Belt wheel drive can ease the load impact pulley drive stable running, low noise, low vibration; pulley transmission is simple in structure, convenient adjustment; of for pulley pulley transmission manufacturing and precision unlike transmission installation in strict; pulley drive with overload protection function; two pulley drive shaft Center distance adjustment range. Disadvantages of belt drive: belt transfer elastic slip and slip, transmission efficiency is low and it is not kept accurate ratio; passing pulley drive force is equal to the circumference, contour dimensions of axial pressure ratio and transmission; pulley drive belt service life was short. The diameter of the pulleys of all types of machinery and equipment according to the gear ratio with their own size, according to the working speed and the rotational speed of the motor design. Work speed/motor speed = active round diameter/from gear diameter *0.98 (sliding coefficient), as using steel for material of belt round, requirements line speed not above 40m/s, as using cast iron of material, requirements line speed not above 35m/s, motor speed and belt round diameter conversion than, speed than = output speed: entered speed = load belt round section round diameter: motor belt round section round diameter. Diameter of pitch circle diameter and the base is the same as the diameter -2H= diameter of the pitch circle, h is a Groove on the baseline, different models of v-h is not the same as y z a b c d e, deep on the baseline h=1.6 2 2.75 3.5 4.8 8.1 9.6, respectively. Pulley pitch diameter is the diameter of the pulley line theory, sort of like the diameter of the pitch circle of the gear. PD, cylindrical OD. different Groove sections of circular cylindrical conversion formulas are not the same, we are relatively easy to measure out of the pulley, calculated according to the formula out of the pitch circle. SPZ:OD=PD+4; SPA:OD=PD+5.5; SPB:OD=PD+7; SPC:OD=PD+9.6。 A minimum outside diameter of the pulley dimensions or SPA is 80mm, if less than this size, especially in the case of high speed, belt prone to stratification and bottom crack problems. SPZ ferry not less than 63mm. Also note that belt installation methods and the tension, too small and easy to slip and damage the belt and bearings.