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The objective of this program was to evaluate the feasibility of a very high overrunning speed one-way clutch for rotor-craft applications. The high speed capability would allow placing the one-way clutch function at the turbine output shaft, that is, the input of the rotorcraft's transmission. The low drive torque present at this location would allow design of a relatively light one-way clutch. During the course of this program, two Mechanical Diode (MD) type overrunning clutches for high speeds were designed. One of the designs was implemented as a set of prototype clutches for high speed overrun testing. A high speed test stand was designed, assembled and qualified for performing overrunning and engagement tests at speeds up to 20,000 rpm. MD overrunning clutches were tested at moderate speed, up to 10,000 rpm and substantial thermal problems associated with oil shear were encountered. The MD design was modified, the modified parts were tested, and by program end, clutches were tested in excess of 20,000 rpm without excessive lubricant temperatures. Some correctable wear was observed and remains as a clutch characteristic which needs further improvement. A load cycle tester with a special, long, sample section was designed, built and then prototype clutches were fatigue tested to verify that the clutch design was suitable for carrying the specified power levels.

The objective of this program was to evaluate the feasibility of a very high overrunning speed one-way clutch for rotorcraft applications. The high speed capability would allow placing the one-way clutch function at the turbine output shaft, that is, the input of the rotorcraft's transmission. The low drive torque present at this location would allow design of a relatively light one-way clutch. During the course of this program, two Mechanical Diode (MD) type overrunning clutches for high speeds were designed. One of the designs was implemented as a set of prototype clutches for high speed overrun testing. A high speed test stand was designed, assembled and qualified for performing overrunning and engagement tests at speeds up to 20,000 rpm. MD overrunning clutches were tested at moderate speed, up to 10,000 rpm and substantial thermal problems associated with oil shear were encountered. The MD design was modified, the modified parts were tested, and by program end, clutches were tested in excess of 20,000 rpm without excessive lubricant temperatures. Some correctable wear was observed and remains as a clutch characteristic which needs further improvement. A load cycle tester with a special, long, sample section was designed, built and then prototype clutches were fatigue tested to verify that the clutch design was suitable for carrying the specified power levels.