Sewing Machine Motors | Motor Sewing Machine

Two types of motors power sewing machines. One is an AC (alternating current) motor, the other is a DC (direct current) motor.
AC Motors
The AC motor uses power as it comes from your wall outlet. The voltage will depend on the part of the world you live in. These motors last a very long time. When you take an older machine with this type of motor to the shop for maintenance, the sewing machine technician should check the motor brushes for wear.
The downside of these motors is that they do not have very much power at low speed. That means the sewing machine can labor when you need to sew slowly. This can be a problem when sewing over dense fabric or many layers. They can be so weak that when you start to sew, you might have to help by turning the handwheel by hand. Manufacturers have overcome some of this problem with circuitry, but many lower-end sewing machines suffer from this lack of power. 

DC Motors
DC (direct current) motors do not use the power as it comes from your wall outlet it needs to be converted from AC to DC and regulated to the appropriate voltage for the motor used. This requires what is commonly referred to as a power circuit board. Most mid -to top-end sewing machines have DC motors. Their advantages can make them desirable.
If you are the type of sewist who likes control and precision, then a machine that features a DC motor is for you. DC motors offer much more piercing and feeding power at slow speeds. This makes climbing over that seam in a pair of jeans much less daunting. Some brands use sensors that can detect the amount of resistance the needle is meeting and instantly provide more power to help push through.
DC motors are easier to use at slow speeds.
A light touch on the foot control, and the machine will start. No need to help the handwheel. Some manufacturers have devised ways to meter power to these motors that allow them to stop the instant you take your foot off the controller. This is a feature that gives you far more precision and control over your sewing. Some machines allow half-stitch by half-stitch forward and reverse movements. This puts you firmly in the driver’s seat!

With all that available power, manufacturers needed to create fail-safes to protect the machine and motor if a needle hits something solid. This has been accomplished in two ways. Some machines use fuses that burn out when the motor can no longer turn.
This does offer the required protection, but the fuses are not easily accessible for replacement. This means a trip to the shop. A more sophisticated method uses sensors that shut down the motor when too much resistance is met. Once the cause of this resistance is removed, the machine goes about its business again.