Compliant Centrifugal Clutch

Summary

This Floating-Opposing-Arm (FOA) Centrifugal Clutch, developed by the BYU CMR lab, utilizes compliant mechanism technology to produce a high performance clutch with only two components. The clutch shoes are fabricated from a single piece of material and the flexible segments connecting the shoes eliminate the need for springs. The two parts of the FOA clutch can be seen below.

What is a centrifugal clutch?

A clutch that uses centrifugal force to engage two concentric shafts.

How does it work?

The torque is transmitted from the central drive hub through the floating clutch shoes to the outer drum. Since centrifugal clutches rely on centrifugal force to actuate, there is increased engagement and friction between the shafts at greater speeds. Likewise, as the drive hub slows down, the floating clutch shoe retracts and disengages from the outer drum.

https://www.youtube.com/watch?v=qANs9G38rzA

Advantages:

• low part count
• easy clutch assembly and replacement
• symmetry that allows for use in either rotational direction
• higher torque than non-aggressive shoes
• smoother start than aggressive shoes
• low probability of self-locking
• adaptable to a variety of materials and loads

Applications

This FOA clutch (originally milled out of steel components) was designed to work in a chain saw. The clutch replaced the original 4 piece clutch while allowing for a reduction in part count and assembly. The FOA centrifugal clutch has also been used in weed wackers, which are usually equipped with two 1/8" thick s-clutches. A single FOA clutch 1/8" thick replaced the two s-clutches. This device shows potential for other lawn and garden equipment as well

Learn More

This design was developed by the Compliant Mechanisms Research Group (CMR) from Brigham Young University (BYU). Follow us at @byucmr on Instagram or visit the BYU Compliant Mechanisms Research (CMR) website to learn more about compliant mechanisms.

Technical Information

For in-depth technical information, see the following publications: 

Crane, N.B., Howell, L.L., Weight, B.L., and Magleby, S.P., “Compliant Floating-Opposing-Arm (FOA) Centrifugal Clutch,” Journal of Mechanical Design, Trans. ASME, Vol. 126, No. 1, pp. 169-177, 2004. 

To learn more about compliant mechanisms in general, see the BYU Compliant Mechanisms Research (CMR) website or these books: Compliant Mechanisms, Handbook of Compliant Mechanisms 

Intellectual Property

The downloadable 3D print files provided here may be used, modified, and enjoyed for noncommercial use. To license this technology for commercial applications, contact:

BYU Technology Transfer Office

3760 Harold B. Lee Library

Brigham Young University

Provo, UT 84602

Phone: (801) 422-6266 

https://techtransfer.byu.edu/contact 

Patent Information

Compliant Clutch
By Howell, L.L. , Crane, N.B.
U.S. Patent No. 6,736,249
May 2004