{TAIL ~ The servomotor} 27 moves {HEAD ~ the grinding wheel head} 8 such that the grinding wheel 14 advances and retreats according to the profile data PFD while undergoing a rough grinding feed shown in FIG 9; i.e., while being fed for cutting against the crank pin P. Thus, the grinding wheel 14 advances and retreats according to the revolving motion of the crank pin P while being gradually fed for cutting 
{ TAIL ~ The servomotor } 27 moves { HEAD ~ the grinding wheel head } 8 such that the grinding wheel 14 advances and retreats according to the profile data PFD while undergoing a rough grinding feed shown in FIG 9 ; i.e. , while being fed for cutting against the crank pin P. Thus , the grinding wheel 14 advances and retreats according to the revolving motion of the crank pin P while being gradually fed for cutting
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