1. 1  Axial hydraulic grinder This powerful hydraulic grinder is ideally for hard grinding work and for underwater work with grinding pins and milling cutters. - 6 mm Collet - 11.500 rpm free speed - 0,8 kW Power - 10-30 l/min oil flow - 90,7 dB(A) noise level - <2,5 m/S2 vibration level - 1/2.