Patent ID: 7140450

Claim:
A percussion tool, comprising: a housing defining a passageway having first and second ends and which further mounts a tool bit which has a proximal and a distal end, and wherein air is received within the passageway; a hammer which is reciprocally moveably mounted within the passageway as defined by the housing, and having a main body defining a first internal passageway, and which is positioned in substantially coaxial alignment relative to the tool bit, and wherein air is received within the first internal passageway, and wherein the main body further has a first end which is operable to repeatedly strike the tool bit, and an opposite second end defining an end wall which has an aperture formed therein and which mounts a seal; a reciprocally moveable piston received in the first internal passageway of the reciprocally moveable hammer, and wherein the air which is received within the first internal passageway can periodically pass by the piston, and be exchanged with the air which is received in the passageway defined by the housing; a piston rod having a first end which is mounted on the piston, and an opposite second end, and wherein the piston rod reciprocally moves, at least in part, through the aperture formed in the side wall, and is sealably engaged by the seal; a motor coupled to the second end of the reciprocally moveable piston rod and which is operable to move the piston along a defined path of travel within the first internal passageway, and wherein the movement of the piston causes the first end of the hammer to reciprocally move and repeatedly strike the proximal end of the rotatable tool bit, while simultaneously causing the air which is received within the passageway defined by the housing to be compressed; an air passageway which fluidly couples the first end of the passageway defined by the housing with the second end of the passageway, and wherein air within the air passageway can move from the first end of the housing to the second end of the housing to equalize air pressure within the housing; and a valve disposed in fluid metering relation relative to the air passageway.