▁in ▁un ison , ▁inter connected ▁in ▁series ▁by ▁six ▁or ▁more ▁links — a ▁Schmidt ▁coupling ▁can ▁adapt ▁to ▁wide ▁variations ▁in ▁radial ▁disp lacement ▁while ▁running ▁under ▁load . ▁ ▁History ▁▁ ▁In ▁ 1 9 6 0 , ▁NASA ▁commission ed ▁Richard ▁Schmidt ▁of ▁Mad ison , ▁Alabama , ▁to ▁develop ▁a ▁prop ulsion ▁system ▁for ▁rock ets ▁in ▁zero - gravity ▁environments . ▁One ▁of ▁the ▁solutions ▁suggested ▁was ▁a ▁system ▁of ▁rot ating ▁disc s ▁with ▁mass ▁points ▁position ed ▁along ▁their ▁circum ferences . ▁To ▁power ▁these ▁disc s , ▁Schmidt ▁used ▁rot ating ▁slider ▁c ran ks ▁similar ▁to ▁those ▁used ▁to ▁transfer ▁power ▁to ▁the ▁whe els ▁of ▁a ▁steam ▁locomot ive . ▁ ▁Similar ▁disc - and - link ▁arrangement ▁had ▁been ▁known ▁to ▁German ▁engine ers ▁for ▁some ▁time , ▁but ▁engine ers ▁could ▁not ▁make ▁the ▁theory ▁work ▁in ▁practice ▁because ▁they ▁err one ously ▁assumed ▁the ▁center ▁disc ▁would ▁require ▁its ▁own ▁bearing . ▁Schmidt ▁found ▁that ▁the ▁center ▁disc ▁could ▁in ▁fact ▁assume ▁its ▁own ▁center ▁of ▁rotation . ▁ ▁Schmidt ▁further ▁ref ined ▁the ▁design , ▁creating ▁a ▁coupling ▁system ▁that ▁guarante es ▁a ▁completely ▁true ▁angle ▁of ▁rotation ▁at ▁all ▁times . ▁Additionally , ▁Schmidt ’ s ▁design ▁elimin ates ▁the ▁generation ▁of ▁net ▁external ▁forces , ▁as ▁its ▁pushing ▁and ▁pulling ▁forces ▁alternate ▁and ▁overlap ▁in ▁a ▁sin us oid al ▁pattern . ▁ ▁In ▁May ▁ 1 9 6 3 , ▁Schmidt ▁applied ▁for ▁a ▁pat