RedlineMan

Yes;

While the Leatt does not directly rely on the belts in any way, the raised area of the DefNder could be construed to have similar foundational support properties as the Leatt. I'm not a lawyer, and don't know what their patents verbage is, but there could be some (slim) ground here, depending on that verbage.

986

Sorry to be slow... can you clarify how should I read the table? How come some of the values for HANS and Issac are worse than the baseline and injury assessment value?

Thanks!

gbaker

Ouch. Literally.

gbaker

The HANS numbers go bad with lateral shear and bending when the belts slip off, which happens in the SFI test. If you have a full containment seat with head surrounds that probably will not happen.

The Isaac numbers in front/rear bending are exaggerated because the helmet mounts are further to the rear than the installation instructions call for. This was done on purpose (long story). Also, the dummy's head-neck junction, unlike that of a human, is spring loaded so any elevated load on impact will be reflected on the rebound.

Testing to a worse case scenario does not present a design in its best light.

Circuit Motorsports

So I brought my helmet in this morning and installed their posts (they can use the same holes as a HANS) and buckled in and got out at least 20 times. I never had one time where the device was held up on the harness.

The only thing is that if the adjusters end up sliding through the harness guide area you get a bump. Nothing that ever pulled me back toward the seat or would have slowed me down getting out. I got out straight up and to either side with vary speeds to really see if I could get it to catch on anything and it didn't.

I also was curious as to how high the chest part sat and if it was going to interfere with helmets that had a large chin area. My helmet is a Bell T-6 and it has one of the largest chin areas. I didn't notice it hitting the device once during the time I was testing egress.

I normally run my HANS without the pads as it is more comfortable for me to have it that way. That is why I felt it sat higher than a HANS. However the more I thought about it, the device doesn't sit much higher (if any) than a HANS with pads. I won't be able to get a more precise idea until I can have them side by side in my car.

Also I think one thing that people will find as a negative about the device is that for endurance racing where you are doing driver changes it may take a little bit longer to belt in. With the belts being routed so definitively it take a bit more work to be sure they are situated correctly.

RedlineMan

Distinction for accuracy;

Does happen, or can happen?

gbaker

It does happen in the SFI test. Well, the offset test, obviously.

There was a dustup on this subject on another forum where a HANS sales employee attempted to defend the product, claiming we were incorrect in our assertion. He was challenged to produce a video--any video--of the belts staying on on that test, and the readers were served the sound of crickets.

http://www.racingsafetyinstitute.org/HANS%20device.html

The belts come off.

DanR

^ on the video above, were the belt tight? I am amazed at how much the sled moves before it also moves the dummy!


note to self - tighten beltsd even more!

RedlineMan

OK...

My point was to save us from a possible inaccurate generalization. I was trying to differentiate between coming off sometimes or always coming off. I was of course aware that the did come off (I have your footage), but I was not aware of the frequency. I assumed it was not a majority of the time.

Whether the SFI test is realistic or not is another matter beyond that point, of course.

RedlineMan

Hmmmm;

I would imagine the belts are tightened tighter than a seated driver could do themselves. Gregg; Is there a spec for tensioning the belts prior to testing? It seems there should be.

JimLill

This HNR survey may interest some of you......

http://www.surveymonkey.com/s.aspx?s...Y47yT2sg_3d_3d

gbaker

Everyone thinks that. Yeah, they are tight.

John's question is a good one. It comes up often so I made a point of asking the staff when I was in the Delphi lab on Wednesday about a tightening standard. There is no technical standard, although it is possible to preload the belts to a specific value before zeroing out the sensors. They simply tighten them as much as possible. I've seem some technicians put a screwdriver through the loop on the end of the belt and pull.

If you watch that video carefully you can see that belt stretch is a small part of the deflection; most is the chest getting flattened and body being stuffed into the belts in a "C" shape.

I believe that within the test community it is considered a foolish question. As one of the techs said, "The belts will get loaded to over six tons. Tightening twenty pounds one way or the other won't make a difference." Makes sense. They are very careful to check for slippage and breakage though, which can affect the outcome.

gbaker

Nice work Jim.

Sean F

my belts did not come off in an offset hit

lipamax

Guys,
If you'll go with R3, you shouldn't worry about belts and other crap...