An adaptor is disclosed for connecting a generator to a prime mover. The adaptor comprises two separable parts. By providing an adaptor comprising two separable parts, it may be possible for one part to be removed in order to allow access to moving parts which would otherwise be inaccessible. This may simplify the process of servicing moving parts such as a coupling or bearings, without requiring the generator and the prime mover to be moved apart. A coupling with a radially removable elastomeric component is also disclosed.