Mike A.

I wanted to buy the Schroth 2"/3" Hybrid to help prevent the belt from slipping over the outside lip of the HANS. I called the people at HANS and asked if the hybrid belts would be better. The answer I got was that they believe the hybrid belts are not any better than the 3" belts and in fact if the belt does slip over the lip, the belt will hold the HANS in place more securely.

I really don't have the slippage problem with my 3" shoulder belts, maybe I should.

fatbillybob

Mike A. ,

Belt slippage has been seen on impact. No impact = no slip. A few people with specific body type, specific seat, specific mount specfic belts do get routine belt slip under use. HANS of course wants their device to be universally applied. If they could they would certify it with a three point. If this was not an issue HANS would not haev changed the mount points of your belts over the years, changed the design from patent conception, to no lip to lipped HANS. Further, Scroth who I trust more than HANS would not design a 2/3 hybrid and tested its effectiveness, and they would not have designed the 4 belt dual shoulder strap system that they have also tested and proven. The science of safety is constantly changing moving target. I think we will see 2" lapbelts as the future standard. They have been shown to control hips better than 3" and are already standard equipment on the gt3 cup cars (90% sure on that).

DJF1

Sorry to say this, but Isaac sounds better and better everyday...

kary993

As I understand it from one of the largest distributors of Hans, is the slippage is normally due to the fact that the shoulder belts are not maintaining the distance apart and is widening during use. This will cause the slippage off the hans device. They said that if you maintain the separation of the shoulder belt as mounted on the roll cage for example, this slippage should not occur.

Just passing on some information. This issue, of course does not occur with the Isaac .

Swedeboy

The correct installation and adjustment of the shoulder belts is key in retaining the position of the HANS device. Often this will require the driver to readjust his driving position, which may or may not be uncomfortable at first. A enlightening way to check the configuration of the belts is to have a helper take some pictures with you strapped in the car.

Note the Schroth double harness may lead to unsafe situations in the event of a heavy crash when marshalls and other safety personnel aren't aware of the extra buckles and trying to extract an unconscious driver.

RedlineMan

Hmmm...

I think it is worth noting (again!) that the HANS was desigend for RACE CARS, predominantly open wheel cars with highly laterally restrictive cockpits. Race cars can be configured any way the driver needs them to be. Street cars limit the number of options dramatically, and these limitations take the HANS further out of its optimal design range. The variations in HANS design have a lot to do with trying to make them more universal, I'm thinking.

Regarding safety crews and crashes. If the situation warrants it, professional safety crews will simply cut the belts in seconds and get you out. The extra belts of the Schroth 4-strap will pose no extra difficulty.

fatbillybob

Actually, the dual shoulder does not have this problem in practice but may in theory. I have them. What happens is that when the body belt is released the tension on the HANS strap lossens and the whole mess comes off with one turn of the CAM per many sactioning bodies requirement.

fatbillybob

Agreed, After buying my HANS and leaving ISAAC doing the research ISAAC integrates better with minimal safety gear of most of us with just a 5 point and a racing shell. Once I committed to using the HANS my car has to be converted to more of the NASCAR look with full containment seat etc... But HANS will never tell you this. Their party line is that HANS works if you wear it with 5 points period. I think it really comes down to trying to get informed on the +/- of a device and select for personal needs. I glad guys on this list share how they really use these devices. It really helps those who do not have them yet.

ltc

Perhaps it may be worthwhile to invest $65 in an ISAAC rental program:
http://isaacdirect.com/html/product.html#Rental
and try the device, compare it to what you may or may not currently have.

I don't think there is anything to be 'sorry' about regarding H&N restraints and the discussions that surround them.

JCP911S

Not sure I want to test ANY H&N device in realworld situation.

BTW... i figre HANS is better than nothing but probably requires a full containment seat to protect in hard lateral hits

ltc

Assuming that a full containment seat will guarantee the belts don't slip off.
I am still unclear as to how that works.

RedlineMan

Hey;

I am toying with testing an Isaac at the very least so I can compare them in battle and give authoritative accounts of BOTH of them.

The idea behind the containment seat augmenting the HANS is that the shoulder "fences" and "halo" of the true containment seat will allow less of the lateral movement that would tend to pull the belts OFF the HANS. In this regard, a containment seat is much closer to the true intent of HANS usage; employment in open wheel cockpits.

ltc

John,
I agree with your assessment; a 'lay back' seating arrangement (re: open wheel cockpit) is much more suitable to a HANS.

However, given the shape of the HANS as fitted to a human chest in a 20deg version, my concern is, that in forward motion resulting from impact, the belts WILL slip off. There appears to be simply too many factors working in this direction (initial setback angle, belt stretch, initial dressing of the belts down and away from a tangent plane of the chest/harness interface).
In this scenario, the side bolsters/HALO/seat containment don't become a significant factor.

In an angled impact, then yes, they would.

In a more side impact, please continue reading below.....

It is interesting to note that while researching driver nets (not window nets) Safety Solutions (www.hutchensdevice.com) has an interesting graph and photograph, specifically for a HANS situation:

http://www.hutchensdevice.com/driver...R_NET_INFO.pdf

It is unsetllting to note that in the photo at the bottom,
THE HANS DEVICE IS CLEARLY NOT EVEN CLOSE TO BEING UNDER THE BELT!
This photo simply added to my initial and continuing concerns regarding the HANS in a sedan environment.

I am still trying to research the HANS in WRC cars, which appear to have similar setups to our Porsches.

fatbillybob

To me it is interesting that HANS never specifys how it should be deployed. Tests show in the one dimensional sled hits even with non-containment and 5 points it works fine. The problem is that many hits are the pinball type. That's when the ISAAC shines because of its lateral abilites even with non-containment. So HANS just points to the one dimensional hit and expects us to accept that. Those who do even minimal research find that hits are not one dimensional and question what happens on the 2nd and 3rd order hit. F1 and NASCAR thinks of this and their cockpit design bears that out. Thus the advent of enclosed cockpit design to enhance the function of HANS or make up for its ability to really only function in the one dimensional forward impact. Thus the fencing keeps us going front to back which is where the HANS works best. John I have used ISAAC for about 2 years and HANS for about 1 year. The ISAAC is a much easier device to live with except when you have to initially put it on and during driver changes. I wheel to wheel but have never traded paint or met a wall so I have never tested either device and I never plan to. I have succumbed to the SFI 38.1 spec for whatever that is worth, and Thinking the pros know something I don't. I have simply joined the bandwagon but I think the engineering of ISAAC (I am not an engineer) is more sound. Fundamentally I also believe that nothing should be allowed to trap a driver and the choice between single realse vs. trapped with a device around your neck is a difficult one. Many of us do not have to make that decision because many bodies now require single release therfore no ISAAC. However, I think it would be much safer to have the HN device stay in the car just like the ISAAC and be required to not detach or slip off the harness. How rediculous would it be to have to hit a single release to detach 5 or 6 points at the mounting points instead of the cam and walk out of a burning car with 6 straps hanging off? If that is rediculous then why do I have this HANS thing hanging on my neck? Argueably it is just about as likely to trap me as dragging 6 belts along for the ride. But the powers that be, SFI 38.1 written for HANS, said it should be that way. So what's a driver to do? Sounds like a beer commercial...tastes great....less filling!

YMMV

DJF1

Thanks Lewis, my point was a bit on the sarcastic side for the HANS... I'm very familiar with the ISAAC, I flerted with one at Sebring, in retrospect I sould have gotten one, I had the perfect oportunity to test it that weekend

Seriously the only thing that has kept me from getting the ISAAC is the certification. While the mantra that any restraint is better than nothing, at this point I'm not convinced that the HANS will actually do more good than harm in certain circumstances. While it is true and tested in close cockpit situation, we the club racers, have jumped the bandwagon on the assumption that its the best even with our normal safety equipment, here you go with the picture from your link that is extremely distrurbing! Not only the hans is off and the one side is really cutting into your throat, the belts now are loose because of the hans slippage. So its a double whammy! In reality you risk a more serious injury than without it! In my accident at Sebring it was a rear side impact , pretty hard I must say, but the belts were tight and held me were I was supposed to be! I cannot even imagine what you see in the picture happening to me...I really dont want to.
Yes I agree with you that all this talk is extremely usefull. At this point I'm pretty convinced that HANS is not in my future maybe the R3 or the ISAAC. I really wish the ISAAC goes through the certification though...