Power hand tool

Abstract

A power hand tool includes a housing containing a motor, a speed changing gear set coupled to the power output end of the motor, a transmission mechanism coupled to the speed changing gear set and partially extending out of the housing for operation by the user to selectively shift the speed changing gear set to one of a series of gearshift positions thereof, a set of index signs marked on the transmission mechanism corresponding to the series of gearshift positions and alternatively moved to a sighthole in the housing subject to the gearshift position of the speed changing gear set, and a light emitting device mounted in the housing adjacent to the sighthole for illuminating one index sign of the transmission mechanism that is in alignment with the sighthole.

1 . A power hand tool comprising: 
 a housing having a through hole and a sighthole;    a motor fixedly mounted inside said housing, said motor having a power output end for outputting a rotary driving force at a predetermined revolving speed;    a multi-step speed changer having a speed changing gear set coupled to the power output end of said motor, and a transmission mechanism coupled to said speed changing gear set and partially extending out of said through hole of said housing for operation by the user to selectively shift said speed changing gear set to one of a series of gearshift positions thereof, said transmission mechanism having a series of index signs corresponding to said gearshift positions, said index signs being alternatively moved to said sighthole subject to the gearshift positions of said speed changing gear set; and    an indicator having a light emitting device mounted in said housing adjacent to said sighthole for illuminating one of said index signs of said transmission mechanism that is moved to said sighthole.    
   
   
       2 . The power hand tool as claimed in  claim 1 , further comprising a battery pack mounted inside said housing and electrically coupled to said motor and said light emitting device to provide the necessary working electricity to said motor and said light emitting device.  
   
   
       3 . The power hand tool as claimed in  claim 1 , wherein said indicator further comprises a light-transmissible covering mounted in said sighthole for magnifying the image of the index sign of said transmission mechanism that is moved to said sighthole.  
   
   
       4 . The power hand tool as claimed in  claim 3 , wherein said light-transmissible covering is a convex lens.  
   
   
       5 . The power hand tool as claimed in  claim 1 , wherein said transmission mechanism comprises a gearshift control bar axially slidably mounted inside said housing, said gearshift control bar having an operating knob disposed at one side thereof and extending out of said housing through said through hole for operation by the user to move said gearshift control bar axially forwards or backwards, and a transmission shaft coupled between said speed changing gear set and said gearshift control bar and movable by said gearshift control bar to change the gearshift position of said speed changing gear set; wherein said index signs are marked on said gearshift control bar and alternatively shifted with said gearshift control bar to said sighthole.  
   
   
       6 . The power hand tool as claimed in  claim 1 , wherein said light emitting device is a light emitting diode.