BELT DRIVES AND GEAR TRAINS

A belt drive is a system of pulleys connected by belts.
Each belt connects a pair of pulleys, so they turn together.
A gear train is a system of interconnected gears.
To calculate the ratio transmission between the first wheel and the last of a belt drive, we must multiply the ratios of transmission  of the first pair of wheels and the second pair of wheels:
N4/N1= D1 x D3/ D2 x D4
N is the speed of rotation and D is the diameter of the wheel.
If  is a gear train, we make these calculations using the number of cogs or teeth (Z). Belt drive. Gear train.