The new Lo-Rez `’Series Spring” steel spring couplings feature a double row coupling with the two spring rows are arranged in series. The torque is carried from one spring row to the second through an intermediate transfer plate (shown in blue). The resulting overall torsional stiffness of the coupling is reduced to one half the single row rating at the same torque. Preliminary series spring coupling selection can be made using the coupling information in the Lo-Rez `Steel-Spring Flexible Couplings Brochure”, online at www.lo-rez.com. For example, an excerpt from the brochure for a standard Lo-Rez Model H coupling is shown below:
The standard “97.5/1.57” coupling highlighted in yellow carries a torque of 11,000 Nm and has a torsional stiffness of 177,000 Nm/rad. The new series arrangement would also carry a torque of 11,000 Nm, however the torsional stiffness is reduced to 88.500 Nm/rad. The axial, radial and angular stiffness are also reduced by half. The transfer plate adds an extra inertia element to torsional vibration models (typically mid-value of the coupling halves), while the cover is longer than the standard. The axial width is slightly more than double the standard single row coupling width.