Newlong Industrial Japan 281131A Variable Diameter Pulley Assembly for Ds-9a, Ds-9c, DS-9cw

A variable pulley, also known as a variable speed pulley or adjustable pulley, is a mechanical device used to change the rotational speed of a shaft in a belt-driven system. It achieves this by altering its effective diameter, which in turn changes the speed ratio between the driving and driven shafts.  

The fundamental principle behind a variable pulley 281131A from Newlong Industrial  lies in the relationship between the diameter of the pulleys and their rotational speeds. For a given belt speed, a larger pulley diameter will result in a lower rotational speed, and a smaller diameter will result in a higher rotational speed. Variable pulleys exploit this principle by allowing their working diameter to change.