firstfloor & bearfoil,
To see the shaft couplings in perhaps more detail, go to this site and click on the Trent 500 icon. Granted it is a Trent 500 and not a Trent 900, but I bet not much has changed relative to the general layout/architecture.
Portfolio of Technical Illustrations, Aviation Cutaway Drawings (Ghosted Drawings) & Technical Art. Info Graphics from Flightline Arts, UK.
Hope this is helpful.