Devices for preselecting speed of working-spindle

Full Title

Driving or feeding mechanisms; Control arrangements therefor (automatic control B23Q15/00; copying B23Q33/00, B23Q35/00; specially adapted for boring or drilling machines B23B39/10, B23B47/00 ) > Driving main working members > rotary shafts, e.g. working-spindles > Mechanical drives with means for varying the speed ratio > Devices for preselecting speed of working-spindle