Gearmotors & Gearboxes

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Marshall Wolf Automation is your authorized distributor for a number of gearmotor and gearbox manufacturers. Our inside sales and in-house tech support can help with replacements, cross referencing another manufacturer or helping you find the best geamotor for your application. Our lines include Lenze, SPG, Motovario, Bonfiglioli and Transtecno.

What is a Gearmotor?

A gearmotor is an electrical motor that has some type of gear system on the output of the motor, the gear system is called a gear reducer or gearbox.

Gearmotors are commonly found when an application needs a lot of force to move heavy objects. They are generally used to reduce speed in a series of gears which creates more torque. Gear motors are designed to produce high torque while maintaining low horsepower, or low speed, motor output.

You might be surprised to find that gearmotors are used in everything from washing machines and garage door openers to hospital beds and cranes.

Gearmotors are available with either an AC or DC motor. AC (alternating current) is the most common, DC (direct current) is generally used in automotive applications for things like adjusting automatic seats and side view mirrors.



Gearmotors can have many types of gearboxes:
  • Spur gears - simple, straight teeth mounted on a parallel shaft
    • Low cost and compact
    • Noisy and teeth are prone to wear
  • Helical gears - angle toothed gear
    • High power
    • Compact with balanced gear load distribution
    • Maintenance can be difficult
  • Worm gears (also called worm reducers) - uses right angled drives where a worm drives a wheel coupled to the output shaft. Great for high reduction and compact right-angle power transmission.
    • Right angle
    • Highly precise and maintenance free
    • Low noise
  • Bevel gears - intersecting axes that are usually perpendicular
    • Right angle
    • Durable

Output Shaft

In-line output shaft has axis in-line with the axis of the motor rotation. Great for high reduction ratios and high-torque applications.

Parallel output shaft (offset) has its axis parallel to the axis of motor rotation. Ideal when space is limited.

Right angle output shaft has the axis perpendicular to the motor rotating axis (intersecting or not). Great for short reduction ratios.


A common issue is under or oversizing a gearmotor; there is more to consider than just speed and torque.

Speed, RPM, is the rotational speed of the shaft generated by the motor. Rpm stands for rotations per minute. The shaft speed is proportional to the gear ratio; divide the input speed by the gear ratio. If it's above one it will reduce speed, gear ratios below one will increase speed.

Torque is the angular force generated by the motor to handle a required load. You will find this expressed as ft-lb or N-m (newton meters).

Gear ratio, also called gearbox ratio is directly proportional to the correlation between the number of teeth of different gears in the system. For example, if an output gear has 20 teeth and an input gear has 10 teeth your gear ratio is 2:1.

Gearbox efficiency is the percentage of power that is transferred through a gearbox.

Backlash is the gap between the teeth of two adjacent gears, basically the angel that the output shaft of a gearbox can rotate without the input shaft moving.

Cross References

We are able to cross reference most manufacturers of gearmotors including:
  • Nord
  • Baldor
  • Oriental Motor
  • Brother
  • Bodine
  • Bison
  • Sumitomo
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