The worm drive efficiency was improved in order to require the higher precision,the hourglass worm equation of the complete eveloping contact line was utilized,the classical meshing theory was combined besides the parameters of the tool generatrix was fitted, the novel meshing transmission mode of the planar enveloping end face meshing engagement toroidal wrom was constructed on the former basis. The tooth-profile helical line of this worm was obtained by the drawing contact line with MATLAB; the three dimentional graphics was plotted and the kinematic simulation was analysed by using software of CREO as well.According to this reaserch:the planar enveloping end face meshing engagement toroidal worm,this newfashioned driving mode could increase the effective meshing tooth number through controlling its parameters to a certain extent,meanwhile its working length was shortened;and the gyration radius was magnified,the radial size of this worm volume was largened caused by the increscent gyration radius, however the large center distance transmission was achieved without increasing the worm gear size;also the structure of these same model retarders was more compact.
