Stromag, part of Altra Industrial Motion, has designed a hybrid Periflex CR (PCR) shaft coupling solution for a customer’s dredging vessel platform. The system features a 1,200 hp diesel engine that drives a custom-designed, eight-pad gearbox with primary output to a two-speed clutch that drives the system’s main pump, as well as hydraulic pump pads to operate a crane and auxiliaries, explained Stromag.
To compound the challenge, the space envelope available for the coupling was severely constrained, and the chosen solution would need to fit into the supplier’s existing gearbox bell housing, the company said.
The modified PCR coupling developed for the application includes a rubber element from a similar Stromag model PCS coupling and a bolt-on adaptor hub with a splined bore. The flexible ring used in this coupling is key to the design, since it transmits torque while absorbing torsional impacts, explained Stromag.
“The coupling arrangement between the engine and gearbox was critical to the performance and reliability of the application,” said Stromag’s managing director Dr Robert Rank. “In use, the system experienced high levels of torsional vibration; if not properly managed, this vibration could accelerate wear, and potentially lead to early failure of key components,” he explained, adding that the coupling technology developed was capable of handling the high power, torque, and vibration levels involved while also protecting other mechanical elements from excessive vibrations and shock loads.
The Stromag Periflex shaft coupling is a highly flexible rubber-fabric coupling, particularly suitable for connecting two shafts in diesel engine and electric drives.
“To ensure that its proposed solution would be able to handle the expected operating conditions, the Stromag team conducted extensive torsional vibration analysis on a model of the complete transmission system and its nine driven components,” said Dr Rank.