The shaft of the car engine transmits power to the gearbox, and the transmission ratio from the output shaft of the gearbox to the wheels is constant.
The output shaft of the gearbox is fitted with a "soft shaft" that goes straight to the speedometer in front of the driver. The so-called "soft shaft" is a spiral tube
with a steel wire core like the pull wire used in the bicycle brake. There is lubricating oil between the tube wall and the inner core, and the outer tube is fixed and the
inner core can rotate. The speed of the inner core has a constant proportional relationship with the speed of the wheel. The flexible shaft is connected to the
speedometer so that the pointer indicates the speed of the car. At the same time, by soft shaft rotation of worm and worm wheel to speed table in the middle of the roller on the counter,
turn the wheels of the number represented by the mileage accumulated down, because of the speed and distance are all on the same root of flexible shaft rotation driven,
so these two tables together, the former use pointer instructions, the latter by roller counter cumulative.
[VIP第7年] 指數(shù):7
通過認證 
