can anyone explain how a mechanical speedometer works.?

Answer 1

The speedometer is made up of two sections, the odometer which records the miles and the speed indicator. The odometer is quite simple, a simple gear train which takes a given number of turns of a tire and gears those turns down to equal one turn of the tenths wheel. Simple gearing. The speed needle is quite different. It works on magnetic fields. Connected to the cable is a magnet on the very end, usually in the sape of a disc. Close to, but not touching, is an aluminum disc. The magnet spins and genenerates eddy currents in the aluminum disc which produces a magnetic field in the disc, which tends to drag the aluminum disc to spin with the spinning magnet. There is a spring which works against the movement of the needle. So, the faster the magnet spins, the more the aluminum disc tends to be dragged along, resisted by the spring. So, the faster the spin, the higher the needle reads. In essence, it is a rate meter, which indicates the rate the magnet is spinning.

There is a second kind, one which uses an actual meter movement, just like an old fashioned volt meter, which is a coil in a magnetic field. Current through the coil makes the needle move. In the 2nd kind, the thing hooked to the driveshaft or transmission is actually a small generator which makes a voltage proportional to speed, which makes the needle move appropriately. The odometer still works the same, a simple gear reduction from some spinning point in the drive train.

By the way, in My VW Microbus, the speedometer cable threads from the dashboard to the hub of the left front wheel. Not all speedometers work off a gear in the transmission.

Answer 2

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RE:
can anyone explain how a mechanical speedometer works.?

Answer 3

Coming out of your tranny is a square cable inside a woven metal tube .in your tranny a gear rides on a nother gear that will turn when you drive forward. The other side is screwed behind your speedometer on your dash. All has to be geared properly like a watch. If you put big rims on you car chances are you need to regear speedomitter

Answer 4

it has a long thin cable that is inside a flexible tube goes from the speedometer head to a generator on the transmission ,the generator has gears in it that reduces the speed of the cable that spins and turns the speedometer head

Answer 5

the transmission has a gear that turns a cable that goes into the speedometer which is directly driven, there are different gears for different size tires that go into the transmission.

Answer 6

gears, many teeth meshing. turn turn turn