Gas Pedals are Complicated

[Philip Miller Tate]

Huh, who needs all this technodgery? The old British Leyland 'B'  
series engine was designed with a throttle spring set such that if  
the throttle cable snapped, the throttle was physically pulled wide  
open. It's sobering how few people thought to turn off the ignition  
key when they suddenly found that their throttle pedal had gone slack  
and that they were accelerating to maximum speed without control, nor  
even disengaging gear before applying the brake. Of course, in those  
days, turning off the engine did not lead to a steering lock  
preventing steering.

One of many things I like about my Subaru Legacy Outback is the way  
that the manual is full of things like, "If the transmission locks up  
and the selector refuses to move, lever off cover 'A' with a large  
screwdriver, jam the screwdriver into hole 'B' with all your might,  
and drive to your dealer within a month or so to get it looked at."  
It is full of "yes-it's-failed-but-this'll-get-you-home" options.

Phil M1GWZ




On 28 Jan 2010, at 22:44, Mark Whittington wrote:

> On Thu, Jan 28, 2010 at 5:32 PM, Robert Stratton  
> <robert.stratton at stratton.net> wrote:
>
> I not long ago exercised a leap of faith and bought a car that is  
> brake-by+wire. The safety benefit from it is that if I rapidly take  
> my foot off of the accelerator, it pre-positions the brake pads  
> closer to the disc to minimize actuation time. I continue to have  
> low-level anxiety about just how many if the code paths actually  
> were exercised during regression testing.
>
> No, no and no.  Brakes are one of the few things that I refuse to  
> delegate to computers.  No amount of pre-positioned anything is  
> ever going to convince me that losing a direct physical linkage  
> between my foot, the brake pedal and the brakes on the wheel is  
> worth it.  There are just too many potential failure modes there  
> for me to ever actually be comfortable with that.
>
> Good luck!
>
> Also, "Hi, everybody!"
>
> -Mark
> KA8I
>
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