Engineering a notched belt is usually a balancing act between flexibility, tensile cord support, and tension distribution. Precisely formed and spaced notches help to evenly distribute stress forces as the belt bends, thereby helping to prevent undercord cracking and extending belt life.
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 V Belt confusing selection of V-belts that are extremely 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, providing additional surface and greater stability. As belts operate, belt tension applies a wedging power perpendicular to their tops, pressing their sidewalls against the sides of the sheave grooves, which multiplies frictional forces that permit the drive to transmit higher loads. What sort of V-belt fits in to the groove of the sheave while working under tension impacts its performance.
V-belts are manufactured from rubber or synthetic rubber stocks, so they possess the versatility to bend around the sheaves in drive systems. Fabric materials of varied types may cover the stock material to supply a layer of protection and reinforcement.
V-belts are manufactured in a variety of industry regular cross-sections, or profiles
The classical V-belt profile goes back to industry standards created in the 1930s. Belts manufactured with this profile come in a number of sizes (A, B, C, D, E) and lengths, and are widely used to replace V-belts in old, existing applications.
They are used to replace belts on commercial machinery manufactured in other areas of the world.
All the V-belt types noted above are typically available from manufacturers in “notched” or “cogged” versions. Notches reduce bending tension, enabling the belt to wrap easier around little diameter pulleys and allowing better heat dissipation. Excessive temperature is a major contributor to premature belt failure.
Wrapped belts have an increased resistance to oils and severe temperature ranges. They can be utilized as friction clutches during set up.
Raw edge type v-belts are more 
efficient, generate less heat, allow for smaller pulley diameters, enhance power ratings, and offer longer life.
V-belts appear to be relatively benign and simple pieces of equipment. Just measure the best width and circumference, discover another belt with the same sizes, and slap it on the drive. There’s only 1 problem: that strategy is about as wrong as possible get.