Wheel and pinion assembly with friction drive/slip coupling for a timepiece

An improved reduction gear assembly with friction drive/slip coupling for a timpiece movement, comprising:

• a metal pinion member having a toothed pinion and a coaxial stem extending from an abutment surface on said pinion, said stem including (1) a cylindrical portion, (2) a frustum portion tapering from a smaller diameter less than that of said cylindrical portion to a larger diameter, and (3) a terminating tapered end portion;
• and
• a plastic wheel member having a toothed wheel and first and second coaxial journals extending from opposite sides of said wheel, said journals adapted to rotatably support said wheel and pinion assembly, said first and second journals together defining a central passage having a constricted section therein with a diameter slightly less than that of said larger diameter of said frustum portion on said metal pinion member,
• said pinion stem cylindrical portion rotatably disposed in said central passage with one of said journals abutting said toothed pinion abutment surface and said frustum disposed in said constricted passage with a snap fit, whereby a friction drive/slip coupling is provided between said metal frustum portion of said metal pinion member and said constricted passage of said plastic wheel member.