Patent ID: 9669531
Date: 2017-06-06
CPC Classifications: B25D

Claim:
1. A hammer drill comprising: a body; a cylinder mounted within the body; a motor mounted within the body having an output spindle; a tool holder mounted on the body, the tool holder being capable of holding a cutting tool; a hammer mechanism comprising: characterized in that the air replenishment mechanism is capable of being adjusted so that it refreshes the air spring during different time periods within the hammer cycle during normal use and/or it allows different the volumes of air allows into or out of the air spring during the refreshment time periods, wherein the air replacement mechanism comprises a bleed hole formed through the wall of the cylinder and a valve connected to the bleed hole which, during the hammer cycle, selectively opens and closes the air bleed hole to allow air to pass through it during certain time periods within the hammer cycle and/or controls the volume of air passing through the bleed hole when it is open.