The high-speed shear spacer is an improvement over standard shear spacers and shear pins, which can create issues when used above 3,600 rpm due to balancing issues and fretting potential when using pins. “Standard shear spacers are not engineered to survive the unbalance forces that develop when turbo drivetrains hit a torque overload at high speeds (3,600-20,000 rpm),” said Joe Corcoran, Manager of Global Services and Training for Emerson’s Kop-Flex coupling business. “Coast down from high speed can be unpredictable with a standard shear spacer, and more damage can result.
“This design takes the standard shear spacer concept to a whole new level of technology,” said Corcoran. “We start with a comprehensive understanding of the material properties of each unique unit, and use metal treatments, testing, precision machining and special bearings to create a custom shear spacer for each application.”
During manufacture, the spacer’s parts are heat-treated with a sample from the same metal batch. Samples are tested to determine exact shear strength, and test data is used to design and machine a precision shear groove on the spacer. Polishing the surface minimizes stress concentrations, and shot peening compresses the surface layer to minimize chances of crack growth. A special corrosion resistant coating is also available to further stabilize the surface.
“Our tests show we’re able to predict the static shearing force within 1.5% on a finished unit, and we have successfully run these cartridges at high speeds after separation to validate they can provide ample time for equipment coast down,” added Corcoran.
Many units have been in the field for years and are operating with great success.
Emerson Industrial Automation, Power Transmission Solutions
www.PowerTransmissionSolutions.com