This document discusses different types of pulleys used for flat belts, including their materials and designs. It describes cast iron, steel, wooden, and paper pulleys. Cast iron pulleys are commonly made with a rounded rim and may be solid or split. Steel pulleys are lighter than cast iron and made of pressed steel in two halves. Wooden pulleys are lighter than other materials but absorb moisture. Paper pulleys are used when shaft spacing is small. Fast and loose pulleys allow machines to be started or stopped independently. The document also provides procedures for designing cast iron pulleys, including determining dimensions based on diameter, belt width, torque requirements, and number and shape of arms.