The document discusses the process for selecting an electric motor for use in a gearbox. It notes that selection involves considering key parameters like voltage, torque requirements, environmental conditions, and size. The selection process begins by gathering technical and financial requirements for the application. These are used along with manufacturer specifications to choose a motor that meets the needs. Important factors include required speed and torque, efficiency, lifetime, and noise levels. The process may involve a gearbox to reduce motor speed to the necessary output level. Matching motor and gearbox performance curves is key to a successful integration that optimizes the application.

1. Motor Selection for Gearbox

2. Lecture Outline
• Overview
• Selection Process
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3. Overview
• Selection of an electric motor for an application
can be one of the demanding tasks that the
design engineers face.
• There are so many types of electric motors to
choose from and promising to be the “most
efficient”, of the “highest quality” or having the
“highest precision”.
• There are several key design parameters that
should be considered when selecting an electric
motor for a motion control application.
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4. Selection Process
• As the motor selection process begins, the
designer must gather the relevant technical and
financial requirements.
• The gathered design inputs will then be used in
the selection process and will ensure that the
ideal motor is taken for the application.
• It is helpful to use an Application Checklist (Table
1) when developing the motor specifications.
• These parameters, along with the project
specific requirements, will be helpful when
navigating through the selection process. 4

5. Table 1: Application Checklist
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Input Power Source
• Voltage (V)
• Frequency (Hz)
• Maximum Current (A)
• Control type (if applicable)
Working Environment
• Ambient Temperature
• Application Temperature
Motor Specifications
• Size and Weight
• Life Expectancy / Maintenance
• Noise Level
Motor Performance
• Speed and Torque
• Starting Torque
• Service Cycle (“On time and “Off” time)
General Requirements
Mounting orientation and type, Overhung
and side loads, Space availability,
Lubrication selection

6. Selection Process contd..
• Next, the designer must consider what type of
motor technology best suits the intended
application.
• Design inputs and the manufacturers’
catalogues can be used as a means of guidance
during the decision process.
• Since each application has its own unique
characteristics, it is important to determine which
of the parameters (e.g. Motor power, efficiency,
life time, starting torque or noise ratings) are
most important related to the application under
consideration. 6

7. Selection Process contd..
• During the motor selection process, by looking at
the required speed and torque of the application,
it should become evident to the designer if the
motor chosen requires a speed reduction
mechanism (belt/chain drive etc.) to meet the
necessary output speed requirements.
• This will add another level of complexity to the
application and several additional criteria need
to be evaluated.
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8. Selection Process contd..
• Conceptually, motors and gearboxes can be
mixed and matched as needed to best fit the
application.
• Though there are a vast number of different
motor and gearbox combinations available, not
just any one will work for the application.
• There will be certain combinations that will be
more efficient and cost-effective than others.
• Knowing the application and having accurate
ratings for the motor and gearbox is the
foundation for successfully integrating the
systems. 8

9. Selection Process contd..
• Speed and torque required for the application is
critical in selecting the motor-gearbox
combination.
• By using the speed and torque requirements,
designer can select the manufacturer’s
performance curves that match the application
needs.
• Finally, after selecting the motor that appears to
meet the application needs, it is important to
review the limitations.
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10. Selection Process contd..
• The following information should also be
looked at, to determine if the chosen
electric motor will cause any issues within
the application.
 Full-load gearbox torque
 Gearbox input speed
 Strength of gearbox components
 Intermittent service considerations
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11. Selection Process contd..
• It is important to take time and apply maximum
effort to properly select an electric motor, since a
hasty decision and lack of testing can cause a
host of problems with the motor-gearbox
combination and could possibly damage the
application.
• Though the motor selection process can be
demanding, a properly matched motor-gearbox
system can last for years and will optimize the
application to its peak potential & efficiency and
reduce operating costs as well. 11