V-Ribbed Belts

Nov. 15, 2002
The V-ribbed concept combines some of the best features of flat belts and V-belts.

The V-ribbed concept combines some of the best features of flat belts and V-belts. It employs what is essentially a flat belt with a series of V-shaped ribs running the length of the belt on the driving surface. These thin belts operate efficiently and can run at high speed. But even more important, tensile cords have total support because the belt ribs bottom completely on the sheave; there is no wedging action. The total support of the cord permits high load-carrying capacity. Theoretically, this design could provide the highest capacity of any belt if reinforced with high-strength fiber. To date, however, there has been no commercial demand for such exceptional power capacity in this type of belt.

The sacrifice of wedging action in V-ribbed belts increases tensioning requirements, but not to the levels required by flat belts. Supposedly, friction is independent of area of contact. Nevertheless, the V-ribbed shape increases friction between belt and sheave considerably beyond that of flat belts. Consequently, tensioning requirements are only about 20% above those of V-belts. In addition, the ribs ensure that belts track properly, making alignment less critical than it is for flat belts. Flat-belt alignment requirements are more critical than those of V-belts.

Major applications of the V-ribbed belts are in mass-produced consumer goods such as snow blowers, home power tools, and clothes dryers. It is also on accessory drives in automobiles. Operating efficiency of the V-ribbed belts rivals that of flat belts and synchronous belts. It also is able to operate over small pulleys. Because it is available in small width increments of one-rib width, belts can be matched almost precisely to the power requirements of specific drives. V-ribbed belts are not recommended for clutching drives.

The belt performs well with reverse-bend idlers, and most applications involve high-speed ratios with a reverse-bend idler used for take-up and to increase the arc of wrap on the smaller pulley.

Five standard configurations are available, with designations of H, J, K, L, and M. L and M were the first to be introduced and are intended primarily for industrial and agricultural drives. The M section is capable of transmitting up to 1,000 hp. J (originally called JR) is normally applied to fractional-horsepower drives in home appliances, snow blowers, and power tools. H is intended for miniature drives and K for automotive accessory drives.

The V-ribbed section, because it is available in extremely high-power ratings, eliminates matched-set belts required in multiple V-belt drives. The power density also permits compact drive configurations.

The most effective use of V-ribbed belts normally requires testing the drive system. Some tooling investment may be necessary for pulleys. The user also may find it prudent to draw upon the belt manufacturer for technical help and design refinement. Therefore, the V-ribbed concept is almost always applied to mass-produced drives.

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!