| Re: Why can't car speedos be accurate? |
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Group: uk.transport · Group Profile
Author: PetertPetert Date: Sep 20, 2008 04:39
On Mon, 15 Sep 2008 05:29:39 -0700 (PDT), Boltar
yahoo.co.uk> wrote:
>Since truck, bus and train speedos can be accurate why can't they do
>the same for cars? It can't be hard in these days of electronic
>everything to have some optical revolution counter on an axle so whats
>the problem? I drove past one of these flash you speed up signs the
>other day and while my speedo said 38 the sign said 34 so thats a good
>percentage out. And my tyres and new and inflated to the correct
>pressure so they're not the culprit. So why don't car manufacturers
>bother?
>
>B2003
I suppose one reason is that the radius, or rather, the circumference
of the wheels of cars/lorries etc aren't constant. It will change as
the tyre wears down and as the pressure of the air inside it
expands/contracts/leaks.
Perhaps a different means of measuring the speed of a vehicle is
needed - perhaps some sort of radar signal bounced off the road below
the vehicle?
--
Only some ghastly, dehumanised moron would want to get rid of the Routemaster.
Ken Livingstone 2001.
PeterT - "Reply to" address is a spam trap - all replies to the group please
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