Engineering a notched belt is definitely a balancing act among versatility, tensile cord support, and tension distribution. Precisely formed and spaced notches help evenly distribute tension 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 compounds, cover materials, construction strategies, tensile cord advancements, and cross-section profiles have led to an often confusing selection of V-belts that are highly application specific and deliver vastly different degrees of performance.
Unlike toned belts, which rely solely on friction and can track and slide off pulleys, V-belts possess sidewalls that fit into corresponding sheave grooves, providing additional surface and greater stability. As belts operate, belt stress applies a wedging push 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. How a V-belt fits in to the groove of the sheave while working under stress impacts its performance.
V-belts are produced from rubber or synthetic rubber stocks, so they have the versatility to bend around the sheaves in drive systems. Fabric materials of various types may cover the stock 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 dates back to industry standards developed in the 1930s. Belts produced with this profile can be found in several sizes (A, B, C, D, Electronic) and lengths, and are widely used to replace V-belts in old, existing applications.
They are accustomed to replace belts on industrial machinery manufactured in other parts of the world.
All of the V-belt types noted above are usually available from producers in “notched” or “cogged” variations. Notches reduce bending stress, allowing the belt to wrap more easily around small diameter pulleys and permitting better 
high temperature dissipation. Excessive high temperature is a major contributor to premature belt failing.
Wrapped belts have an increased resistance to oils and intense temperature ranges. They can be used as friction clutches during set up.
Raw edge type v-belts are more efficient, v belt china generate less heat, enable smaller pulley diameters, increase power ratings, and offer longer life.
V-belts look like 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 one problem: that strategy is approximately as wrong as possible get.