By Matt Bamford, Tyler Coffey and Johannah Nelson, The Timken Company
Edited by Mike Santora
While inconspicuous, couplings have long been essential for facilitating the transfer of power within machines and equipment. Gear couplings, a type of flexible coupling, are particularly popular in industrial applications where they transmit high torque loads and tolerate moderate misalignment. Despite widespread use, however, gear couplings are not suited to certain operating conditions where extreme torque is encountered, where properly lubricating parts is a problem, or where routine maintenance and repair are anything but.
Recently, a European steelmaker was in search of a solution to avoid a coupling failure. In a water cooler, the gear coupling connecting the motor to the fan failed prematurely on three occasions, each resulting in three days of lost production from disassembling nearby machinery to replace the gear. Each instance cost the company 120,000 British pounds.
Close analysis revealed gear tooth damage to the failed hub. Such wear is easy to spot with regular inspection, but the considerable tear-down time required meant mill maintenance workers were not changing worn connections with regularity―opting instead to run the couplings to end of life. The solution was an elastomeric coupling that could transmit more torque and required minimal maintenance because there is no metal-to-metal contact, meaning no lubrication is needed.
Unlike the incumbent coupling, the elastomeric alternative uses only one spare part―a urethane insert that can be replaced in a matter of minutes. This simple operation requires the mill to remove only a few bolts, not disassemble the surrounding driving equipment. The insert both negates the issue of gear tooth wear and can be replaced quickly without removing the hubs. And in the event of failure due to excessive torque, the couplings are designed to shear to prevent damage to adjacent machinery when abnormal loads are present.
In another instance, an international energy provider had a similar concern. The ability to inspect gear couplings heavily integrated into power transfer systems was difficult. Routine examination was so impractical it was interfering with the company’s protocols for equipment monitoring. It took two full days to change out the couplings while costs mounted and unease grew about how difficult it was to monitor the health of assets accurately and on an ongoing basis.
An elastomeric coupling was again proposed―where it once took two days to inspect couplings, now roughly 30 minutes is required. As needed, the energy provider can replace the urethane inserts quickly and easily, with the inserts making up only a fraction of a coupling’s total cost. The new couplings can also accept shaft misalignment up to two degrees for performance on par with standard gear-style connections.
As a result, maintenance-related downtime has been reduced, and the company can more closely adhere to its established procedures for regular equipment and component inspection.
Are You Using the Right Coupling?
Gear couplings will continue to be compelling options in many applications. As the examples above illustrate, however, there are times when embracing a newer coupling technology could result in more optimized operations and efficiencies. While a gear coupling failure can result in replacement costs and potential damage to other system components, this is not the only way in which using a less-than-ideal coupling could cost a company. Often, added maintenance expenses and an inability to monitor coupling condition are even bigger problems.
No one solution is perfect for every application, so your best approach for finding the right couplings (or components in general) is always to engage with experts familiar with your application. Quick-Flex elastomeric couplings are available in many bore types and cover/insert configurations, and they are designed to replace virtually all coupling styles in high and low torque applications—you may be surprised to discover how closely they fit your needs.
For information on when you should select a custom coupling, click here.