SPEED MECHANISM FOR SCREW DRIVER

摘要

A screw driver includes a body having a ratchet unit and a first transmission rod extends through the ratchet unit. The first transmission rod has a ratchet gear and a switch member is connected to the ratchet unit to control the operation status of the ratchet gear. The first transmission rod has a tube connected to a first end thereof and a non-circular connection portion is connected to a second end of the first transmission rod. A handle is connected to the body and has a toothed ring located therein. The toothed ring is engaged with a planet gear unit which is engaged with a sun gear mounted to a second transmission rod which has an accommodating portion. The accommodating portion is engaged with the connection portion. The individual first and second transmission rods do not generate resistance when the screw driver operates the objects at high speed.