Length conversion table. A very important tool to work with belt specs is a v belt conversion table. That’s because the type of length for nominal length (the length to give when specifying a belt) is different for the different types of belts (for example, it is “inner length Li” for classic v belts – also the only error in the v belt conversion table linked above).

Li, Lw, La. For every v belt, one can give three lengths: inner length Li, effective length Lw and outer length La. These abbreviations are derived from German words “Innenlänge”, “Wirklänge” and “Außenlänge” respectively and might only be in use in Germany. Inner and outer length are the inner resp. outer circumference measure of the v belt, without any linear tension on the belt and in circular shape. Effective length is a fictive median length of a v belt that is the circumference at a certain depth of the belt profile. Namely, at a depth that has the “effective width” (German “Richtbreite”), for which see the corresponding column in the v belt conversion table. Lw is used as the nominal length of belts with profiles SP*, XP* and X*. Synonymous to Lw, some manufacturers use Ld or Lp.

Belt number. For classical v belts, there is another identification system in addition to the “20 x 3500 Li” type: the belt number (German “Riemen-Nr.”). It consists of the normal profile size designation letter and a number that normally corresponds to the inner length in inches (rounded, where necessary); for example, “Z 22” or “D 150”. A list of these numbers can be found on this v belt index.

This article comes from Mind of Matt edit released