Abstract: A depth stop for a drilling tool comprises a rod 12 mounted on the tool body for sliding movement in directions parallel to the drilling movement, and a locking lever 15 pivotally mounted about a pivot boss 16 which projects at a substantially right angle to but is offset from the rod. The rod, extends through an aperture in the upper part 18 of the lever which aperture provides a radical clearance for the rod, and a spring 19 biases the lever so as to bring a peripheral edge or opposite peripheral edges of an aperture through the lever into frictional engagement with the rod and the biasing direction is the same as the direction in which the rod tends to move when it comes into abutment with a workpiece. The rod can be released by manually swivelling the lever against the spring force. The rod 12 may have a knurled surface 14 so as to provide substantially a mechanical lock with the co-operating peripheral edge of the lever aperture.

Abstract: In a rotary hammer drill in which a tool is driven in rotation by rotating the cylinder housing a driver piston and a striker, the hammering effect is rendered inoperative by providing in the well of the barrel an aperture which is axially positioned so as to vent the space between the driver and striker to the atmosphere. A sleeve is mounted on the external surface of the barrel and is axially movable to blank off the aperture or to place it in communication with the ambient atmosphere.

Abstract: A portable electric hammer drill incorporates an electric motor 12 disposed close to the handle 13 of the tool and with its axis of rotation at right angles to the axis of rotation of the drill bit holder 10, and a gear 15 on the motor shaft meshes with a first pinion 16 driving the holder in rotation. A second pinion 25 meshes with the first pinion 16 and drives the driving piston 30 of the mechanism for transmitting impacts to the holder. The axes of rotation of the holder 10, the first and second pinions and the gear 15 ;are coplanar, and the first and second pinions are on diametrically opposite sides of the said gear, the first pinion being nearer the handle. This arrangement enables the motor to be placed nearer the handle than if the first pinion were in direct mesh with the said gear, and thus improves the balance of the tool. The arrangement permits the diameters of the first and second pinions to be selected independently of each other.