Abstract: A planet carrier 100 has a member 110 which is resistant to buckling caused by torsional stress and which increases a torsional stiffness of the planet carrier 100, so that a torsion load is transmitted evenly from the input member 120 into the planet pins 104 without twisting the planet carrier 100.

Abstract: A method of computer aided engineering for designing a rotating machine assembly involves creating within a graphical user interface of a computer system a layout of the rotating machine assembly, and forming a functional model of the rotating machine assembly from the layout. The layout is created by selecting and positioning components for the rotating machine assembly, and then creating associations between them. The functional model is based on one or more of the associations, relative positions of the selected components, properties of the selected components and properties of the associations.