Uni-directional drive gear and a gear transmission device with the same

A uni-directional drive gear comprising:

• a mounting seat including a first circular body and a second circular body which are attached to and coaxial with each other along an axis, said second circular body having an outer peripheral surface which surrounds the axis, and a plurality of accommodation bores each of which extends from said outer peripheral surface toward the axis to terminate at a bore bottom, two adjacent ones of said accommodation bores being angularly spaced from each other about the axis by a raised portion, said raised portion having a top surface section at said outer peripheral surface, and a driven surface section and a barrier surface section which are respectively disposed at two opposite sides of said top surface section in a rotational direction and which extend toward the axis to engage said bore bottom;
• a plurality of teeth respectively mounted in said accommodation bores, each of said teeth having a tooth top surface section, and leading and trailing surface sections which are respectively disposed at two opposite sides of said tooth top surface section in the rotational direction, said leading surface section facing said driven surface section;
• a plurality of pivot pins each extending in a direction of the axis from said first circular body into a respective one of said accommodation bores such that each of said teeth is pivotably mounted on a respective one of said pivot pins to be turnable between a driving position, where said leading surface section abuts against said driven surface section and said accommodation bore has a retreat space between said trailing surface section and said barrier surface section, and an idle position, where said trailing surface section is moved in said retreat space;
• and
• a plurality of biasing members each disposed to bias a respective one of said teeth to the driving position such that a torque applied to said trailing surface section is transmitted by keeping the respective one of said teeth in the driving position to drive rotation of said uni-directional drive gear in the rotational direction, and such that a torque applied to said leading surface section leads to turning of the respective one of said teeth in the retreat space to the idle position.