×
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.

# Bearing stress on a rectangular shape on shaft coupling

## Bearing stress on a rectangular shape on shaft coupling

(OP)
Hello,
I have a shaft under torque,
this shaft is coupled by a rectangular connection to transmit the rotation.
Witch is the maximum bearing stress on the surface in contact in the coupling?

we have:
a= long side
b= short side
L= lenght of connection

I'm drawing a sample for better understanding
Thank you
Replies continue below

### RE: Bearing stress on a rectangular shape on shaft coupling

Fwiw I don't think I can help but that never stopped me from providing thoughts before!

I don't see a drawing yet. How does this clamp to or attach to the cylindrical shaft? Or if there is a transition that will need explanation.

Is there a flexible element in the coupling? What speed will it operate at? It strikes me that square cross-section coupling has a resistance to bending in a given stationary direction which will vary as the coupling rotates.... resulting in oscillating reaction loads and vibration.

### RE: Bearing stress on a rectangular shape on shaft coupling

Are you (the OP) describing a rectangular-section key?

### RE: Bearing stress on a rectangular shape on shaft coupling

There is a big stress concentration at the very small radius where the square section joins the circular section. This is most likely your failure point.

### RE: Bearing stress on a rectangular shape on shaft coupling

On six-sided drives ( like a wrench on a hex head cap screw) at times the contact at the corners has received a great deal of attention. Your square drive may have similar loading.
In addition to the transition mentioned by dvd.

example "Flank drive" as probably originated by Snap-On.

https://photos.smugmug.com/MotoIQ/Tech/Sarah-QA/i-...

https://www.transtime-tools.com/data_pics/0001%20(...

https://www.datamp.org/patents/displayPatent.php?p...

As always, if the load is low or the service life is short, you can get away with practically anything.

#### 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.

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!