Stromag, a brand of Altra Industrial Motion Corp., has provided the coupling solution for a customer’s dredging vessel platform. The coupling is for a 1,200 hp diesel engine, which drives an 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 cranes and auxiliaries.
Stromag said the coupling arrangement between the engine and gearbox was critical to the performance and reliability of the application. The coupling technology high power capability, and needed to handle the torque and vibration levels involved, while also protecting other mechanical elements from excessive vibrations and shock loads. To compound the challenge, the space envelope available for the coupling was severely constrained.
After reviewing the customer’s requirements in detail, the Stromag engineering team designed a hybrid Periflex CR (PCR) shaft coupling. The modified PCR coupling used 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 design transmits torque while absorbing torsional impacts.
The Stromag Periflex shaft coupling is a flexible rubber-fabric coupling, particularly suitable for connecting two shafts in diesel engine and electric drives. Due to the special design of the shaft tyre, the Periflex shaft coupling is able to absorb large displacements in every direction with low restoring forces, without noticeable wear and tear. As standard, the tyre can be radially mounted and dismantled using a separation joint without moving the connected machines. The Periflex shaft coupling transmits the torque free of backlash. It is suitable for absorbing torque shocks and dampens vibrations. The standard Periflex CR series covers the torque range from 480 to 14,800 Nm.
To ensure that its proposed solution would be able to handle the expected operating conditions, the Stromag team conducted extensive torsional vibration analysis (TVA) on a model of the complete transmission system and its nine driven components.