Hydraulic Expanding OD Grinding Mandrel. CONCENTRIC Hydraulic Chuck V/s Collet Chuck - Run-out of collet chuck is easlly changed according to what and how to Combinate, but hydraulic chuck always keep the same run-out accuracy. - Clamping force up to four times. - Damping properties of hydraulic chuck extend tool life. - No required torque wrench. - Provide a coolant function without special parts or accessories. - Easy clamping / unclamping by T-wrench.