Big Brakes

[Helge Wunderlich]

On Tue, 04 Sep 2001 10:02:16 -0700, Bob wrote:

>Vehicle weight.....
>If I had a 10,000 lb car with 10hp, youre saying the brakes would be smaller
>than a 100lb car with 100hp?

I did not say engine power was the *only* factor, I said it was the
*most important* factor.

The brakes need to be large enough for a stop from top speed, and if
the engine is powerful enough to bring the speed up quicker than the
brakes cool down, you need even bigger brakes.

Your unrealistic examples cause the factors that are normally
insignificant to become a problem. One of these is downhill driving.

The heavy 10 HP car would have a top speed of 50 km/h or so, and would
therefore need almost no brakes at all. Gaining speed would take so
long that the brakes would have plenty of time to cool down. The
problem would be downhill driving, but any car with a realistic power
to weight ratio will have big enough brakes for sensible downhill
driving.

The very light car would only need small brakes for casual street
driving, but since the engine is able to accelerate the car to
incredible speeds in seconds, the brakes don't get much chance to cool
between each use, the brakes would have to be big, but they would also
have to be very well cooled to get rid of all that power delivered by
the engine.