All about belt pulleys

A common form of belt pulleys is made from tubing or a rolled cylinder that forms the shell of the pulley which is made in standard diameters and lengths. Where rubber lagging is to be added to improve traction, the pulley shell may be sent to a rubber company for bonding a layer of rubber to the outer surface of the cylinder.
Other alternatives are available for the addition of pulley lagging, see for example my earlier U.S. Pat. As above noted, the solid cylindrical shell type pulley is of necessity manufactured in particular sizes, diameters and lengths, and the manufacturer is accordingly required to make a large number of different size pulleys to supply user requirements and pulley distributors are similarly required to carry a large inventory of pulleys.