 2 points on the helmet. If the test was done such that the vector of the force applied is purely in the Fy direction, then I could imagine that a HANS device could max out its lateral travel on the force-applied side of the Fy vector, which could then result in that load going into a Mz twisting motion, which (depending on how the test measurement device was arranged) could appear to be an additional Fy force.

Say, for example, that the test is using some version of a dial indicator like you use on a machining stand. If it's set up so that the end of the indicator is in the Fy vector, then when the helmet twists, it would force the rod into the dial indicator further, resulting in an apparent increase in Fy, when really it's showing the effect of an Mz motion.

I'm not saying that's what happened or how the test was constructed, just how it could have happened. It just seems odd that you'd have a true multiplier effect.

I have a HANS and have worn it in several races now. If there's slippage of the body under the HANS, it's going to be pretty limited unless you don't have the belts tight. I've found that I feel more locked into the seat and the belts with the HANS on than when I was just wearing the foam dog collar neck ring. My HANS device has the sliding tethers and I haven't felt like it limits the rotation of the head to prevent/limit sideways vision in any way. But that's all just anecdotal.

In this video:

http://www.youtube.com/watch?v=0RinuSRqMaM

You can see the person slide forward for a bit, and the HANS device stays stationary until all of the slack is taken out of the tethers.