This　paper　develops　a　mathematic　model　for　the　dynamic　characteristics　analysis　of　a　toroidal　drive.　This　model　allows　the　analysis　of　a　toroidal　transmission　with　any　number　of　the　planet　worm　gears　distributed　around　the　sun　worm.　The　independence　spherical　roller　and　periodic　gear　mesh　flexibilities　are　considered　in　the　mathematical　modelling　through　nonlinear　relative　gear　mesh　displacement　functions.　A　dynamic　load　sharing　factor　is　defined　and　the　effects　of　design　parameters,　machining　and　assembly　variations　are　quantified.