5 important questions about servomotors

What is a servomotor?

A servomotor also called servomechanism and is often abbreviated to servo. The name of the servomotor comes from a Latin word servus which translated into English means slave or servant. Actually, the name servo motor is related to the term servo mechanism. It is a device used to automatically control a mechanical system without direct mechanical connections. A servo is an electric motor and it can be said that this is one of the most important motors in the 21st century in mass production.


See our offer for Panasonic servomotors

What can a servo motor do?

7 most important properties of a servomotor:

  1. Large speed range
  2. Clockwise and anticlockwise rotation and standstill.
  3. Large torque range in both directions of rotation
  4. Accurate speed and torque
  5. Short torque adjustment time
  6. High standstill torque
  7. Short lead time

These types of motors are specially developed to carry out complex and accurate assignments. They rotate 360°, can stop at specified times and have the ability to change direction, i.e. turn back and forth. They are great devices because a servo can quickly start up and then come to a standstill again. In addition, they can run at many different speeds and can be programmed very well.

How does a servo motor work?

With a servo, the motor is constantly monitored to adjust its movements. So it is more of a mechanism than a specific motor. This concerns motors that continuously keep their moment, speed, position and acceleration the same. The motors use a sensor, feedback encoder and a controller to create a feedback system.

It works step by step as follows: Servo motors run on electricity. They contain a spinning rotor on ball bearings, which is controlled by an encoder or pulse generator. Such an encoder sends a signal to a sensor, which automatically measures the position of the rotor. The sensor sends a signal to the servo amplifier, which controls the movements of the rotor. By programming the encoder, a servo-rotor has its own feedback mechanism.

What is the difference between stepper motors and servo motors?

A big misunderstanding is that a stepper motor is also a kind of servomotor, yet this is not correct and it does make a difference. With a stepper motor there is no feedback, while this is characteristic of servo motors and this is exactly what “servus” stands for.

The 4 biggest differences between a stepper motor and servo motor:

What are different types of servo motors?

More or less there are two types of servomotors. The first are DC servo motors that operate on direct current and the second are AC servo motors that operate on alternating current. Below is a table with the main features:


Engine Benefits Disadvantages
DC servo motor
  • Wash for very large powers
  • Predecessor of servo technology
  • Carbon Brushes
  • DC power supply
  • Expensive engines
  • Maintenance sensitive
AC servo motor
  • Small mass inertia
  • High speed possible
  • Fast torque build
  • High thermal load
  • Compact design
  • Low maintenance
  • Not worth mentioning
As can be seen in the table, there are no significant drawbacks for the AC servo motor. Then why would you use a reducer? Firstly, because this allows you to achieve a very low speed, possibly together with a higher torque. Second, also if you want higher torque (there are high torque servo motors only they get exponentially more expensive compared to the smaller motors). Thirdly, for inertia matching, so that the load does not determine the behavior of the motor. Fourth, to absorb the high radial or axial forces of the application. And ultimately also because gear units are available in right-angled versions and because of this you can turn a corner because otherwise the motor is outside the construction.

See our offer for Siemens servomotors


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