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Location: Adelaide
Registered: May 2002
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Re: Why do people get roll cages?
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Tue, 16 November 2004 12:22

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Ahhh, a thread close to Rex's heart...
Standard seatbelts do not provide controlled deceleartion of body mass.
They are one the most compromised piece of safety equipment in the modern automobile. They are designed to: (a) retract out of the way, when entering or exiting a car, (2) Cater and work the same across all body shapes and sizes, (3) LOCK on sudden extension to tie the body to the vehicles mass and (4) be easy enough for any bonehead to use
When the occupants body lurches forwards, the reel LOCKS solid. No control of deceleration whatsoever. The usage of pre-tensioners further highlights this. Pre-tensioners are often used as part of the SRS system. an explosive charge in the reel causes the belt to pull tight the instant the SRS system is triggered.
Controlled deceleration is only built into crumple zones, airbags and padding.
Harnesses are surely a gift from god to restraining systems. The massive increase in surface contact to the torso has a huge affect on how forces are applied to the human body.
As good as they are, they are not used explicitely for the following reasons.
- ADRS assume occupant laziness/stupidity, in that not every person is going to adjust the harness for a proper fit each time they use the vehicle. Retractor belts do this automatically.
- Harnesses are more complicated (emergency crew stupidity) than reciever type buckle seatbelts to release an occupant from in the event of an emergency.
Neck injuries are impossible to prevent without making the head part of the cars mass as a seatbelt/harness does or a neck brace which is in no way a match. For example head rest and wings for rearward and sideways movement and a strap across the forehead for forwards movement. In this respect helmets are bad because they increase the mass of an occupants head. But it is better to have a sore neck than pieces of your brain in the passenger footwell and smeared across the roll cage
Rollcages perform 2 functions. Increase vehicle stiffness so the suspension performs its best and protect occupants in event of roll over and side impact. Front and rear impacts are still absorbed mostly by the vehicles body.
The cage must tie rigid all four suspension corners and prevent the body from flexing or twisting and transfer/distribute forces throughout the structure with minimal deformation.
This is why competatiion rollcages are very complex and very heavy.
Less serious roll cages filter on down through the levels to where simple half cages and 4/6 point bolt-in cages acceptable.
Then there are wank cages, which although them may perform very well are over-kill and simply add a mass of weight to a car which may only require a simpler cage. These types of cages usually kill people because they are rarely used with helmets (unless on track).
Jesus, here Rex is wanking on about shite when he has study to perform.
Live long and prosper, you lot...
Rex
[Updated on: Tue, 16 November 2004 12:25]
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| Subject | Poster | Date |
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Why do people get roll cages?
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andrewa | Mon, 15 November 2004 20:15 |
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Re: Why do people get roll cages?
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muaythaiman | Mon, 15 November 2004 21:01 |
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Re: Why do people get roll cages?
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Purple_Beasty | Mon, 15 November 2004 21:18 |
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Re: Why do people get roll cages?
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Chris Davey | Mon, 15 November 2004 21:29 |
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Re: Why do people get roll cages?
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gianttomato | Mon, 15 November 2004 21:31 |
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Re: Why do people get roll cages?
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Cool1 | Tue, 16 November 2004 07:01 |
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Re: Why do people get roll cages?
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takai | Mon, 15 November 2004 21:34 |
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Re: Why do people get roll cages?
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._T_. | Mon, 15 November 2004 21:50 |
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Re: Why do people get roll cages?
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Purple_Beasty | Mon, 15 November 2004 23:11 |
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Re: Why do people get roll cages?
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._T_. | Tue, 16 November 2004 00:09 |
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Re: Why do people get roll cages?
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bbaacchhyy | Tue, 16 November 2004 07:08 |
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Re: Why do people get roll cages?
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Purple_Beasty | Tue, 16 November 2004 01:04 |
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Re: Why do people get roll cages?
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AE86slut | Tue, 16 November 2004 01:51 |
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Re: Why do people get roll cages?
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DRFTAE86 | Tue, 16 November 2004 12:18 |
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Re: Why do people get roll cages?
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Rex_Kelway | Tue, 16 November 2004 12:22 |
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Re: Why do people get roll cages?
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Kyosho | Fri, 19 November 2004 11:31 |
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Re: Why do people get roll cages?
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takai | Tue, 16 November 2004 12:53 |
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Re: Why do people get roll cages?
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Rex_Kelway | Tue, 16 November 2004 13:27 |
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Re: Why do people get roll cages?
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M.W.P. | Tue, 16 November 2004 15:51 |
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Re: Why do people get roll cages?
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muaythaiman | Fri, 19 November 2004 08:31 |
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Re: Why do people get roll cages?
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ae86drift | Fri, 19 November 2004 11:13 |
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Re: Why do people get roll cages?
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ae86drift | Fri, 19 November 2004 11:58 |
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Re: Why do people get roll cages?
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MS-75 | Fri, 19 November 2004 18:40 |
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Re: Why do people get roll cages?
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greenta22 | Sat, 20 November 2004 07:58 |
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Re: Why do people get roll cages?
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Alchemist | Sat, 20 November 2004 08:41 |
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Re: Why do people get roll cages?
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Purple_Beasty | Sat, 20 November 2004 19:26 |
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Re: Why do people get roll cages?
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ODR-666 | Sat, 20 November 2004 23:10 |