This　paper　investigates　meshing　characteristics　of　the　toroidal　drive　with　different　roller　shapes,　examines　the　effect　on　the　characteristics　from　roller　shapes　and　produces　a　comprehensive　comparative　study.　Based　on　the　coordinate　transformation,　the　paper　introduces　the　generic　models　of　meshing　characteristics　and　characterizes　the　meshing　to　introduce　both　undercutting　and　meshing　limit　curves.　The　paper　further　develops　meshing　functions　and　their　derivatives　with　respect　to　each　drive　type　with　a　different　roller　shape.　This　leads　to　a　comprehensive　examination　of　each　meshing　characteristics　against　each　drive　type　of　a　roller　shape.　The　comparative　study　focuses　on　the　effect　of　contact　curves,　tooth　profile,　undercutting,　meshing　limit　curves　and　the　induced　normal　curvature.　This　helps　develop　the　tooth　profile　of　the　sun-worm,　characterize　undercutting　and　meshing　limit　curves　with　different　roller　shapes　and　identify　the　roller　shape　with　the　least　induced　normal　curvature.　The　study　is　then　extended　to　contact　stress　comparison　and　to　verifying　the　least　contact　stress　of　the　roller　type.　This　naturally　leads　to　an　examination　of　manufacturability　with　respect　to　different　roller　types.　(c)　2005　Elsevier　Ltd.　All　rights　reserved.