Abstract: A four-wheel drive unit for a toy vehicle, comprising a windup spring drive mechanism including a first axle, a gear mechanism having a second axle and a link shaft which rotatably connects the first axle to the second axle via link gears so that the gear mechanism may pivot around the axis of the link shaft with reference to the drive mechanism, and the first and the second axles may be rotated in the same direction.

Abstract: An improved spring-wound prime mover provides a housing cavity that can automatically fix one end of a spring upon insertion. The gear train includes individual gears that automatically provide a first gear ratio for storing energy and a second gear ratio for releasing energy. The prime mover is assembled with a friction fitting arrangement to simplify manufacturing.

Abstract: An improved spring wound prime mover capable of use with toys is provided. A plastic resin housing member comprises a pair of housing shells having complementary locking pawls and keeper members to permit a snap together assembly. The housing member further supports a spring member that can be selectively connected to a gear train assembly having a first and second gear ratio. The first gear ratio includes gears with a higher degree of mechanical strength than those engaged in the second gear ratio whereby a durable gear transmission is provided that can run smooth for driving the vehicle.