The Difference is in the Name

Use of AC or DC Motors in Speed Reducers

A type of mechanical speed reduction equipment utilized in automation control systems is the gearbox, also referred to as a speed reducer. At Romanoff Industries, we are your source for various types of electric motors and other electrical equipment designed to fulfill the requirements of various industry applications.

Purpose of Speed Reducers

There are two purposes for which speed reducers are utilized. The chief use is to multiply the torque generated through an input power source in order to increase the quantity of usable work. These speed reducers also lower the input power source speed in order to obtain desired output speeds.

Gearboxes (or speed reducers) are used to increase the amount of torque while reducing the prime mover output shaft speed – for example, a motor crankshaft. A gearbox has an output shaft output that rotates slower than the rotation of the input shaft. The reduction in speed of the output shaft generates a mechanical advantage that increases torque. Gearboxes can also be configured to work in the opposite manner, increasing the rate of rotation of the output shaft and reducing torque.

Gear drives and gearboxes are designed with two major configurations – right angle and in-line which use different types of gearing. Right angle speed reducer designs are usually manufactured with bevel or warm gearing, although hybrid drives are sometimes used. In-line speed reducers are often manufactured with planetary gears, spur or helical gears, harmonic wave generators, or cycloidal mechanisms. The type of speed reducer design that satisfies requirements best is dictated by the type of application involved.

Commonly Used With DC Motors

A DC motor has an average shaft speed of between 1500 to 6000 RPM under load. With many applications, these types of shaft speeds are beyond the acceptable range by considerable amount. In order to reduce these speeds, DC motors are often featured with a gearbox. The gearbox reduces the speed of the motor shaft and increases the motor’s torque output. Most of the time, the torque is increased according to the ratio of the gear reduction, subtracting any losses from the gearbox.

For more information about the range of electric motors, gear reducers, and transformers we offer at Romanoff Industries, call our team today at 800.366.8778 or email us at