CENTA Couplings has launched a new design to reliably dampen the increased torsional vibrations from Stage V diesel engines. With its flexibility, the CENTAFLEX-TIR dual-stage torsional roller coupling helps these efficient, downsized engines achieve the lowest idling speeds, allowing end users and original equipment manufacturers (OEMs) to reduce fuel consumption and CO2 emissions in operation.
Coupling challenges for Stage V engines
Stage V is an EU emissions standard applying to non-road mobile machinery with spark or compression ignition engines. Diesel engines built to this specification are more efficient, power-dense, and produce less CO2 and NOx emissions. This is possible thanks to downsizing and delivering peak torques at lower rotations per minute (rpm).
However, smaller, power-dense engines operating at reduced rpm create increased torsional vibrations, especially at idle, which must be dampened to ensure the reliability of powertrain ancillaries such as gearboxes, pumps, and generators. Most flexible couplings are too dynamically rigid for Stage V applications, forcing the engine to run at higher idle speeds to prevent overload, protect equipment, and safeguard uptime. While increasing rpm reduces vibration, it negates the inherent efficiency benefits of Stage V designs.
Flexible for new off-highway equipment
CENTA, a leading brand of Regal Rexnord, has designed the CENTAFLEX-TIR to dampen high torsional vibrations, allowing Stage V engines to run at the lowest idling speeds – saving fuel and reducing emissions. The coupling can also accommodate high torques from electric drives. Consequently, this unique solution offers reliable torque transmission for the next generation of agricultural, construction, mobile crane, marine, quarry, and genset equipment.
Two rows of flexible rubber rollers deliver the coupling’s excellent dampening characteristics. Developed from the proven CENTAFLEX-R, the TIR is twice as flexible and offers an 80% improvement in thermal load capacity at higher alternating torques compared to its predecessor. A corresponding 80% increase in permissible power loss ensures that it effectively absorbs vibration, preventing coupling overload and alternating torque spikes in the powertrain.
Real-world benefits for operations and design
The potential emissions reductions and fuel savings that can be achieved using the CENTAFLEX-TIR were demonstrated during a recent project with a mobile crane OEM. A crane spent 60% of its operating time at idle, and the lower engine rpms supported by the coupling unlocked a fuel saving of 0.9 liters per hour and an annual CO2 reduction of 1.86 tonnes. Furthermore, the fuel cost saving offered an accelerated return on investment (ROI).
Beyond lowering fleet emissions and maximizing the potential of Stage V engine performance, OEMs using the CENTAFLEX-TIR needn’t over-specify power transmission components to withstand increased vibration. Instead, OEMs can downsize ancillaries, optimizing packaging and reducing equipment footprint. As well as a design benefit, this decreases procurement costs too.
The CENTAFLEX-TIR is now available in standard sizes with torque capacities ranging from 2.4 to 10 kNm, with support up to 15 kNm planned. This makes it highly suitable for the off-highway and genset markets, as well as small to medium marine applications. Custom flange connections and hubs are also available to meet varying OEM interfaces. With the advent of Stage V and the Stage VI design process well underway, the CENTAFLEX-TIR is a coupling ready for the current and future transmission requirements of modern diesel engines and electric drives.
Regal Rexnord
www.regalrexnord.com