×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# sizing a motor2

 Forum Search FAQs Links MVPs

## sizing a motor

(OP)
Hi All,
I have to size a motor for a rotary device (a drum). The drum has a normal force applied to it. What would be the best way to size a motor for such a system?

Thank you.
Replies continue below

### RE: sizing a motor

Evaluate all of the various torque needs -

acceleration torque - what is the mass moment of inertia of the system and how fast does the system need to get up to steady-state speed?

operating torque - how far off of normal is the force application, will this create a torque need? How is the force applied to the drum - with a roller? What sort of interface forces are created tangentially? Deformation torque - will the applied force deform the drum? Bearing frictional torque, including seals. Misalignment torque.

### RE: sizing a motor

Second what dvd mentioned. Look at the torque required to operate the device in a steady-state (or at least minimally transient) condition. Then look at the acceleration time/torque requirement. Then look at whether the application requires constant or variable speed - and how does the required load torque change with that speed?

Constant torque applications will (usually) require a somewhat higher nameplate power rating compared to variable torque designs to provide sufficient mass to handle the thermal issues inherent to the operation.

Converting energy to motion for more than half a century

### RE: sizing a motor

(OP)
Hi,
I tried finding the torque for the motor, just want to make sure if this makes sense.

The wheel is being pushed to the drum with a force, the drum is 3-4 times bigger in diameter compared to the wheel.

I did T= F*perpendicular distance.

I am using the radius of the drum, because the wheel is pushing on the drum, does this make sense.

### RE: sizing a motor

In another post you linked to this video: https://www.youtube.com/watch?v=Iuya2buTQKE

As dvd correctly stated, Evaluate all of the various torque needs.

Here are the torque needs:

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!