×
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.

# motor order

## motor order

(OP)
Hello

Somebody could help to understand the motor order?

Thank you so much.

bye

JOE

Quelquun pourrait maider a comprendre l`ordre du moteur.

Merci

Joe
Escola Politécnica

### RE: motor order

If you mean first engine order as related to harmonic vibrations, then it is simply the cyclic frequency of the crankshaft.

For example, something that happens with a frequency w=(engine order 2) has a frequency of 2*engine speed, and thus happens twice for every rotation of the crankshaft.

### RE: motor order

There is a lazy shorthand we use to describe speeds and vibrations throughout the car, based on ivymike's explanation. Typically we use E for crankshaft speed, D for driveshaft speed, and W for wheel speed.  Then the camshaft turns at 0.5E, the pistons cause 2E 4E etc due to short conrods, tyre out of balance causes 1W, diff whine would be at 13D, UJs cause 2D 4D etc. The astute engineer will notice that there is a fixed ratio between these different speeds, in many circumstances.

The rule of thumb on a 4 stroke is that if there is a half in the vibration (eg 3.5E) then it is usually to do with cylinder to cylinder variation in the firing process, or inertial stuff from the valvetrain. Typical causes are flexibility in long shafts causing timing errors or resonances. For instance, the camshaft in an I6 causes 1.5 order in the combustion process, because each cam is effectively delayed as you go down the camshaft away from the gear. The solution in that case is obvious, of course.

Cheers

Greg Locock

### RE: motor order

Thanks Greg and ivymike, thank you very very much.

Best regards from Brazil

bye

#### 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.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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!