Belt pulley is a kind of disc hub part with relatively large relative size, and its manufacturing process is generally mainly casting and forging. Generally, the larger size is designed by casting method, and the material is generally cast iron (with good casting performance), but rarely cast steel (with poor casting performance of steel); Generally, the smaller size can be designed for forging, and the material is steel. Pulleys are mainly used for long-distance transmission of power, such as the output of small diesel engines, agricultural vehicles, tractors, automobiles, mining machinery, mechanical processing equipment, textile machinery, packaging machinery, lathes, forging beds, transmission of power of some small horsepower motorcycles, transmission of power of agricultural machinery, air compressors, reducers, reducers, generators, ginning machines, etc.

The advantages of pulley transmission are: the pulley transmits kinetic energy to mitigate load impact; The belt pulley drives stably, with low noise and vibration; The structure of belt pulley drive is simple and easy to adjust; The manufacturing and installation accuracy of pulley drive is not as strict as that of meshing drive; The belt pulley drive has the function of overload protection; The adjustment range of the center distance between the two shafts of the belt pulley drive is large. The disadvantages of belt transmission are: the belt pulley transmission has elastic sliding and slipping, the transmission efficiency is low and the accurate transmission ratio cannot be maintained; When the belt pulley transmission transmits the same circumferential force, the profile size and shaft pressure are larger than those of the meshing transmission; The pulley drive belt has a short life. The pulley diameter and other dimensions of various mechanical equipment are all their own

It is matched according to the reduction ratio, and designed according to the working speed and motor speed. Working speed/motor speed=driving pulley diameter/driven pulley diameter * 0.98 (slip coefficient). If steel pulley is used, 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; conversion ratio of motor speed to pulley diameter, speed ratio=output speed: input speed=load pulley pitch diameter: motor pulley pitch diameter. The pitch circle diameter is the same as the reference diameter. Diameter-2h=pitch circle 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. The pitch circle diameter of the pulley is the theoretical diameter of the pitch line position of the pulley, somewhat like the indexing circle diameter of a gear. It is generally expressed in PD, and the outer circle is generally expressed in OD The conversion formulas of pitch circle and excircle of different groove types are different. Generally, we can easily measure the excircle of the pulley, and then 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 A or SPA pulley is 80mm. If it is smaller than this size, especially at high speed, the belt is prone to delamination and cracks at the bottom. SPZ belt, small wheels no less than 63mm. At the same time, pay attention to the installation method and tension of the belt. Too small is easy to slip, and too large is easy to damage the belt and bearings.