[Mgs] Mgs Digest, Vol 195, Issue 1

[Paul Hunt]

Both those are describing the function of the instrument which is the 
same in both cases and is not the point in question.  Even so the first 
definition includes the statement "In formal engineering nomenclature, 
more precise terms are used to distinguish the two.".

The PO's question was how do I connect a _tachometer_ , and the answer 
to that is fundamentally different to a rev counter.  A rev counter 
displays the rate at which a cable drive is turning, a tachometer 
measures the time between successive electrical pulses.  In the rev 
counter case it doesn't matter whether it is on a 4, 6 or 8 (etc.) 
cylinder whereas for a tachometer the pulses from an 8 cylinder engine 
are coming in at twice the rate of a 4-cylinder and there have to be 
_internal_ differences in the tachometer to display that correctly.  If 
the terms are used interchangeably then when responding to a (formal 
engineering?) question you would first have to establish which one is 
being talked about!

PaulH.

On 02/08/2023 14:29, dave northrup wrote:
>
> From Wikipedia
>
> A *tachometer* (*revolution-counter*, *tach*, *rev-counter*, *RPM 
> gauge*) is an instrument measuring the rotation speed of a shaft 
> <https://en.wikipedia.org/wiki/Axle> or disk, as in a motor or other 
> machine.^[1] <https://en.wikipedia.org/wiki/Tachometer#cite_note-1> 
>  The device usually displays the revolutions per minute 
> <https://en.wikipedia.org/wiki/Revolutions_per_minute> (RPM) on a 
> calibrated analogue dial, but digital displays are increasingly common.
>
> The word comes from Greek 
> <https://en.wikipedia.org/wiki/Greek_language> τάχος (/táchos/ "speed") 
> and μέτρον (/métron/ "measure"). Essentially the words tachometer and 
> speedometer <https://en.wikipedia.org/wiki/Speedometer> have identical 
> meaning: a device that measures speed. It is by arbitrary convention 
> that in the automotive world one is used for engine revolutions and 
> the other for vehicle speed. In formal engineering nomenclature, more 
> precise terms are used to distinguish the two.
>
> From dictionary.com
>
> *tachometer*
>
> [ ta-*kom*-i-ter, t/uh/- ]SHOW IPA
>
> ------------------------------------------------------------------------
>
> /noun/
>
>  1. any of various instruments for measuring or indicating velocity or
>     speed, as of a machine, a river, or the blood.
>  2. an instrument measuring revolutions per minute, as of an engine.
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/mgs/attachments/20230803/6464fcd7/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 177 bytes
Desc: not available
URL: <http://autox.team.net/pipermail/mgs/attachments/20230803/6464fcd7/attachment.png>