High-Speed Shear Spacer Protects Turbomachinery Drives During Major Torque Overloads
Emerson Power Transmission Corporation / Gearing Division
1248 East Second Street
Maysville, KY, 41056
Press release date: December 5, 2013
FLORENCE, KY — The Kop-Flex high-speed shear spacer coupling uses a patented double-tube design, precision machining and bearings, and special metal treatments to help provide predictable shear during torque overloads on turbo drivetrains, allowing safe coast down of systems turning at up to 20,000 rpm. Developed to protect gas-turbine-powered generator drives during electrical faults, the shear spacer is also ideal for drives on compressors, pumps, fans and trains subject to shock torques. The patented shear cartridge uses special bearings between two tubes to maintain concentricity and overall centering after high-speed separation. The double-bearing design, precision grooving, shot peening and a corrosion resistant coating combine to increase fatigue resistance and promote reliable operation over the life of the coupling. The high-speed shear spacers are available in all catalog coupling sizes capable of handling speeds up to 20,000 rpm and millions of inch-pounds (or Newton-meters) of torque.
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.
For more details on the high-speed shear spacer, see www.PowerTransmissionSolutions.com or visit the Kop-Flex site at www.PowerTransmissionSolutions.com/kopflex for an overview of the company's product line.
Emerson (NYSE: EMR), based in St. Louis, Missouri (USA), is a global leader in bringing technology and engineering together to provide innovative solutions for customers in industrial, commercial, and consumer markets around the world. The company is comprised of five business segments: Process Management, Industrial Automation, Network Power, Climate Technologies, and Commercial Residential Solutions. Sales in fiscal 2013 were $24.7 billion. For more information, visit www.Emerson.com.
About Emerson Industrial Automation
Emerson Industrial Automation, a business of Emerson, is a global technology provider that enables productivity, efficiency and quality gains for customers across a spectrum of industries. Our products include alternators, electric motors and drives, electrical distribution devices and mechanical power transmission, fluid automation and ultrasonic joining solutions. Emerson brands include Appleton, ASCO, Branson Ultrasonics, Browning, Control Techniques, Kop-Flex, Leroy-Somer, McGill, Morse, Numatics, O-Z/Gedney, Rollway, SealMaster, SSB Wind Systems and System Plast. For more information, visit www.PowerTransmissionSolutions.com.
For more information, contact:
Corporate Manager, Global Marketing Communications
Emerson Industrial Automation
Power Transmission Solutions
Release No. MCWR13030E