[R+W] Made with safety in mind – aerospace applications

R+W Antriebselemente GmbH

Made with safety in mind

Testing transmissions used in aerospace applications is serious business. Prod

uction engineers need to guarantee performance across a wide range of extreme loading conditions – and failure is not an option.
Recently R+W was involved in developing a coupling system between a drive motor and a production test stand for just this purpose. The combination of heavy loads, high value of the equipment being tested, and uncertainty regarding what can happen in a high-powered testing environment necessitated multiple safety features be built into the best coupling possible for the job.

Technical specifications for the coupling:

  • Overall length: 1010mm
  • Disengagement torque: 25,000 Nm
  • Rotational speed: 2100 rpm
  • Removable center section with anti-flail features

In addition to delivering a continuous torque at speed while putting the transmission under test through its paces, this coupling needs to be able to safely disconnect the driveline at an overload torque of 25,000 Nm in case of a component lockup or operator error. The overload safety requirement makes it a perfect fit for the R+W ST-series of safety element torque limiters, designed to disengage with speed and accuracy in the event of an overload and allow for a simple reset after release.
In order to span the ~1m distance required by the machine layout, flexible disc packs from the R+W LP-series were chosen as the misalignment compensating elements. The key advantage in this case is that disc packs are stiff in shear, and each individual flexible element is designed to accommodate a single pivot rather than a traditional parallel misalignment. With two disc packs spaced apart on either end of the intermediate spacer, the resulting double flex system nearly eliminates misalignment loading while also holding the intermediate section rigidly on center without whipping.

In the interest of easier handling, the coupling is also configured with a drop-out center section. Once the bolts are removed from the outer flanges adjacent to the disc packs, they can be used as draw screws to cause the disc packs to flex inward and disengage the centering pilots for easy removal of the center cartridge without the need to disturb the end hubs.
This makes life quite a bit simpler when it comes to assembling the machine and for maintaining it down the road. Finally, integral safety catches are included in the form of protrusions from the outer hubs through the center holes of the disc packs to prevent the intermediate spacer section from being thrown in the event of disc pack rupture.

While this should never happen based on the current application parameters, safety is the top priority in this kind of high stakes testing environment.

September 23, 2020|Tags: , , , |