AC Gear Motor Selection Methods for Design Engineers

Sinotech    April 1, 2013

120 Watt 90mm AC Gearmotors

120 Watt 90mm AC Gearmotors

Choosing the right AC gear motor for your gearbox and application can be tough because of all the factors you must consider. As you begin your search, use the following guide to help you determine the features that are right for you.

Basic Parameters

When choosing an AC gear motor, it’s important to know the basic specifications you need. Before you begin your search, know your specification requirements for the following parameters:

  • Horsepower
  • Speed
  • Efficiency
  • Maintenance
  • Product life
  • Starting torque
  • Noise
  • Speed regulation
  • Other product-specific requirements

Package Size

As you design an AC gear motor, use the motor size and speed requirements to come up with the optimal output power. By comparing the general performance and desired torque with the application requirements, you can determine the best frame size for your gear motor.

Gearbox Options

There are four basic configurations an AC gear motor can have: planetary, parallel shaft, right angle bevel and right angle worm. There are also gearing components to consider: worm, spur, bevel and helical. The right combination helps ensure the gearbox’s overall performance.

Reducer Matrix

Just as you must consider the basic parameters you need, you’ll need to determine the key reducer parameters, such as:

  • Noise
  • Duty cycle
  • Maximum input speed
  • Efficiency
  • Noise
  • Back drivability
  • Maximum torque

It’s important to keep in mind that the efficiency of an AC gear motor depends on the quality of the gears, ratio, lubrication, gear type, bearing type and side loading.

As you decide on the gearbox attributes you seek, don’t forget to weigh the limitations of each. The most common limitations are thermal (heat) and mechanical (wear).


In addition to the cost, torque and speed of an AC gearbox, it’s helpful to pick an AC gear motor based on your primary constraints. As you design the gearbox, make sure you know the desired:

  • General requirements – Envelope size, lubrication selection, side loads, overhung loads and mounting type and orientation
  • Input power source – Voltage, maximum current, frequency and control type
  • Gear motor specifications – Noise, maintenance, life expectancy, size and weight
  • Gear motor performance – Starting/stall torque, speed, torque and duty cycle
  • Environment – Ambient temperature, application temperature and ingress protection rating

With so many things to think about when choosing an AC gear motor, one of the best ways to go about the task is with the help of a motor consultant. After going through our gear motor catalog, note the items of interest and talk with a consultant about how Sinotech can create a product based on your needs.

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