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|
| > > ????????????? how ???????????
| > > one turn of a sticky cable is still one turn.
| > > A sticky cable can cause a speedo to "bounce"
| > > but the cable will not turn faster.
|
| What may happen is that the binding cable will cause cycles of fast and
| slow revs, as the cable twists enough to overcome whatever is binding it.
| While this may cause the needle to bounce, if the frequency is correct it
| can result it a higher reading, due to the speedos tendency to "average"
| out the bounces. If you think about it, that is how a speedometer works,
| the spinning cable causes pulses on the needle that are counter-acted by
| a spring pulling the needle back.
|
"if you think about it" the average of the high speed and low speed should
come out to a just about right speed, certainly not 25% high anyway.
(unless you invent a cable that goes 3 turns a second at one end and 4 turns
a second at the other.) Big trucks that use two speed axels sone times use a
solonoid operated two speed planitary gear set in the speedo cable. I used
one of those about thirty years ago to get the speedo correction right, after
a fairly strange engine swap.
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