A steel constituting a chisel according to the present invention includes: 0.40-0.45% by mass of carbon, 0.50-0.80% by mass of silicon, 1.00-1.30% by mass of manganese, 0.001-0.005% by mass of sulfur, 2.90-3.80% by mass of chromium, and 0.20-0.40% by mass of molybdenum, with a balance consisting of iron and an unavoidable impurity, the steel has an ideal critical diameter DI defined by Equation (1) of 600 or more:
DI=7.Math.(% C).sup.1/2.Math.(1+0.64.Math.% Si).Math.(1+4.1.Math.% Mn).Math.(1+2.83.Math.% P).Math.(1−0.62.Math.% S).Math.(1+2.33.Math.% Cr).Math.(1+3.14.Math.% Mo)  (1).

A steel constituting a chisel according to the present invention includes: 0.40-0.45% by mass of carbon, 0.50-0.80% by mass of silicon, 1.00-1.30% by mass of manganese, 0.001-0.005% by mass of sulfur, 2.90-3.80% by mass of chromium, and 0.20-0.40% by mass of molybdenum, with a balance consisting of iron and an unavoidable impurity, the steel has an ideal critical diameter DI defined by Equation (1) of 600 or more:
DI=7.Math.(% C).sup.1/2.Math.(1+0.64.Math.% Si).Math.(1+4.1.Math.% Mn).Math.(1+2.83.Math.% P).Math.(1−0.62.Math.% S).Math.(1+2.33.Math.% Cr).Math.(1+3.14.Math.% Mo)  (1).

A fluid pressure hitting device comprises a piston inserted in a cylinder, a chisel, and a first, second, and third chambers. The chisel is fitted in the cylinder such that a part of the chisel projects from one axial end of the cylinder and is configured to further project from that axial end due to being hit by the piston as the piston slides toward the one axial end. The first through third chambers are partitioned by an inner peripheral surface of the cylinder and an outer peripheral surface of the piston. The first through third chambers are arranged in the axial direction in order fluid the one axial end to another axial end of the cylinder. A flow path is configured to supply fluid from a fluid supply portion when the piston hits the chisel, to the first chamber.

A fluid pressure hitting device comprises a piston inserted in a cylinder, a chisel, and a first, second, and third chambers. The chisel is fitted in the cylinder such that a part of the chisel projects from one axial end of the cylinder and is configured to further project from that axial end due to being hit by the piston as the piston slides toward the one axial end. The first through third chambers are partitioned by an inner peripheral surface of the cylinder and an outer peripheral surface of the piston. The first through third chambers are arranged in the axial direction in order fluid the one axial end to another axial end of the cylinder. A flow path is configured to supply fluid from a fluid supply portion when the piston hits the chisel, to the first chamber.

A concrete anchor capable of resisting large loads while requiring minimal embedment depth. The system includes a concrete structure including a cylindrical opening in the concrete surface thereof. The system also uses an anchor which includes a sleeve and a plug. The sleeve includes at least two legs extending toward a first end of the sleeve. The plug includes an increasing diameter portion disposed toward a first end of the plug. The plug includes a locking opening. After installation, legs of the sleeve extend radially outward past the wall and the increasing diameter portion prevents inward movement of the legs to lock the sleeve and the plug in turn in the concrete cylindrical opening. Furthermore, dynamic loading on the plug via the locking opening when the anchor is in use generates a dynamic radially outward force on the legs to secure the anchor in the concrete hole.

A concrete anchor capable of resisting large loads while requiring minimal embedment depth. The system includes a concrete structure including a cylindrical opening in the concrete surface thereof. The system also uses an anchor which includes a sleeve and a plug. The sleeve includes at least two legs extending toward a first end of the sleeve. The plug includes an increasing diameter portion disposed toward a first end of the plug. The plug includes a locking opening. After installation, legs of the sleeve extend radially outward past the wall and the increasing diameter portion prevents inward movement of the legs to lock the sleeve and the plug in turn in the concrete cylindrical opening. Furthermore, dynamic loading on the plug via the locking opening when the anchor is in use generates a dynamic radially outward force on the legs to secure the anchor in the concrete hole.

The present disclosure generally relates to quick change attachments for a pneumatic percussive tool. The attachments convert a pneumatic percussive tool, such as an air impact tool with proximal attachment, which has a “pushing” force, into a pneumatic percussive tool having a “pulling” force. Once attached to the pneumatic percussive tool, the attachments also provide a quick change feature for allowing “pulling” tools to be simply and easily removed and replaced.

A hand-held power tool includes an electric motor, a tool unit, and at least one operating unit. A motor switching unit is configured to sense a contact-pressure characteristic between the tool unit and the operating unit, and configured to switch the electric motor at least partially in dependence on the contact-pressure characteristic.

A hand-held power tool includes an electric motor, a tool unit, and at least one operating unit. A motor switching unit is configured to sense a contact-pressure characteristic between the tool unit and the operating unit, and configured to switch the electric motor at least partially in dependence on the contact-pressure characteristic.

An impact tool head is provided and configured to be disposed on a front end of an impact tool. The impact tool head includes: a rod body and a flange radially protruding from the rod body. The flange includes an inclined surface facing toward the front end and an outermost peripheral edge. A contact position is defined as a position where the inclined surface contact with at least one projection of the impact tool. Wherein each of the at least one projection is a ball member, and as viewed in the axial direction, a ratio of a distance between the contact position and the outermost peripheral edge to a radius of the at least one projection is between 0.1 and 0.6.