Patent ID: 6209659
Filing Date: 2001-04-03
Classification: B25D

Abstract:
A hand-held drill, comprising a housing (2); a chuck (6) provided at a front, in a drilling direction, end of the housing (2) for receiving one of a drill or chisel tool (7); a motor a rotary drive (8-15) arranged inside the housing for driving the chuck, together with the one of drill and chisel tool receivable in the chuck; a compressed air-operated hammer mechanism (21) for generating axial blows to be applied to the one of drill and chisel tool; and a compressor driven by the motor for providing of compressed air (17) communicating with the hammer mechanism, the hammer mechanism having a pneumatic cylinder (22) with at least one inlet opening (23) and at least one discharge opening (24), a die member (15) for imparting the axial blows, which are generated by the hammer mechanism, (21), to the one of drill and chisel tool and extending through a front limiting surface (25) of the pneumatic cylinder (22), and a percussion piston (30) displaceable in the pneumatic cylinder (22) upon being impinged by compressed air for intermittently applying axial blows to the die member (15), and a reversing valve for connecting the hammer mechanism (21) with the source of compressed air, integrated in the percussion piston (30), and having a plurality of recesses and bores (46-52) alternatively operationally connectable with the at least one inlet opening (23) and the at least one discharge opening (24) of the pneumatic cylinder (22) for feeding the compressed air into the pneumatic cylinder (22) and for discharging the compressed air therefrom, wherein the reversing valve has opposite ends which extend, in forward and rearward stroke positions of the percussion piston (30), beyond a rebound surface (33) and a rear surface (34) of the percussion piston (30), respectively, and engage the front limiting surface (25) and a rear limiting surface (26) of the pneumatic cylinder (22), respectively.