Hammer drill with drive and percussion elements accommodated in a cylinder

A hammer drill comprising a housing;

• a cylinder received in said housing and defining a cylindrical piston chamber;
• means defining an air chamber around at least a portion of said piston chamber sealed against the ambient atmosphere and against the adjacent component parts of said housing;
• said housing defining a tool-receiving chamber aligned and communicating with said piston chamber;
• a percussion body movable in said piston chamber against a tool in said tool-receiving chamber;
• a motor-driven piston reciprocable in said piston chamber relative to said percussion body;
• said cylinder also defining a pneumatic buffer zone between said piston and said percussion body, whereby air in said buffer zone provides a coupling and buffing fluid between said piston and said percussion body;
• a first air passage opening defined in said cylinder and interconnecting said air chamber and the interior of said cylinder in said buffer zone, said first air passage being spaced from said piston when said piston is in a forward dead-center position;
• said housing having a collar-receiving recess;
• a radially outwardly extending collar-shaped shoulder formed on said cylinder and extending across said air chamber and into the recess in said housing, said shoulder having air passages extending therethrough, and said shoulder determining the spatial position of said cylinder in said housing;
• and means form-lockably interengaging said housing and said cylinder to hold said cylinder in said housing against rotation.