From: "Jerry Herrman" <[email protected]>
With your collective indulgence, I'd like to re-open the discussion of the
topic "sudden acceleration". You may recall in mid february I opened the
discussion with this submission in vol. 51 issue 39, or thereabouts:
( " So yesterday I heard what I believe was a public service announcement
(by some automotive engineer, I think) on the radio saying that the
least powerful brakes are going to easily overpower the most powerful
engine.This suggests that applying your brakes firmly in an unexpected
acceleration situation would prevent a catastrophe.")
Responses from subscribers to this forum suggested that applying the
brakes firmly and immediately to stop the car would be successful,
regardless of the power output of the engine. Applying the brakes to
merely slow down the vehicle, most concluded, would likely result in
overheating the brakes to the point that they could be ineffective.
The recent report of a Prius driver's scary struggle with sudden
unexpected acceleration raises this topic again.
I am taking no position on this issue. I am asking questions to better
understand what is happening.
Here are several questions that circulate through my mind.
If a driver were to experience this phenomenon in a powerful car whose
speed has gone well above 100 mph, would there be any hope of stopping the
car using only the brakes?
Can a Prius whose driver is trying to brake the car continue to
accelerate? How powerful is the Prius engine?
Can all cars be shifted easily into neutral in the event of this
emergency?
Is there any "down side" to turning off the engine in this situation?
Having driven a 240D for many years, sudden acceleration sounded rather
attractive . Now, not so much.
Jerry
1982 240D 60+ horsepower
--------------------------------------------------
During the 1980s I asked a trucker about the best way to use brakes on a
long mountain grade with a heavy loaded pickup pulling a heavy trailer with
no brakes. He said once you start down the grade apply the brakes gently
and don't let off until the bottom of the hill. He said that the brake
linings outgas, and when you let off and then reapply the brakes there is a
layer of gas between the brake and the disc or shoe that severely reduces
the efficient of the brakes.
He also said that if you have to apply close to half braking force, you
should then apply full force and stop on the side of road. You should let
the brakes cool down for ten or fifteen minutes and then start down the hill
in a lower gear with minimal braking pressure; never letting off the brake
until the bottom of the hill.
This would tell us that if a Prius engine ran away with itself, the driver
should apply full braking pressure at the first hint of a runaway, never
releasing full pressure, pull over, and never take his/her foot off the
brake until he/she got the engine to stop.
It's easy to tell people not to buy Toyotas, but there is already a large
base of Toyotas on the road and many owners have no choice but to keep
driving them.
Yesterday I pulled up in the local Toyota dealers lot to see how his
business was doing. There were salesmen doing deals in their cubicles with
buyers, and others demonstrating various models to prospects. Business
seemed to be pretty good
Gerry Archer
'83 300D and 240D
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