Abstract: A pneumatic percussion machine such as a drill having a piston reciprocating in a casing, chambers formed in the casing at or towards the ends of the piston, the arrangement permitting compressed air to be supplied alternatively to the chambers, the compressed air to the one chamber being supplied through a projecting member located co-axially in the casing, and over which the piston reciprocates, and the piston and compressed air from the other chamber being exhausted from such chamber between the wall of the casing and a stepped portion of the piston and then through the piston to atmosphere. Provision is made for the piston to move to a position, in an inoperative condition of the machine, in which both chambers are open to the atmosphere.

Abstract: A pneumatic impact tool comprising a housing, an open ended cylinder inserted therein and a hammer piston reciprocably guided within the cylinder. In the forward end of the cylinder there is received the shank of a chisel onto which the hammer piston imparts impacts. The piston is a differential piston having its big end facing the chisel and forming around its rear, small diameter neck a rear annular, constantly pressurized chamber which continuously communicates with the pressure air inlet through a pulsator chamber. The forward cylinder chamber, enclosed between the chisel shank and the piston front area, is intermittently pressurized through an internal passage of the piston, which passage is periodically connected to the pressure air inlet by means of valve openings in the piston neck.

Abstract: A ram device has a drop hammer connected to the piston of a lifting cylinder which is connected by means of short and wide ducts to a control apparatus for admitting compressed air into the cylinder and for discharging the air from the cylinder beneath the piston, control apparatus directly communicating with the ambient air so as to allow a rapid escape of the air through large air vent ports from beneath the piston. In particular this control apparatus is directly mounted on the cylinder, or is included in an extension of this cylinder.