2006-07-20 07:14:52 · 6 answers · asked by Walman 1 in Cars & Transportation ➔ Maintenance & Repairs
Actually they typically measure the output shaft turns to the Drive shaft. A sensor in the transmission gives a pulse to the speedo every time the shaft has moved one revolution. The pulses are totaled for quantity and divided by the by the rear differential/tire size ratio to determine distance traveled. The instantaneous speed is calculated by using the same pulses and ratios and dividing by the time between pulses. That is then displayed on the Speedo's indicator. Digital or analog as the case for your car.
http://auto.howstuffworks.com/odometer2.htm
Simple.
Yours: Grumpy
2006-07-20 07:18:51 · answer #1 · answered by Grumpy 6 · 1⤊ 0⤋
I'm sure somebody will dispute this, but I'm pretty sure late model cars, especially those with digital speedometers work off a sensor on the distributor. Obviously changing wheel or tire size will make the reading inacurate but it would do the same thing with the "old" types that ran a cable from the transmission tail shaft to the back of the speedometer. They are all calibrated for Factory wheels and tires.
2006-07-20 07:22:13 · answer #2 · answered by Bullfrog_53 3 · 0⤊ 0⤋
9 times out of 10 it's in the tail shaft housing of the transmission
2006-07-20 07:20:25 · answer #3 · answered by Gary Gearfreak 3 · 1⤊ 0⤋
other...its usually a gear driven off of the transmission...but its in a ratio...its not actual output rpm of the driveshaft or axle...the gears can even be changed to calibrate for varying wheelsizes/final drive ratios ...alot of newer ones are electronic sensors so i would imagine theres a way to calibrate them with the computer...i may be wrong on that.
..it couldnt be the distributer only..in first gear at 3000rpm would be a low speed and 4th att 3000 would be a highspeed....so it would have to be a combination of sensors...or simply one on the output of the tranny that can be calibrated for different ratios and wheelsizes.
2006-07-20 07:21:06 · answer #4 · answered by Anonymous · 1⤊ 0⤋
You have to calibrate it with the diameter of the wheel, and then it measures the wheel rotation and converts it to mph and km/h.
2006-07-20 07:19:07 · answer #5 · answered by Will L 2 · 0⤊ 0⤋
Hypothetically of direction, in the event that all of them confronted West it may velocity up, and in the event that all of them confronted East, it may decelerate. of direction with the mass of the Earth whilst in comparison with the mass of each and every of the vehicles, you nonetheless does no longer be able to degree the version. And as quickly as each and every of the vehicles stopped, the rotation could bypass precise lower back to customary. this finished component could take place as a results of fact of Newton's third regulation. (for each action there is an equivalent and opposite reaction.)
2016-12-10 11:08:47 · answer #6 · answered by beisler 3 · 0⤊ 0⤋