RedlineMan

Hey Swede...

Once you got down to car stuff, you did great! As I have mentioned, I myself have not had any real problems with HANS use in relation to the rest of my system. It is not perfect, but close enough not to cause me problems. Probably because my system was right from the start... as one would hope given my line of work and my big mouth on the subject!

You bring up a lot of very good points. It is a complex system these days, and there is much less room for erroneous configurations when using a HANS. Intestingly, correcting these issues to optimize a HANS is a good idea regardless, as most of the common system faults are not good under normal circumstances, let alone when trying to use a HANS.

To make a quick list of the most important points:

- Belt bar height is critical, and probably the most common problem with most belt installations. A slight declination from shoulder to bar is optimal, corresponding to 5-10 degrees. NEVER have more than 20. This puts too much pressure on the back portion of the HANS collar which tends to raise the tips of the yokes and flips the belts off.
- Belts mounted slightly closer together than the width of the neck is highly advised, and even more so when using a HANS. If the distance from seat to bar is 12-14" the belts should be very close together. If over 18" they likely should be crossed.
- Having seat holes that allow proper belt paths is critical. Seats should always allow essentially unimpeded belt paths, ESPECIALLY with a HANS. As Swede mentioned, a new seat may be in order. One of the reasons I am such a fan of alloy seats is that they can easily be modified to correct such problems.
- Shoulder strap cinches should be completely below the HANS yokes. Otherwise the cinches can cause leverage on the yokes that help to flip the belts off.

Swedeboy

Excellent points. I've some minor comments to expand on them.


This is critical even without HANS: With too much declination, an impact will tighten the belts and compress the wearer's spine.

Agreed.

A new seat isn't necessarily in order when improving safety. Just make sure that you get it right the first time. The biggest issue is that not many seat manufacturers offer a choice of seat hole locations, mostly only seat widths. The one size fits all doesn't really apply to seats.

Agreed. Getting the cinches in the correct location is a pain - especially in cars with multiple different-sized drivers.

fatbillybob

Sweedeboy,

With your Euro experience you have undoubtedly been exposed to the 4 shoulderbelt HANS system found mostly in europe and the hybrid 2"-3" systems. Can you offer any pluses or minues to those sytems vs traditional 3" shoulder belts in terms of slippage. Also, does HANS seem to ignore the issue of belt slippage for a reason? For example maybe the primary hit is what kills you and HANS stops that even if you get pushed around like a pinball in the multiple whiplash that follows those secondary hits are sublethal? So maybe belt slippage is not such a big deal???

Swedeboy

At the moment there are only 2 manufacturers worldwide of the HANS device - Stand 21 and Scroth. The 4 shoulderbelt system and the hybrid 2"-3" system are promoted by Scroth, the 3" shoulderbelts are promoted by Stand 21. I mostly have experience with the latter and find slippage is not a major issue once the shoulderbelts have been dealt with properly.

The hybrid system uses 2" thigh belts and 3" shoulderbelts and is therefore essentially identical to the full 3" system. From what I understand, the 4 shoulderbelt system was initially designed for monocoques where there is very little space to strap in the driver and thus the 4 shoulderbelt system helps to create a bit more space at that point in time.

If one were to be sarcastic, one could point out that Scroth are a schoulderbelt manufacturer.

I can't speak on behalf of HANS. However, I don't agree that HANS ignore the belt slippage - it doesn't seem to be a major issue though, otherwise there would likely have been grooves in the HANS device to limit shoulderbelt movement.

Just looking at it from an engineering point of view, there are a few conclusions that can be made.

Firstly, the first hit will typically be the strongest - unless the car ricochets into other obstacles. After that energy starts dissipating - the next hits will typically be less violent. Moving forward is typically where you would expect more damage to be done because there is more room for movement. Moving backward there is the seat with headrest to stop further movement.

Secondly, in a forward movement it would seem the HANS device should function regardless of the positioning behind the belts, purely due to the forces excerted on it. Keep in mind the HANS device really has nowhere to go if it has slipped from behind the belts - it can't rotate and the only movement possible is backwards over the shoulders which is very unlikely.

ltc

Yes, but isn't this possibly the case, with the initial design with 'wings', then no 'wings' and now the latest production design bringing back the 'wings'?

Swedeboy

The latest production design for Europe has no wings.

ltc

Kees,
Now I am confused.
Attached is page 4 from the HANS manual downloaded from the HANS website.
It appears as though the HANS device has 'wings' on the sides of the collar. IIRC, these were NOT there on the 2003-2004 models, as there was some discussion regarding some rennlist users who had orders and got the 'old' design....I'll try and dig up the thread.
Are you saying that these do not appear on the current European (Stand21) HANS devices?
Thanks,

Swedeboy

My apologies - I missed the earlier discussions - so there is some miscommunication here. In terms of wings I was thinking of much higher raised edges lower down on the yokes.

I just checked a brand-new unit and it looks identical to the picture you justed posted. There are slight raises at the level of the shoulder bones.

Kevin M.

Mine just arrived today, it does have the wings and also a ruff velcro type material layed over the 2 long arms, I will test it this weekend and post the outcome.

gbaker

The 4-belt design was developed to address the slippage issue. It was first proposed by David Coulthard as an alternative to increased pressure of the primary 3" belt.

Yes. It makes them look bad.

If the belts come off during a crash it's going to be a very big deal, especially if there are secondary impacts.

Belt slippage on the HANS device is well documented, both in crash labs and on track--even in F1 where you would expect perfect circumstances for that design.

As noted above, the original design employed huge wings running all the way down the front (see initial patent drawings) so we know the problem was anticipated. These complicated removing the belts for egress so they were dropped, which exacerbated the slippage problem. Now they are back.

Don't misunderstand; the HANS is a good product but its fundamental design will cause this problem, along with the egress issue. It doesn't happen all the time, but it does happen.

RedlineMan

Gregg;

As always, a very measured and fair assessment. And as always, thanks for the pro's view! If I can ever find the time, I'm thinking my HANS will be sprouting some wings of its own!

One other reason Coulthard stated for the double belt setup was that most drivers are used to the feel of having belts directly on their bodies. The HANS can lead on to feel "different," and racers are often a fussy lot.

I for one feel VERY well planted with my HANS in place, more so than without it.