This actuator design allows the extension and contraction of turnbuckle assemblies. It can be operated manually or remotely, and is extremely compact. It is ideal for turnbuckles that are hard to reach by conventional tools. The tool assembly design solves the problem of making accurate adjustments to the variable geometry guide vanes without having to remove and reinstall the actuator system back on the engine. The actuator does this easily by adjusting the length of the turnbuckles while they are still attached to the engine.

The Tool Assembly adjusts the length of theturnbuckle while it is still attached to theengine, eliminating the problem of removingand installing the actuator system back onto theengine.
Made out of metal, the actuator has three components: a gear case, a locking mechanism, and a driver bar. It operates by attaching the gear case around the turnbuckle, then securing the gears with the locking mechanism, and finally making adjustments by turning the driver bar. The gear case consists of two gears and a stabilizing arm. The first gear, the ratcheting gear, is used to make adjustments. The second gear, the turnbuckle gear, operates the turnbuckle, and the stabilizing arm secures the gear case in place. The gear rivet nut of the driver bar fits into the adjustment gear. Manually turning the driver bar rotates the adjustment gear, which in turn engages the turnbuckle gear. As the turnbuckle gear rotates, adjustments are made to the turnbuckle. The stabilizing arm prevents the turnbuckle case from rotating when the driver arm is operated, and the arm is securely attached to the turnbuckle assembly.

To prevent gear movement due to vibration, a locking mechanism secures the gears once adjustments are made. Tool operation is straightforward — the driver bar is turned either clockwise or counterclockwise to lengthen or shorten the turnbuckle. The angle of the guide vanes is read out using encoders mounted on the engine. When the desired offset angle is reached, the locking mechanism is engaged, thus securing the length of the turnbuckle. What would originally have taken a day to accomplish is now done in approximately ten minutes, and with greater accuracy, because the turnbuckle is never removed. The effectiveness of this tool is best appreciated when one considers a typical engine, with four or more turnbuckles, where each turnbuckle requires several configurations to make vane readings.

This work was done by Ricky N. Rivera of Glenn Research Center. For more information, download the Technical Support Package (free white paper) at under the Mechanics/Machinery category.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steve Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-18427-1.

NASA Tech Briefs Magazine

This article first appeared in the January, 2010 issue of NASA Tech Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.