A gear motor is an electrical motor that is used to turn a rotor that is connected to a shaft. They are used to create high torque at low shaft speeds or revolutions per minute (RPMs). Gear motors allow for the use of less costly motors, that produce less horsepower, while being able to create a high amount of force. Gear motors generally consist of an electric motor and a series of reduction gears. The two components are integrated to produce an easy-to-use, low-speed, high-force system.
A gear motor uses a gear train (a series of integrated gears) that is turned by a magnetic current caused by the rotation of the rotor and the shaft in the motor. The magnetic current can be created by permanent magnets or elctromagnets that only create current when the rotor is spinning. The current can be used to power gears in a reduction unit or an integrated gear box.
In most cases, the gears are then connected to a second shaft that allows the motor to create a high amount of torque while consequently slowing down the speed of the motor. This allows the motor to provide torque while drawing less current because of the reduced revolution speed of the rotor.
Gear motors come in many varieties; however, the most common types are the standard AC (alternating current) and (direct current) DC gear motors. Gear motors usually have an output range of between 1,200 and 3,600 revolutions per minute; however, there are gear motors that are designed for very specific applications that can have much lower output speeds.
Speed Reduction
The most common use of a gear motor is to reduce the speed of the rotating shaft that is connected to an integrated series of gears or a gear box. An excellent example of this would be in an old-fashioded electric clock (the type with hands). Most of these types of clocks use a small synchronous gear motor in their operation.
The current will spin the rotor at around 1,200 to 1,500 RPMs; however, the second shaft and gear system will reduce that rotation speed to only one revolution per minute for the second hand. The motor also creates enough force (or torque) to allow the second hand to overcome the friction in the gear system while maintaining very low rate of spin.
Increasing Torque
Gear motors are also commonly used to provide increased torque using inexpensive low speed (or low horsepower) motors. If you've ever seen a hospital bed being raised or lowered, then you have seen a gear motor in action. You may have noticed that the motor that raises and lowers the bed sounds like it is spinning the rotor at a very slow speed - that's because it is. However, the reduced speed also helps to create an enormous amount of force, or torque, that makes raising and lowering the bed much easier with the low horsepower motor.
High torque, low-speed gear motors can also be found in many other common types of equipment around your home. For instance, can openers, garage door openers and the timer cycles on your washing or dryer machine usually use gear motors as well.
