The advantages of pulley transmission are:

pulley transmission can alleviate load impact;

pulley transmission runs smoothly, with low noise and vibration;

pulley transmission has a simple structure and is easy to adjust;

pulley transmission is not as strict as meshing transmission in terms of manufacturing and installation accuracy;

pulley transmission has overload protection function; pulley transmission has a large adjustment range of the two-axis center distance.

The disadvantages of belt transmission are:

pulley transmission has elastic sliding and slipping, low transmission efficiency and cannot maintain an accurate transmission ratio;

when pulley transmission transmits the same large circumferential force, the outline size and shaft pressure are larger than meshing transmission;

the life of the pulley transmission belt is shorter.

The diameter and other dimensions of the pulleys of various mechanical equipment are matched by themselves according to the reduction ratio, and are designed by themselves according to the working speed and the speed of the motor. Working speed/motor speed = driving wheel diameter/driven wheel diameter*0.98 (slip coefficient).

If the pulley is made of steel, the linear speed is required to be no higher than 40m/s.

If cast iron is used, the linear speed is required to be no higher than 35m/s. The motor speed and pulley diameter conversion ratio, speed ratio = output speed: input speed = load pulley pitch diameter: motor pulley pitch diameter. The pitch diameter is the same as the reference diameter, diameter-2h=pitch diameter, h is the groove depth on the reference line, different types of V-belts h are different, Y Z A B C D E, the groove depth on the reference line is h=1.6 2 2.75 3.5 4.8 8.1 9.6 respectively. The pitch diameter of the pulley is the theoretical diameter of the pitch line position of the pulley, which is a bit like the pitch circle diameter of the gear. It is generally represented by PD, and the outer circle is generally represented by OD. The conversion formulas for different groove types are different. Generally, it is easier for us to measure the outer circle of the pulley and calculate the pitch circle according to the formula. SPZ: OD=PD+4; SPA: OD=PD+5.5; SPB: OD=PD+7; SPC: OD=PD+9.6. The minimum outer diameter of the pulley of A or SPA is 80mm. If it is smaller than this size, especially at high speeds, the belt is prone to delamination and cracks at the bottom. For SPZ belts, the small wheel should not be less than 63mm. At the same time, pay attention to the installation method and tension of the belt. If it is too small, it is easy to slip, and if it is too large, it is easy to damage the belt and bearings.