Question: what are the three major parts of a lockstitch sewing machine?
Answer: Spool pin: The main function of spool pin is to hold the spool of thread. Bobbin binder spindle: During winding, bobbin is placed here. Bobbin winder stopper: ...  Stitch width dial: ...  Pattern selector dial: ...  Hand wheel: ...  Stitch length dial: ...  Reverse stitch lever: