the flexible element of a belt drive. Since belts largely determine the operating capacity and durability of belt drives, they should have high traction and fatigue strength, sufficient flexibility, and as high a coefficient of friction as possible. Depending on the shape of their cross sections, belts are classified as flat belts, V-belts, multiple V-belts, and round belts.
Flat belts may be leather, rubberized, or fabric (cotton or wool). Leather belts are made from strips of high-quality hide that are glued or sewn together. Rubberized belts consist of several layers of a strong fabric, such as belting, held together by vulcanized rubber; these are the belts most often used in belt drives. Fabric belts are made of several layers of strong cotton or wool yarn. V-belts use several layers of cord fabric or strings in a rubber filler. The outer surface of the belts is wrapped with several layers of rubberized fabric. Cog belts are V-belts that have transverse teeth on the underside to increase flexibility. Multiple V-belts have a flat outer surface and lengthwise V-shaped protrusions on the underside; they are reinforced with braided cord.
Round belts are made either of cotton or leather and usually have a small diameter (4–8 mm). The use of polymer belts made from polyamide resins is promising; the belts can transmit high powers (hundreds of kilowatts) at high speeds (up to 100 m/sec).
A. A. PARKHOMENKO