Four-bar Coupler Curve and Centrode Atlas
This website provides a comprehensive atlas of curves traced by coupler points of four-bar linkages. In the field of Kinematics within Mechanical Engineering, an atlas of coupler curves of four-bar linkages has long been, and continues to be, an effective design tool. The four-bar mechanism is a class of mechanical linkage in which four links are pinned together to form a closed loop in order to perform some useful motion. Such mechanisms are widely used in applications such as automobile hoods and windshield wipers. The coupler in such a mechanism is the link which is not pinned to the ground. Its complex motion can be used for applications like advancing film in movie projectors.
Because the shapes of paths created by couplers is so diverse, they have been compiled into this atlas of curves produced from mechanisms of various dimensions. A similar atlas (with different format) was published by Hrones and Nelson has been out of print since 1951.
The centrodes are two curves which in rolling contact would produce the same motion as the coupler.
The link to the atlas itself is below. For the best experience, I highly recommend that the reader scan the "How to" link.
- How to use and interpret the Coupler Curve and Centrode Atlas
- Coupler Curve Atlas
- Laboratory Problem for Kinematics Students
Send comments or suggestions to thompson@cedarville.edu
The images contained at this site are copywrited 1999 by Thomas Thompson. Permission to copy or download a small number of the images for educational purposes is granted.
This resource was developed under a grant from the Cedarnet Faculty Incentive Program at Cedarville University. This support and the assistance of Mark Mazelin in implementing the javascript is gratefully acknowledged.
Dr. Thomas Thompson | School of Engineering and Computer Science