Hammer drill with drive and percussion elements accommodated in a

Abstract

A hammer drill comprises a housing with a cylinder in the housing defining a cylindrical piston chamber and an air chamber located around at least a portion of the piston chamber sealed against the ambient atmosphere and against adjacent components of the housing. The housing defines a tool-receiving chamber aligned with and communicating with the piston chamber and a percussion body is movable in a piston chamber against a tool positioned in the tool-receiving chamber. The piston is reciprocated through a crank drive by an electric motor within the housing toward and away from a percussion body. The cylinder defines a pneumatic buffer zone between the piston and the percussion body so that air which is displaced by the movement of the piston provides a coupling and buffing fluid between the piston and the percussion body. The cylinder is provided with a first air passage opening which communicates with the air chamber and the buffer zone, and it is spaced from the piston when the piston is in a forward dead-center position. The housing has a collar-receiving recess and a radially extending annular collar-shaped shoulder is defined on the cylinder and it extends into the recess. The collar is provided with air passages therethrough, and it determines the spatial position of the cylinder in the housing. The housing and the cylinder are in form-locked interengagement.