How does a sewing machine work?

Question

How does a sewing machine work on the inside? Are there gears or something?

Answer 1

The needle bar goes down, carrying the upper thread with it.  As the needle bar goes up, a loop of the upper thread (caused by friction between the thread and the fabric)  is formed and picked up by the hook, which rotates behind the needle.  This thread is carried around the hook which contains the lower thread encased in a bobbin case.  As the thread passes around the hook it entwines with the lower thread, forming a lock-stitch.  After the needle has continued in its' upward motion to a point at which it is above the fabric, the feed-dogs rise and begin their motion backwards.  This motion, in conjunction with the pressure of the presser foot, carries the fabric a small distance.  This distance is regulated by the stitch length lever.  After the feed has traveled the appropriate distance it drops under the needle plate and returns to its' starting position and the whole thing starts over again.  Pretty simple.

Answer 2

Yes, there are gears that power the needle up and down, the feed dogs to feed the fabric through, and the bobbin to form the lock stitch.  There's also a lever that pulls the thread tight.  The gears keep everything synchronized.

Answer 3

there are gears, there is also a motor inside to run it all, there are, hook and needle syncs, there is a pressure bar, feed dogs, pendulum swing, a crank shaft. tension discs for the thread to go in, always thread machine will presser foot up, and two hands on thread until it is time to thread needle. hopefully this will help for now.  happy sewing!