Transmission belts can be divided into V-belts and synchronous belts (toothed belts and synchronous belts) \ r \ n \ r \ nThe belts are classified according to their back width (top width) and height (thickness). According to the different sizes of back width (top width) and height (thickness), the national standard stipulates O, A, B, C and C of V-belt. These different groove types determine the pulley types such as O-type pulley, A-type pulley, B-type pulley, C-type pulley, D-type pulley and E-type pulley. The models of V-belts are: ordinary O A B C D E 3V 5V 8V, ordinary reinforced AX BX CX DX EX 3VX 5VX 8VX, narrow V-belt SPZ SPA SPB SPC, strong narrow V-belt XPA XP B XP C；; Each type of V-belt specifies the cross-sectional size of the V-belt. The cross-sectional dimensions of A-type V-belt are: top width 13mm, thickness 8 mm; The cross-sectional dimensions of type B V belt are: top width 17MM, thickness10.5 mm; ; The cross-sectional dimensions of C-V belt are: top width 22MM, thickness13.5mm; ; The cross-sectional dimensions of the D-shaped V-belt are: the top width is 2 1.5MM and the thickness is19 mm; ; The cross-sectional dimensions of the E-shaped V-belt are: the top width is 38 mm and the thickness is 25.5 mm. Corresponding dimensions (width * height): O( 10*6), A( 12.5*9), B (16.5 */kloc- 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, it also stipulates the minimum diameter of the small pulley corresponding to each groove angle of each type of V-belt, not the large pulley. The groove angle of pulley is divided into 32 degrees, 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 0/60 mm ~ 200 mm, and 38 degrees when it is more than 200 mm; 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 the position at 630 mm is more than 38 degrees \ r \ n \ r \ There are two types of synchronous belt teeth: trapezoidal teeth and arc teeth, and there are three types of arc teeth: arc teeth (H series is also called HTD belt), flat-topped arc teeth (S series is also called STPD belt) and concave-topped parabolic teeth (R series). \r\n Ladder-toothed synchronous belts Ladder-toothed synchronous belts are divided into single-sided toothed belts and double-sided toothed belts, which are referred to as single-sided belts and double-sided belts for short. Double-sided tape can be divided into symmetrical tooth type (code DA) and staggered tooth type (code DB) according to the arrangement of teeth. The trapezoidal tooth synchronous belt has two size systems: pitch system and modulus system. China adopts pitch system, and the corresponding standards of synchronous belt drive GB/T/KOOC-0//KOOC-0/36/KOOC-0/362-/KOOC-0/989 and GB/T/KOOC-0//KOOC-0/665438 refer to ISO. \ r \ nArc-toothed synchronous belt has basically the same structure as trapezoid-toothed synchronous belt except that its tooth profile is curved, and its belt spacing is equivalent, and its tooth height, tooth root thickness and fillet radius are larger than trapezoid-toothed synchronous belt. The stress distribution of the teeth after stress is good, which relieves the stress concentration at the root of the teeth and improves the bearing capacity of the teeth. Therefore, the arc tooth synchronous belt transmits more power than the trapezoidal tooth synchronous belt, and can prevent the interference of teeth in the meshing process. Arc-toothed synchronous belt has good wear resistance, low noise and no need of lubrication, and can be used in dusty environment. It has been widely used in food, automobile, textile, pharmacy, printing, paper making and other industries.