h a l f b a k e r y"Look on my works, ye Mighty, and despair!"
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Let's consider currently available methods of vehicle deceleration that are common today. They can be counted on the fingers of one hand: 1. Brake pedal 2. Emergency brake handle/pedal 3. Ignition key in off position. Given that each of those WILL stop your vehicle if operational the only remaining
problem/issue would be stopping distance... Even the best available tires/brakes combinations (save for the chains) can be utterly useless when trying to stop atop of a solid ice sheet or trying to stop in front of the great boulder that you didn't figure would be there despite "Falling Rock" sign you just passed.
But should you despair and prepare for the unavoidable? You don't have to, if your car comes equipped with a EE Brake. The ONLY TRUE emergency brake. How does this miracle product work? And why is it better at stopping your vehicle than the brakes and tires you got on now?
The answer to these question lies in the way the car is stopped using the conventional brakes - FRICTION. Higher friction means faster stopping, right? Therefore, lower friction means a nasty fender bender at the least.
Thus, in order to avoid the accident, friction must be increased. Conventional braking systems, no matter how advanced, CAN NOT offer you greater coefficient of friction "mu" than there exists between the tire rubber and the road. Or should I say COULD NOT until now...
Product Description:
The EE brake itself is made of a steel plate or a series of steel bars (brake body) suspended underneath the car attached to a pivot point (pivot point). Pivot point is facing the front of the car. On the end of the brake body opposite of pivot point there is a series of thick pointed metal spikes (braking spikes)pointing downwards and slightly in the direction of travel.
Above the brake body on the opposite side of braking spikes we have a hydraulic cylinder assembly which, when activated, will lower the end of the brake body with braking spikes on it - rotating it around the pivot point - to the ground. Weight of the car acting on top of the spikes will cause them to dig into the road, thusly bringing the vehicle to a brief halt.
Note:
Pivot point should be located around the mid point of the car with braking spikes being further back in order to avoid spinning around (think anchor).
Question:
What about concrete pavement, spikes will not "dig" into the concrete?
I can't be 100% on this, but I'm almost sure mu of rubber/concrete is lower than mu steel braking spikes/concrete, so even on concrete EE break is more effective. All other types of pavement ice, HMA, dirt, gravel, mud are "digable".
Any more questions?
Emergency stop spike
http://www.halfbake...ency_20stop_20spike
Effectively the same idea. [phoenix, May 29 2002, last modified Oct 04 2004]
The Monty Python Brake Assist System
http://www.halfbake...e_20Assist_20System
The same, save for a rubber foot instead of spikes. [rbl, May 29 2002, last modified Oct 04 2004]
Car Thrust Reversers
http://www.halfbake...0Thrust_20Reversers
A slightly different approach. Some relevant links, as well. [bristolz, May 29 2002, last modified Oct 04 2004]
Car Thrust Reversers II
http://www.halfbake...ust_20Reversers_202
A variation on the variation. [bristolz, May 29 2002, last modified Oct 04 2004]
[clipping link from post by oxygon]
http://www.physlink...skExperts/ae140.cfm
URL link As quoted by oxygons post [oxygon, May 30 2002, last modified Oct 21 2004]
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Don't forget the gear 'PARK' |
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...
4) Downshifting
5) Changing gear to 'reverse' |
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Thanks for getting the catagory right and welcome to the HalfBakery. |
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NTG, have you tried puting a moving vehicle in P? You'll just get a loud clicking as the fail-safe in the transmission kicks in, saving it from destruction. |
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/the great boulder that you didn't figure would be there/ --won't this do the trick? |
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Reverend D: boulder WILL stop the car, however it will also damage/destroy it..... |
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How about this: an emergency break that will stop the car more than ONCE. |
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Phoenix: 4. downshifting doesn't actually stop the car... 5. putting it in reverse is either impossible or explosive :-) and STILL doesn't stop the car, b/c now u r going backwards. |
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Downshifting and then using reverse (which will make a nasty sound, but will not engage until you are *stationary*) does work, and i've had the opportunity to test it, thanks to my brakes cutting out in front of a red light last year. |
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<RWED>/boulder WILL stop the car, however it will also damage/destroy it...../
I do believe that dropping a set of spikes into the road, bringing the vehicle to an immediate halt, will have a similar effect. I'm thinking about the whole Newton's law thing here... What will happen to the body once the frame stops? Shoot, what will happen to MY body once the spike are dropped? After I pick up my 'innards' I think I'll need a good interior detailing. |
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Now add some sort of super restraint system and bolts that won't crack from the pressure and I'll consider this as a definite must. Otherwise...is there an Evil:car:brake section here <G>? |
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Reverend D: touche,
However, there would be no scattering of the innards, or eyeballs popping out because it will not bring you to an IMMEDIATE halt, but instead it will stop you at a greater deceleration rate than comon brakes depending on the surface of the road.
You see, EE brake is meant to be used when nothing else will stop you. The beauty of it is that a reserve brake that has a much higher chance of working than refular brakes. Think of a reserve parachute. Sure it jolts you when it is opened, but would you rather be jolted by it or scrambled by the dirt? |
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Hint: Controlled spin braking. A combination of momentum governing gear that put the car into a spin while maintaining its path forward. In a way, like those thrilling chase scenes that have a pursuit vehicle perform a 180° spin to follow a corrected path. In this case the spin would be slower and longer (maybe 720°) to allow less torque and dispersing the vehicle's forward momentum. Warning -- you'd see a lot of that from risk-taking drivers. |
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The EE brake spikes could be made of hardened tungsten or similar material so that they will in fact dig into concrete. |
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Good choice for working title. 'Eeeeeeeeeeeeeeeee!' typically precedes most circumstances where this would come in handy.
6) have hydraulic cylinder drop REALLY fast a la Speed Racer. You won't stop, but you may still avoid the obstacle.
7) have an old-fashioned ship anchor on hand to throw out. |
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//...using reverse (which will make a nasty sound, but will not engage until you are *stationary*)...//
Not necessarily. My car has synchromesh on reverse. |
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Really? As I understand it, angel, that's pretty rare - But I bet it'd still make a gawdawful noise if you tried to do it while the car was going forward, synchromesh or not... |
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Yeah, it's for use at parking speeds only. Not sure how rare it is, though. I drive a '92 Carlton, which isn't that uncommon. |
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Big airbrakes also worked on Mercedes Le Mans cars in the 'fifties. |
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I may be worrying over nothing, but all that steel scraping over a tarmac or concrete road surface is going to give you a hell of a lot of sparks. |
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11. Jettison all four wheels.
12. Jettison driver. |
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If it's a car, and it needs to be stopped pretty fast, the obstacle is on the ground, right? 13. Deploy fast erecting microlight wings and lift driver and passengers clear of danger. |
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You will have to be careful where you choose to land, but that is a fish of a different pickle all together. |
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At least he didn't call it XE brakes like what is so common now in US nameing conventions. |
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[clipping]
Question
Why doesn't friction depend on surface area? |
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Answer:
Although a larger area of contact between two surfaces
would create a larger source of frictional forces, it also
reduces the pressure between the two surfaces for a
given force holding them together. Since pressure equals
force divided by the area of contact, it works out that
the increase in friction generating area is exactly offset
by the reduction in pressure; the resulting frictional
forces, then, are dependent only on the frictional
coefficient of the materials and the FORCE holding them
together.
If you were to increase the force as you increased the
area to keep PRESSURE the same, then increasing the
area WOULD increase the frictional force between the
two surfaces. |
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Answered by: Paul Walorski, B.A. Physics, Part-time
Physics Instructor
[/clipping] |
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14. Reverse thrust supplied by rockets. Essentially instant light-up is possible, with the added benefit that when you stop, the offending obstacle has probably been torched anyway, allowing a dignified continuation of the journey, waving to the open-mouthed, brown-trousered bystanders. |
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There are circumstances where a super-emergency brake might be useful. Unfortunately, a brake which might be very useful in snow could be destructively bad on a bumpy concrete road. Given a choice between having a vehicle crash and having a major road closed down for a couple days for repairs, many highway departments would prefer the former. |
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The only thing I can think of that might be good would be to squirt some rubbery goop in front of the tires. That could probably improve stopping distance, but it would make a big mess, and would severely degrade the fuel economy of any vehicle that ran into the goop on the road. |
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// waving to the open-mouthed, brown-trousered bystanders // |
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This particular driver will also share their brown-trouseredness. |
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for some reason I get a picture of the spikes catching hard on one side and sending the car into that boulder top first rather than bumper first as it spins flips and rolls its way to a rest. |
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