An impact tool which transmits an impact force to a tool bit supported by a casing includes: a cylinder which is attached to the casing and has an opening on one end side thereof to which the tool bit is inserted; an intermediate element which is provided in an inside of the cylinder so as to be able to move straight, has a projection projecting in a radial direction so as to regulate a range of the straight movement, and transmits the impact force to the tool bit; and passages and which communicate a space in an inside of the cylinder at a position nearer to the tool bit than the projection with the outside of the cylinder and penetrate through the cylinder in the radial direction.

A hammer drive mechanism is provided for converting rotary drive from a motor to reciprocatory movement of an impact member of a hammer drill. The mechanism comprises a rotatable plate adapted to be rotated by the motor, an input drive member associated with the rotatable plate in an eccentric position with respect to the axis of rotation of the rotatable plate, an output drive member associated with the impact member, and a crank shaft having a respective driver adjacent each of its ends. Each driver engages with, and is complementary to a respective one of the drive members. At least one end portion of the crank shaft comprises a lubricating aperture which opens into the adjacent driver to provide a lubrication path to the engaging surfaces of the drivers and the drive members.

The present invention discloses an electric chisel capable of being matched with a domestic electric drill to be used. The electric chisel comprises an electric drill, a casing, a push rod and chisel head mechanism and a groove cam mechanism. The top of the casing is provided with an oil hole, and a rubber plug is arranged on the oil hole to be used for preventing dust; the two ends of the groove cam mechanism are provided with a first bearing and a second bearing respectively, and a first groove and a second groove are formed below the first bearing and the second bearing respectively and positioned in the inner wall of the casing. The groove cam mechanism is provided with a groove, and the push rod and chisel head mechanism is connected with the groove cam mechanism and performs reciprocating motion up and down in the groove of the groove cam mechanism. During the use, the whole electric chisel is installed on the domestic electric drill, and when the groove cam mechanism is driven by the electric drill to rotate, the push rod and chisel head mechanism performs liner reciprocating motion. The electric chisel is simple in structure, small in size, portable and convenient to operate and can quickly chisel floors or wall tiles.

A main shaft of a power tool is sequentially divided into an impact section, a penetrative section and an output section, wherein the impact section is formed with an impact portion and has a curved recess defined therein, and the penetrative section is adapted to extend through a front portion of the power tool. The main shaft has a linear tunnel defined therein and extending therethrough. The linear tunnel has two opposite ends respectively defined as an inlet and an outlet, wherein the inlet is situated in the output section and the outlet is adapted to correspond to an impact block of an impact device of the power tool. An axis of the linear tunnel is formed an included angle with an axis of the main shaft.