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Re: transfer of momentum/speedos



I remembered the connection was in front, so I searched and found a
"blog" where the blogger knew something was wrong when his speedo went
zero while on the freeway and then sparks flew past his window, and he
saw his wheel * rolling ahead.

* the correct one, left front. I suspect in Brit. it's the right front.

bc

p.s. I just spoke with my mechanic who confirmed the above. He even
added that in some Rabbits this is true tho the connection is into the
transmission (front engine).

Brian Whatcott wrote:

The return spring on the usual analog speedo is often biassed to hold
the pointer gently against the pin stop.

Accordingly, the range from 0-5 mph is often compressed on the scale.
But minor fluctuations in the eddy current drive which can be
distracting at low forward speeds where there is least return torque
do not cause the pointer to bob about so noticeably.

The speedo cable of the mechanical type is always connected to the
transmission, so there is a small reverse loading from the stop on the
pointer during reversing. Because of this mechanical link at the
drive shaft, changes in axle ratio or tire/rim size cause speed
indication errors.

Brian W

At 01:51 PM 11/19/2003, you wrote:


My guess is that analog speedometers are disconnected


from the axle when the transmission is in reverse.


Daniel Crowe
Oklahoma School of Science and Mathematics
Ardmore Regional Center
dcrowe@sotc.org


-----Original Message-----
=46rom: Bernard Cleyet [mailto:anngeorg@PACBELL.NET]
Sent: Wednesday, November 19, 2003 1:36 PM
To: PHYS-L@lists.nau.edu
Subject: Re: transfer of momentum


If one removes the pin, it might read below the zero. Same w/
d'Arsonval meters (usually no pin.)

bc



Hugh Haskell wrote:



At 12:58 -0500 11/19/03, Joseph Bellina wrote:





Here speed is what the car speedometer reads.




And if it's an analog speedometer, when backing up it always reads
zero. But your statement is true for digital speedometers.




Brian Whatcott Altus OK Eureka!