Patent ID: 6095256
Filing Date: 2000-08-01
Classification: B44B

Abstract:
A hand-held pneumatic impact tool for use in delicate hand working operations for use with a supply of pressurized air, comprising:a housing having two ends and containing a longitudinal cylindrical cavity,an annular shoulder included within said longitudinal cylindrical cavity,a two-step piston accommodated and moveable within said longitudinal cylindrical cavity,a tool tip supported at one end of said housing,said two-step piston dividing said longitudinal cylindrical cavity with said annular shoulder into:a head chamber, defined by the end face of the smaller step of said two-step piston and facing in the direction of said tool tip, the end face of said annular shoulder and facing in the direction of said tool tip, the end of said longitudinal cylindrical cavity facing away from said tool tip;a central chamber defined by the end face of the larger step of said two-step piston and facing in the direction of said tool tip, the end face of said annular shoulder and facing in the direction away from said tool tip;a rear chamber defined by the end face of the larger step of said two-step piston and facing in the direction away from said tool tip, the end of said longitudinal cylindrical cavity facing towards said tool tip,a longitudinal passage provided in said two-step piston and communicating permanently with said rear chamber,at least one piston port in said two-step piston, communicating permanently with said longitudinal passage and with the side surface of the smaller step of said two-step piston,an intake port through said housing, communicating permanently with said central chamber for connection to said pressurized air source,at least one exhaust port through said housing, communicating permanently with said head chamber and with the atmosphere,said rear chamber communicating with the atmosphere when said two-step piston is so disposed relative to said housing so that said at least one piston port of said two-step piston is aligned with said head chamber communicating with the atmosphere through said at least one exhaust port,said rear chamber communicating with said pressurized air source when said two-step piston is so disposed relative to said housing so that said at least one piston port is aligned with said central chamber communicating with said pressurized air source through said intake port,an oscillation means by which said two-step piston will oscillate under the action of said supply of pressurized air, anda foot-operated air flow regulating mechanism connected between said supply of pressurized air and said housing wherein said air flow regulating mechanism, includes:a valve for regulating air flow to said housing, anda base on which a foot pedal is mounted for pivotal movement on a horizontal axis,wherein said foot pedal is adjustable and influencing said valve in which air flow regulating ranges from zero to potential flow from said supply of pressurized air source.