Hi-Cap® sheaves (narrow V-belts) are manufactured from class 30 gray iron (30000 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 run with 3V, 5V and 8V belts. Martin Hi-Cap® Wedge Stock Sheave, Arm/Spoke Type A-3, QD® Bushed Bore, 2 to 4-3/4 in Bore, 21.2 in OD, 21 in Pitch Diameter, 8 Grooves, 9-3/8 in Face Width, M Bushing, 9.38 in Overall Length, For Use With: 8V Cross Section V-Belts, Gray Cast Iron