A three-gear position type transmission mechanism for a remote control toy car comprising:
- a tubular transmission shaft, said tubular transmission shaft having a polygonal segment in a circularly tubular shaft body thereof;
- a transmission gear set mounted on said tubular transmission shaft, said transmission gear set comprising a first transmission gear wheel mounted on a two-way axle bearing at said tubular transmission shaft for two-way rotary motion, said first transmission gear wheel comprising an external gear and an internal gear, a second transmission gear wheel mounted on a two-way axle bearing at said tubular transmission shaft for two-way rotary motion, said second transmission gear wheel comprising an external gear, an internal gear, and a clutch adapted for engaging the internal gear of said first transmission gear wheel for enabling said first transmission gear wheel to be rotated with said second transmission gear wheel, a third transmission gear wheel mounted on said tubular transmission shaft for one-way rotary motion with said tubular transmission shaft, said third transmission gear wheel comprising a polygonal center hole coupled to the polygonal segment of said tubular transmission shaft, an external gear, and a clutch adapted for engaging the internal gear of said second transmission gear wheel for enabling said second transmission gear wheel to be rotated with said third transmission gear wheel;
- a driven gear wheel fixedly fastened to said first transmission gear wheel;
- and
- an idle gear set, said gear set comprising a center shaft supported on two-way axle bearings, a first idle gear fixedly mounted on said center shaft meshed with the external gear of said first transmission gear wheel, a second idle gear mounted on a one-way axle bearing at said center shaft and meshed with the external gear of said second transmission gear wheel, and a third idle gear mounted on a one-way axle bearing at said center shaft and meshed with the external gear of said third transmission gear wheel;
- wherein when said driven gear wheel rotated by an external drive unit to rotate said first transmission gear wheel, said third idle gear is driven to rotate said third transmission gear wheel and said tubular transmission shaft at a low speed;
- the clutch of said third transmission gear wheel is forced outwards by a centrifugal force into engagement with the internal gear of said second transmission gear wheel when the revolving speed of said third transmission gear wheel surpassed a predetermined level, thereby causing said second transmission gear wheel and said second idle gear to be synchronously rotated with said tubular transmission shaft and said third transmission gear wheel at a middle speed;
- the clutch of said second transmission gear wheel is forced outwards by a centrifugal force into engagement with the internal gear of said first transmission gear wheel when the revolving speed of said second transmission gear wheel surpassed a predetermined level, thereby causing said first transmission gear wheel, said second transmission gear wheel, said third transmission gear wheel, said first idle gear, said second idle gear, said third idle gear, and said tubular transmission shaft to be rotated at a high speed.