A speedometer is used to measure the speed of a vehicle and the odometer is used to measure the distance traveled.What is the mechanical relation with respect to the wires etc inside an automobile with respect to the speedometer and the odometer?moreover in most of the vehicles the odometer is incorporated inside or just beside a speedometer. Why?when we talk of the servicing of a vehicle can we use the word speedometer to describe the kilometer head or an odometer?

Not sure I get your question.

The odometer and speedometer are 2 different units. Most are driven by the same sensor in the transmission (VSS). On most cars, the head units are together but are referred to separately.

odinn7 is correct - both the speedomeer and odometer are driven by the same sensor, which senses the rotation of the drive shaft. The odomter simply counts the numberof turns of the drive shaft, multiplies that by a factor that acounts for the gearing of the differential and diameter of the car's tires to determine the equivalent distance traveled. The speedometer counts revs per minute of the draft shaft and multiplies by a factor to convert to MPH (opr KPH). In the old days there was a mechanical flexible drive cable that ran from the drive shaft to the ododmeter/speedometer cluster - the cable had an internal flexible spline that rotated with the drive shaft and drove mechanical gearing inside the speedometer & odometer to make them operate; hence the two gauges were built inside a single unit. With more modern electronic sensors and displays there is no lmiitation to have both speedometer and odometer gauges colocated, except that for ergonomic reasons automoble designers like to cluster the most important gauges directly in front of the driver.