Harness mounting points

[Flat Eric]

4 point harness

What angle should the should the shoulder straps be, between chassis mounts and shoulder.

Trying to mount seats lower in car, just want to make harnesses are still ok.

Seem to remember that they should be either horizontal, or (and this is where I can't remember) the mounting points needs to be lower than shoulders(or should it be the other way round).

[Liam]

(or should it be the other way round).

Yes

[BuGsBuNnY]

mounts higher ideally otherwise your spine will be compressed in case of an accident...

[adhawkins]

Really? I don't think I've ever seen a Westfield where the harness mounts are higher than the driver's shoulders. Certainly neither of mine have been.

Andy

[BuGsBuNnY]

There is a difference between what should be and what is...

[adhawkins]

I would have expected something like this to be part of SVA though?

Andy

[studbuckle]

SVA requirement it:

minimum distance of 45cm between the bottom of the seat and the top of the seat belt mount.

Where the distance is a vertical distance and the bottom of the seat is judged to be the lowest point of contact

[adhawkins]

So as long as you're less than 45cm from shoulder to you're Ok...

Andy

[Mark Stanton]

mounts higher ideally

Mounts higher than your shoulders How does that work with saloons and rally cars for example where fixings are taken down to floor level ? behind drivers and passengers

[studbuckle]

Yes but by that criteria It would suggest that more is better and therefore higher is better as was suggested above.

Of course you then get into the torsional strenghts of a vertical pole mounted on top of the chassis rail. The shorter this is the stronger it is. So pointing points directly on the chassis rail will be stronger but mounting points mounted on 20cm poles would be safer. therefore current arrangement is a compromise to a certain extent

[studbuckle]

mounts higher ideally

Mounts higher than your shoulders How does that work with saloons and rally cars for example where fixings are taken down to floor level ? behind drivers and passengers

same compromise: fastened to cage or to floor is stronger than roof but risk of compression greater

[nikpro]

This is not correct!

The main purpose of a harness is to keep you in the seat in any form of accident. the best mounting point for the shoulder straps is below shoulder level because if the vehicle rolls it keeps you in the seat better and stops you slipping upwards.

[studbuckle]

that point of view contradicts the view of the SVA test.

I'm not saying I know the answer, just pointing out what can be summised from the regulations.

[Westfieldman]

If you use EYE bolts in a loaded angle of 90 deg like in a Westfield you have to derate the eye bolt by 80% so a 1 tonne eye bolt will become unsafe at 200kgs

The size used in a Westfield are approximatly [cos they have no SWL on them] 500Kgs so 100kgs is the limit in the 90 deg plane as used in a Westfield

Working load limit for a 7/16" Shouldered eye bolt is 1800 lbs.

1 800 lb, lbs = 816.466 266 kilogram

So 163.29kgs

[studbuckle]

and presumably Paul that eyebolt into a post bolted onto a chasis rail would further derate the effectiveness?