Massey Ferguson Professional Series offer added external protection via driveGuard. The DriveGuard is designed to shear before internal components are damaged protection the Shaft and Modules from Shock Loads when encountering field hazards.
Here you can see the top of each module and the inner drive hub is connected to the outer drive hub with a bearing in-between. The bearing does not move until the driveGuard is sheared, retaining the Top Hat to the Drive Hub. No need to go hunting for the Top Hat if you encounter an obstruction. Just replace the driveGuard and back to cutting you go.
This image shows the driveGuard prior to Top Hat being assembled on the Module Drive Shaft.
Here is Video Showing how this system works and how to replace the driveGaurd when an obstruction is encountered.