Introduction: For the determination of resistance of aggregate to wear by abrasion. Two hollow cylinders, closed at one end and provided with tightly fitting covers at the other end. The inside diameter of the cylinder 20 cms and 34 cms depth. The cylinders are mounted on a shaft at an angle of 30째 with the axis of rotation. The shaft rotates at 30-33 rpm through a reduction gear, coupled to a motor. Suitable for operation on 440 volts, three phase, 50 cycles, AC supply. Supplied complete with a counter and push button starter. With 12 nos cast iron spheres or steel spheres (steel balls) hardened, approx. 48 mm in diameter, each weighing 380-445 gm.