According to the national standard, V has seven kinds of O, A, B, C, D, E and F, and pulley groove angles are 34, 36 and 38. At the same time, the minimum diameter of the small pulley corresponding to each groove angle of each type of V belt is also specified, but the large pulley is not specified. The groove angle of pulley is divided into 34 degrees, 36 degrees and 38 degrees, and the specific selection should be based on the groove type and reference diameter of pulley; The groove angle of the pulley is related to the diameter of the pulley. The recommended number of groove angles of different types of pulleys in different diameter ranges is as follows: when the pulley diameter is in the range of 50mm-7 1mm, the O-type pulley is 34 degrees; 71mm ~ 36 degrees at 90 mm, and > 38 degrees at 90 mm; Type A pulley is 34 degrees in the range of pulley diameter from 7 1mm to 100mm, and 36 degrees in the range of pulley diameter from 100mm to 125mm; & gt/kloc-38 degrees at 0/25mm; Type B pulley is 34 degrees when the pulley diameter ranges from 125mm to 160mm; /kloc-36 degrees when it is 0/60mm ~ 200 mm, and 38 degrees when it is more than 200mm; Type c pulley is 34 degrees when the pulley diameter is 200mm ~ 250mm, 36 degrees when the pulley diameter is 250mm ~ 3 15 mm, and > 38 degrees at 3 15mm; The diameter of D-type pulley is 36 degrees when it is 355 mm to 450 mm, and > 38 degrees when it is 450 mm; E-type 500 mm ~ 630 mm is 36 degrees, and 630 mm is > 38 degrees.