Abstract: Point-line meshing gear is a new kind of gear transmission. The selections of parameters between point-line meshing gear and involuted gear are different while designed. The closed picture of involuted gear can not be applied to that of the point-line meshing gear. The closed picture of point-line meshing gear relates to the number of teeth z1, z2 and the tool parameters, but it doesn't relate to center distance a and modul- us mn. The big gear's coefficient factor x2 and helix angle b are chiefly decided by the closed picture, and other parameters are accordingly decided then. It illustrates the meanings of curves of the closed picture. It also illustrates that by designing different x2 and β the bears with different tooth profile, meshing angles, whole depths as well as the characters of meshing etc will be got. It also mentions the characteristics of point-line meshing gear and the abnormal graphs as well as their characteristics while choosing different tool’s parameters with the sameness z1 and z2.

Key words: Closed picture, Parameter, Point-line gear