What is a gearmotor? Technical summary for engineers

Gearmotors can be made with many different gear types. For instance, the Simogear gear motor series from Siemens features helical, parallel shaft and helical bevel gear unit types.

Updated May 2016 || By Miles Budimir • Senior Editor

Gearmotors are a fairly well-established technology. And recently, there is renewed interest in gearmotors, following a trend in integrated systems in general.

More specifically, rising energy costs are driving demand for improved process efficiencies. This presents an opening for gearmotors that can be used in a variety of applications and represents a tremendous opportunity for global energy savings.

Essentially, a gearmotor is a pairing of gear reducer and ac or dc electrical motor. The gear and the motors are combined into one unit.

A gearmotor delivers high torque at low horsepower or low speed. The speed specifications for these motors are normal speed and stall-speed torque. These motors use gears, typically assembled as a gearbox, to reduce speed, which makes more torque available. Gearmotors are most often used in applications that need a lot of force to move heavy objects.

By and large, most industrial gearmotors use ac motors, typically fixed-speed motors. However, dc motors can also be used as gearmotors … a lot of which are used in automotive applications.
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Gearmotors have a number of advantages over other types of motor/gear combinations. Perhaps most importantly, gearmotors can simplify design and implementation by eliminating the step of separately designing and integrating the motors with the gears, thus reducing engineering costs.

Precision gearheads paired with motors can meet high torque requirements. Shown here are gearmotor variations from maxon precision motors from the manufacturer’s extensive product line. Offerings include standard planetary and spur gearheads in more than 600 varieties from 6 to 81 mm and beyond; custom designs (as in the form of planetary gearheads with two speeds on the output) are possible.

Another benefit of gearmotors is that having the right combination of motor and gearing can prolong design life and allow for optimum power management and use.

Also, because gearmotors are integrated units, they eliminate the need for couplings and also eliminate any potential alignment problems. Such problems are common when a separate motor and gear reducer are connected together and result in more engineering time and cost as well as the potential for misalignment causing bearing failure and ultimately reduced useful life.

Related article: How to select a gearmotor in four simple steps

Advances in gearmotor technology include the use of new specialty materials, coatings and bearings, and also improved gear tooth designs that are optimized for noise reduction, increase in strength and improved life, all of which allows for improved performance in smaller packages. More after the jump.

A gearmotor can be simply a motor with a simple gear attached or as complex as this unit from Nord Gear incorporating bevel gears with a 90-degree hollow-shaft output. — Gearmotors can be simply a motor with a simple gear attached or as complex as this unit from Nord Gear incorporating bevel gears with a 90-degree hollow-shaft output.

Conceptually, motors and gearboxes can be mixed and matched as needed to best fit the application, but in the end, the complete gearmotor is the driving factor. There are a number of motors and gearbox types that can be combined; for example, a right angle wormgear, planetary and parallel shaft gearbox can be combined with permanent magnet dc, ac induction, or brushless dc motors.

Though there are a number of different motor and gearbox combinations available … not just any one will work for any application. Certain combinations are efficient and cost-effective than others. Knowing the application and having accurate ratings for the motor and gearbox is the foundation for successfully integrating a gearmotor into a system.