The pulleys are generally made of cast iron, because of their low cost. The rim is held in place by web from the central boss or by arms or spokes. The arms may be straight or curved as shown in Fig. 1 (a) and (b) and the cross-section is usually elliptical.
Compared to other materials, such as plastics or nylon, only aluminum has the sufficient capacity for such horsepower drive systems. Great tensile strength. Its tensile strength capacity makes it an ideal choice if you wish to put heavy materials as its load capacity is high.