Compliant Overrunning Clutch

Summary

Overrunning clutches, or freewheel clutches, are used in applications which require torque to be transmitted in only one direction. These clutches have traditionally been used in applications such as vehicle transmissions, engine starters, agricultural equipment, helicopters, and bicycles.There are several variations of over-running clutches, but the four main types include the sprag clutch, the roller or ball clutch, the spring clutch, and the ratchet and pawl clutch. This design most resembles the ratchet and pawl clutch, and was produced by the Compliant Mechanisms Research Group at Brigham Young University, under the direction of Dr. Larry Howell.

Printing

The colorful model shown in the images above was printed with purple, blue, and black PLA filament. ABS or other filaments may be used, but PLA demonstrates the function of the clutch very well with the provided dimensions. The clutch teeth were made with an extruded cylinder to resemble a drive shaft and to facilitate functional demonstration.

The white model was cut out of polypropylene using a water jet, then was assembled with screws and an additional square top piece to facilitate functional demonstration.

Water jets, laser cutters, wire EDM, and milling equipment could also be used to produce the compliant overrunning clutch.

Application

Advantages of using a compliant overrunning clutch:
-lower part count than alternative designs
-easy assembly and maintenance
-reduced part wear
-low cost
-simplicity
-less lubrication required

Disadvantages:
-difficult to manufacture due to very thin segments
-requires non-linear analysis methods
-noisy (when clutch teeth are passively rotating past compliant part)

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 publication: 

Roach, G.M., Lyon, S.M., and Howell, L.L., “A Compliant, Overrunning Ratchet and Pawl Clutch with Centrifugal Throw-out,” Proceedings of the 25th Biennial Mechanisms and Robotics Conference, at the 1998 ASME Design Engineering Technical Conferences, Atlanta, Georgia, DETC98/MECH-5819. 

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 Overrunning Clutch with Centrifugal Throw-out
By Roach, G.M. , Howell, L.L.
U.S. Patent No. 6,148,979
November 2000