DC Motor Basics

April 23, 2018

Watch our short video on DC Motors.

DC motors are the most common type of motor for low voltage and/or high starting torque applications, most often seen in the automotive and agricultural industries.

DC motor components

DC Motor Construction and Operation

A DC motor is comprised of a wound armature, commutator, brushes and magnetsall within a totally-enclosed housing.

Rotation occurs when the magnetic field of the motorcreated by the permanent magnets in the housinginteracts with the commutator through graphite or carbon brushes.

DC Motor Characteristics

  • Runs on DC power or AC line voltage with a rectifier
  • Operating speeds of 1,000 to 5,000 rpm
  • 60-75% efficiency rate
  • High starting torque
  • Low no-load speeds

DC Motor Advantages & Disadvantages

Advantages Disadvantages

Operates on DC power supply without a control

High maintenance due to low brush life (2,000 hrs max in continuous duty applications)

Inexpensive controls for speed regulation

Cogging at speeds of less than 300 rpm

Generally a low-cost motor option

Significant power loss on full wave rectified voltage

Easily pairs with gear reducers

High starting torque can damage reducers


DC Motor Performance Curves

DC Motor Performance Curve

Here we have the typical speed-torque curve of the DC motor.

Looking closely, we can see an interesting phenomenon with the hot motor curve. As the motor temperature rises, the no-load speed also increases. This is due to the effect heat has on the magnets. As the motor cools down, the speed will return to normal. The same concept applies to the other end of the curve where stall torque is reduced for a “hot” motor. Notice the efficiency curve and how under ideal circumstances the motor’s peak efficiency will occur near the motor’s operating torque.

AC, Brushless DC, and DC Motors can be used with a control to adjust motor speed. Generally, fractional horsepower DC motors don’t need to rely on controls for optimal performance, unlike AC and BLDC motors. DC controls operate by varying the voltage sent to the motor.

DC Motor Wrap Up

To pull everything together, DC motors are great when needing a fairly inexpensive motor option with high starting torque capabilities. Their versatility with power supply gives them the ability to run in portable or remote locations.

How to use the Motor Search Tool

Narrow your search by selecting motor type, gearbox, voltage, and phase options for your desired motor.

Select a dominant variable: choose one of the three parameters to narrow your search. The selected variable determines which slider bar you will be able to manually move.

Use the slider corresponding to your dominant variable to further narrow your motor selection. The other sliders will automatically move to show available ranges based on the range of your selected variable.

Results will upload as your search criteria changes. If you have any questions regarding your results or how to use the search tool, you can chat with us using the green tab on the left-hand side of your screen.

Note: Groschopp Universal motors are custom built to fit your application so no additional options are available to narrow the search. Selecting the Universal motor type will prompt a message taking you to the Universal product page.

Not sure what you need?

One of our team members would be happy to help. Contact us at 800-829-4135 or by email at sales@groschopp.com. You can also chat with us using the green tab on the left side of your screen.

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Universal Motors

Groschopp Universal motors are custom built to fit your application so no additional options are available to narrow the search. Standard frame sizes and motor features can be found on the Universal page.

go to Universal page