ABS and Airbags

Thanks Dan!

 

OT:

I don't remember if I've asked this already so here goes! What would happen if say I was going 70 and I accidentally hit the power button? Just curious.

 

Ah.

 

hmmm. maybe nothing.

try it sometime. it may just beep at you since the Prius usually wont allow you to do anything that would hurt the system.

 

I'm too chicken to try it.

I have another question while I have your attention. I need a paint pen to touch up some areas on my hood. Should I purchase this through Toyota at the local dealership? Is this something they should have in store?

 

i would guess that if the car did shut down, it would maintain power to steering and brakes until it sensed the car had stopped.

in normal operation, most of the gears dont work if it is sensed the car is moving.

my guess is that if it did anything by hitting the power button, it would just shift into neutral.

it most likely wont do anything until you stop the vehicle.

 

My local didn't even have that in my color, they had to order it. I needed the brush one anyway. The door edge guard installation required removing a little strip of painted 'gasket', then painting the exposed edge. I don't think the pen type would have done the job. OTOH, if I had a little ding, it would certainly be preferable to the brush.

 

You can shut down the car in an emergency by holding the power button for over 3 seconds. Not sure how OFF that would go (as in PS, brakes, etc).
Might be why some people have been able to get out of what seems a stuck-on mode.

 

i know there is a speed lockout that won't let you turn off the car above a near stop, if you do it will go neutral.

what would happen if you held the button for emergency shutdown (ie 3 sec hold) while the car was above the cutoff speed?

would someone mind doing a small 10 mph experement in a large parking lot?

 

I second or third the B.S. response. I have been involved in the design and development of ABS for over 17 years. I have driven hundreds of cars and trucks, and done probably a million plus ABS stops on every surface you can imagine. These have been development, validation, and production vehicles. I have NEVER had an air bag deploy as a result of ABS activity. There is no way to generate the G-forces needed to activate the air bag impact sensor, which requires several G's. A typical ABS stop can approach 1 G, however a few high end sports cars can generate a bit more than 1 G during the stop. If there are any isolated cases out there, they are just that, isolated, and the result of some defect or design screw-up.

 

FYI, unless I am misinterpreting your re , this is not correct. A rotating tire, with a small amount of slip, has more traction, a higher coefficient of friction, than a locked wheel. Technically, a locked wheel is hydroplaning on the rubber. Go back to physics. A wood block is placed on an inclined surface. The block remains at rest. Push the block. The block slides down the incline because the sliding friction is less than the resting friction. While this is not a direct comparison, there is a friction curve for an object which shows its frictional capability for various amounts of slip, including zero slip. Rubber offers a higher friction at about 10% slip versus zero slip or high slip. An ABS equipped vehicle, calibrated correctly, will reduce stopping distances on dry concrete or asphalt by about 10% above a skilled driver who does not lock the wheel. Locked wheel stops are often 10 to 20% longer. On wet roads, the stopping distance is about the same as a skilled driver could accomplish without locking the wheels. Locking the wheels results in hydroplaning, which increases stopping distance. Note you can also still steer the vehicle under these conditions. On deformable surfaces, such as sand, snow, or gravel, ABS stopping distances are generally about 15% longer to preserve directional stability and allow for some steering during braking, a result of not allowing the tire to dig into the surface.

Leaving a flat spot on you tire does nothing but ruin the tire. If the quoted statement were true, the objective of brake system design would be to lock the wheels to minimize stopping distances in emergency situations. This is not the case. High ABS efficiency leads to the shortest stopping distances, and is a measure of how much time the wheel is maintained at the ideal slip level, about 10 - 15%.