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Thread: safety design query curious

  1. #1
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    Default safety design query curious

    Although I understand the design of the Mercedes A class W169 was to enable it to be electric I have also read another claim. It is supposed to be a safety factor if unfortunate enough to be in a head on collision : your engine will not come through. However, does having the engine in front of you provide more protection in the event of a crash ?
    I would welcome some collective wisdom on this - thanks.

  2. #2
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    I am not an engineer.

    The emphasis these days is on energy absorbing 'crumple' zones. If you ever see the aftermath of a collision, you will notice that the bodywork is likely to be severely damaged. However, even when a car is a total write off, the driver and passengers escape with cuts and bruises. The cuts from all the broken glass, and the bruises from the seat belt and the air bag.

    Having a big lump of metal in front may or may not be a good thing. It could stop anything from getting past, but it could, itself, be pushed back into the passenger compartment, potentially crushing legs and feet.

    In any case, all new designs have to pass extensive tests before they are permitted to be sold. One advantage of the EU I suppose.

  3. #3
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    I would think that, once the engine of a car in a head-on collision had come to a final stop against the 'obstruction', the ongoing crumpling of the vehicle would then result in the engine entering the passenger compartment. It is possible that, without the engine (and thus its additional weight), the force of the front end would decay more quickly, and the space resulting from the absence of the engine might provide more scope for significant improvements in a crumple zone that gave more gradual collapse of the vehicle and more time for the forces to decay before the passenger compartment came under threat.
    My only concern about a much lower weight at the front end is the loss of that weight to help reduce the skid factor. I once had a car with a rear engine (many years ago) and it skidded on an icy road. The resulting impact on a car in front, although slight, would probably not occurred with a conventional front engine. Since that time I have always avoided rear-engine cars. This may not be such a problem with modern cars, but I still prefer to follow my own instincts.

  4. #4
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    Smart cars are designed in such a way, that the engine gets puts under the car, in case of a head on collision. I saw some film clips on U/tube, where other small cars, were crashed, by being driven into a concrete wall, and the Smart came out tops.

  5. #5
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    Quote Originally Posted by smudger View Post
    Smart cars are designed in such a way, that the engine gets puts under the car, in case of a head on collision. I saw some film clips on U/tube, where other small cars, were crashed, by being driven into a concrete wall, and the Smart came out tops.
    That doesn't surprise me, smudger. When a vehicle goes head-on into something solid, there is a lot less weight in a smart car than the more conventional ones, so less weight towards the back end to keep up the pressure on the collapsing vehicle shell.

  6. #6
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    I imagine that the heaviest thing in a Smart car is probably the driver.

  7. #7
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    Having the engine mounted low under the passenger compartment means it is unlikely to enter the passenger compartment in a severe crash. You wont have a red hot lump of metal weighing 2 or 3 hundred pounds squashing your legs. Hopefully...

  8. #8
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    Thank you. I really appreciate these helpful replies. For someone with my limited knowledge they are especially valuable.

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