by David Trumble
One of the most amazing inventions is the modern sewing machine.
When Elias Howe invented the sewing machine in 1846, it was an amazing mechanical device driven by human power. The evolution of the sewing machine included foot power, hand power, and eventually electrical power.
The power system of the sewing machine in those days involved the use of levers, gear, belts, and wheels. The user would start the process either by hand or foot power, and the sewing machine would transfer that movement across the sewing machine to its various parts. This enabled the machine to move the needle, hook, and feed systems to generate sewing.
Electrical motors were eventually introduced, but doing so required a new wave of invention. The mechanical devices previously used were replaced by the electrical motor. It was necessary to convert the electrical energy from the motor to mechanical energy within the sewing machine. The result was the use of a belt to transfer the power to the upper shaft of the sewing machine.
The electric motor made sewing faster, easier, and more reliable. It never got tired pumping or cranking. In the early years of this change over, existing sewing machine were often converted by replacing the hand cranks or treadles with motors mounted, aligned, and connected by belt to the machine. While the treadle and hand crank machines are now nostalgic treasures, they do not compare to the productive ability of the motorized sewing machine.
These motors convert AC (standard household Alternating Current) electricity from the home power outlet into usable kinetic energy to drive wheels, belts, gears, and levers. An AC electrical motor uses electricity to create magnetic flux between coil windings and a central core. The magnetic charges cause the center shaft of the motor to turn generating kinetic or mechanical energy. The turning shaft is connected to a gear or belt drive wheel. A belt wraps around this connection transferring the mechanical energy to the upper of the sewing machine. From this point the wheels, belts, gears, and levers transfer the energy through the sewing machine causing its parts to sew. Today many commercial sewing machines continue to use external sewing machine motors, but most home sewing machines have built in motors.
Today there are two different types of motors used in sewing machines. One is AC and the other is DC. While the flow of electricity must always operate in a continuous loop or circuit, that loop is constantly flipping back and forth with Alternating Current. That loop continues to flow in only one continuous direction positive to negative with Direct Current. Transformers are used to convert one to the other. Electric motors come in two types AC and DC. In both cases the electricity used to run the motor must operate in a continuous unbroken circuit or loop. If the flow of electricity in the circuit flows in one direction and then in the opposite direction, it is called alternating current. If the flow is in only one direction within the loop, it is DC or direct current. Use of a transformer can convert AC to DC or the reverse.
Early electric sewing machine motors were based on AC or Alternating Current electricity. These machines were essentially mechanical sewing machines using the levers and gears to move and form the stitches. Today many commercial sewing machines and low end sewing machines are still mechanical machines driven by electric AC motors. One of the hallmark features of a mechanical sewing machine is the buzz or whine the motor makes before it builds up sufficient force to move the sewing machine parts.
In recent years, another revolution has begun. The introduction of integrated computer circuits and other electronics have brought huge improvements in the reliability and smoothness of operations. Another advancement has been the introduction of DC pulse motors to control the sewing machine and produce stitches. The result has been amazing. These modern sewing machines make sewing so much easier and enjoyable.
Understanding the power system of your sewing machine will help you understand when it is functioning properly or improperly. If the machine is not working they way you expect, understanding will help you make adjustments and repairs.
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