Engineering a notched belt is a balancing act among flexibility, tensile cord support, and tension distribution. Precisely designed and spaced notches help to evenly distribute stress forces as the belt bends, thereby helping to prevent undercord cracking and extending belt lifestyle.
Like their synchronous belt cousins, V-belts have undergone tremendous technological development since their invention by John Gates in 1917. New synthetic rubber substances, cover materials, construction strategies, tensile cord advancements, and cross-section profiles have led to an often confusing array of V-belts that are highly application specific and deliver vastly different degrees of performance.
Unlike flat belts, which rely solely on friction and will track and slide off pulleys, V-belts have sidewalls that fit into corresponding sheave grooves, offering additional surface area and greater V Belt stability. As belts operate, belt pressure applies a wedging power perpendicular to their tops, pushing their sidewalls against the sides of the sheave grooves, which multiplies frictional forces that allow the drive to transmit higher loads. What sort of V-belt fits into the groove of the sheave while working under stress impacts its performance.
V-belts are manufactured from rubber or synthetic rubber stocks, so they have the flexibility to bend around the sheaves in drive systems. Fabric materials of various kinds may cover the share material to provide a layer of safety and reinforcement.
V-belts are manufactured in various industry regular cross-sections, or profiles
The classical V-belt profile goes back to industry standards developed in the 1930s. Belts manufactured with this profile can be found in many sizes (A, B, C, D, Electronic) and lengths, and so are widely used to replace V-belts in old, existing applications.
They are accustomed to replace belts on commercial machinery 
manufactured in other areas of the world.
All of the V-belt types noted above are usually available from producers in “notched” or “cogged” versions. Notches reduce bending tension, enabling the belt to wrap more easily around little diameter pulleys and permitting better temperature dissipation. Excessive temperature is a significant contributor to premature belt failing.
Wrapped belts have an increased resistance to oils and severe temperatures. They can be used as friction clutches during set up.
Raw edge type v-belts are better, generate less heat, allow for smaller pulley diameters, enhance power ratings, and provide longer life.
V-belts appear to be relatively benign and simple pieces of equipment. Just measure the best width and circumference, find another belt with the same measurements, and slap it on the drive. There’s only 1 problem: that strategy is approximately as wrong as you can get.
