Engineering a notched belt is a balancing act between flexibility, tensile cord support, and stress 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 life.
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 methods, tensile cord advancements, and cross-section profiles have led to an often confusing selection of V-belts that are highly application particular and deliver vastly different degrees of performance.
Unlike toned belts, which rely solely on friction and will track and slip off pulleys, V-belts have sidewalls that match corresponding sheave grooves, offering additional surface and greater stability. As belts operate, belt stress applies a wedging push perpendicular with their tops, pushing 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 into the groove of the sheave while working under pressure 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 varied kinds may cover the stock material to provide a layer of security and reinforcement.
V-belts are manufactured in various industry standard cross-sections, or profiles
The classical V-belt profile dates back to industry standards developed in the 1930s. Belts manufactured with this profile come in many sizes (A, B, C, D, E) and lengths, and so are widely used to displace V-belts in old, existing applications.
They are used to replace belts on commercial machinery manufactured in other areas of the world.
All of the V-belt types noted over are usually available from producers in “notched” or “cogged” versions. Notches reduce bending stress, enabling the belt to wrap easier around little diameter pulleys and allowing better warmth dissipation. Excessive heat is a major contributor to premature belt failure.
Wrapped belts have an increased resistance to oils and intense temperature ranges. They can be used as friction clutches during start up.
Raw edge type v-belts are better, generate less heat, enable smaller pulley diameters, enhance power ratings, and offer longer life.
V-belts appear to be relatively benign and basic devices. Just measure the top width and V Belt circumference, discover another belt with the 
same dimensions, and slap it on the drive. There’s only one problem: that approach is approximately as wrong as possible get.