Conventional (wide/classical) sheaves are manufactured from class 30 gray iron (30,000 tensile strength) and can have a maximum speed of 6500 fpm. All Martin sheaves are statically balanced. Dynamic balancing should be considered for any sheaves exceeding 5000 fpm, or if they will be used on equipment where vibration is a problem. Martin has extensive inventories of both QD and TB style V-belt sheaves to accept "A", "B", "C", and "D" belts. Martin Single Groove Conventional Sheave, Arm/Spoke Type C-3, QD® Bushed Bore, 1/2 to 2 in Bore Dia, 12-3/4 in Outside Dia, 12.4 in, 1 in Face Width, SDS Bushing, 1.63 in Overall Length, For Use With: A/B Cross Section Belts, Cast Iron