A V-belt drive transfers power between two parallel shafts. Each shaft has a V-belt pulley attached, and the belt then connects the pulleys. The tension cords integrated into the V-belt is one of the factors that determines belt strength. The production material depends on the type of belt. Most of the belts are made of polychloroprene (PCP) or polyurethane (PU), the tension cords are mostly made of polyester (PES) and in one case from aramid. Aramid has an extremely low elongation propensity, meaning very high performance transmission can be achieved.
A V-belt needn’t always provide power transmission, it can also be used for transporting products. In most cases, this type of belt is made of PU and can be found in the product group “weldable belts”.
V-belts are available in numerous variants and dimensions. The best-known are the encased V-belts and the toothed narrow V-belt, also called a raw-edged, moulded notched V-belt. These belts are available with the following profiles: Z, A, B, C and D, SPZ, SPA, SPB and SPC, as well as XPZ, XPA, XPB and XPC.
There are also a great number of other variants, such as polyflex belts (with an edge angle of 60°), ribbed micro-V belts, segmented belts and multi-speed variator belts.
Most of the V-belts are also available in a variant known as Powerband.
Several factors determine which V-belt type is best suited to a particular drive, for example the application (what is being driven?), the power to be transferred, the desired speed (acceleration or deceleration) as well as the centre distance of the pulleys and any possible impact loads.
It is also important to know what ambient conditions are present and whether there are any space limitations (what is the maximum width and diameter of the pulleys?).
V-belt drives can slip to a certain extent, but this need not necessarily be a problem. It is sometimes even desirable for safety reasons. If absolutely no slip is permissible, toothed belts or chain drives are among the options.
It is very important that the belt is pre-tensioned correctly for optimal drive function. Tension can be measured with a testing device such as the Sonic Tension Meter. This uses sound waves transmitted by the belt to determine its vibration frequency and then calculates a tension value from this. As well as correct tensioning, it is important that the pulleys are aligned correctly: this is achieved with a laser-guided alignment system. V-belts must generally be re-tensioned after certain run-in period or operating time, but some V-belts are completely maintenance-free, such as the Quad-Power® 4. After setting the initial pre-tension, no further re-tensioning is necessary on this belt.
Common standards for V-belt drives include: DIN2211, DIN2217, DIN7867, ISO4183, ISO5290 and ISO9981. Finally it is important whether the V-belts need to be static-conductive to meet ISO1813 (ATEX environments).
