Dayton automatic motor bases are designed to automatically adjust the tension in a motor's belt while in use. They are suitable for fan, blower, pump and compressor applications. These motor bases feature 2 adjusting bolts that reduce stress and increase the life of belts and bearings. They provide linear adjustments and have NEMA 56 frame construction to accommodate the motors. Choose from a wide range of adjustable motor bases, available in 9.5, 11-11/16, 14-1/6, 16.375, 19.5, 22.125, 29.25, 32, 34.5 and 37.5 inch lengths on Raptor Supplies.