DEVICE FOR PROTECTING OVERLOADING OF GEAR GRINDING DEVICE

PURPOSE:To release engagement when an engaging load becomes excessive by separating a wheel spindle from a work spindle when the detected value of a first position detecting means or a second position detecting means is different from a determined rotating position value. CONSTITUTION:A grinding wheel 3 and a workpiece gear 7 are synchronously rotated by the drive of a wheel driving motor 9 and a work driving motor 10, and a vertical moving motor 20 as a wheel feed motor is driven to make the grinding wheel 3 cut in to carry out grinding. The rotating positions of the wheel spindle 9a of the wheel driving motor 9 and the work spindle 10a of a work driving motor 10 are detected by a wheel spindle pulse generator 21 as a first position detecting means and a work spindle pulse generator 22 as a second position detecting means and, when the positions are different from predetermined positions, i.e., when the rotating phase of the grinding wheel 3 or the workpiece gear 7 is different from a determined condition, the wheel feed motor 9 is driven by a control device 38 to release the grinding wheel 3 from the workpiece gear 7.