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feature flexible couplings

New pump coupling reduceseffects of torque, misalignment and unbalance

At last year’s International Pump Users Symposium, Baltimore-based Kop-Flex

®

, a division ofEmerson Power Transmission, introduced a new design of elastomeric coupling featuring dual- flex elements. In this article, Matt McGinnityandJon Mancusodiscuss the design’scharacteristics, and present experimental data comparing its performance to existingelastomeric couplings.

Pump Coupling Reduces Effects of Torque, Misalignment and Unbalance - 15937 I

n 2004, Kop-Flex introduced aunique elastomeric coupling.Trade-named ‘Odyssey’, thispatented new development features dual-flex elements in the form ofurethane diaphragms bonded to eachend of a composite spacer (Figure 1). The dual-flex elastomeric diaphragmelement was designed using the latestengineering technology: finite element analysis (FEA) and 3D CAD. The characteristics required of thisnew pump coupling were definedbased on an industry survey of pumpmanufacturers and pump users, which yielded 16 desirable qualitativecoupling characteristics:1. Good torque capacity compared to OD2. No lubrication 3. Ease of field installation 4. Ease of maintenance5. Ease of field replacement6. High reliability 7.Low weight 8. Good balance quality (meet API610 AGMA Class 9 requirements)9. Low reaction forces on bearings 10. At least five years of life without replacement11. Reserve operating angular misalignment capacity and also parallel offset misalignment capabilities without producingexcessive loads on equipment12. Reasonable axial capacity to accommodate reasonable errors in shaft-to-shaft errors for applications using interference hubs 13. Operate in ambient temperature of at least 65.5°C (150°F)14. Predictable mode of failure that does not cause excessive damage to equipment15. Low axial stiffness 16. Some torsional damping.The dual-flex elastomeric elementprovides not only high angular misalignment capacity, but also highoffset misalignment capacity, withlow reaction moments and forces transferred to the connected equipment. The spacer is made fromlightweight composite material,which makes the dual-flex concept feasible for an elastomeric typecoupling, and, because of its lowweight, it reduces the unbalance

a) c) b) d)

Figure 1. The Odyssey dual-flex elastomeric diaphragm coupling. Figure 2. Various types of pump couplings: (a) gear coupling, (b) disc coupling, (c) gridcoupling, and (d) dual-flex diaphragm elastomeric coupling. 34
0262 1762/05 © 2005 Elsevier Ltd. All rights reserved WORLD PUMPS
May 2005