Portable pneumatic percussive tool

A portable pneumatic percussive tool comprising:

• a cylinder;
• a hammer accommodated in said cylinder and adapted to reciprocate under the action of compressed air and to impart blows to a working implement received in the front end portion of said cylinder;
• an air-distribution means arranged on the rear end face of said cylinder, said means being communicated during the operation of said tool with a compressed air source and adapted to distribute the compressed air provenient from the source;
• a housing mounted on the rear end part of said cylinder and fixed thereto, said housing being adapted to fix said air-distribution means to said cylinder;
• a handle mounted on said housing and axially movable within certain limits along the outer surface of said housing, said handle being adapted to control said tool and to communicate said air-distribution means with the compressed air source in the manner known per se during the movement of the handle forwardly along the housing into the operative position;
• a shock absorber disposed between said housing and said handle, said shock absorber being adapted to return said handle into the rearmost idle position and to lower vibration of said handle;
• said working implement being provided at its rear end part with a shoulder adapted to fix the position of said working implement relative to the cylinder;
• a sleeve composed of a plurality of longitudinally extending parts located on the front end part of said cylinder and embracing said working implement, the outer surface of the sleeve being tapered to converge in the direction toward said working implement, said sleeve being adapted to fix said working implement relative to said cylinder;
• a differential spring, the end of the spring, which has a greater diameter, being of a cylindrical shape and wound about the front end part of said cylinder, while the end of the spring, which has a smaller diameter, being tapered and being urged against said tapered surface of said sleeve in the direction toward the rear end of said cylinder so as to urge said sleeve with its rear end face against the front end face of the cylinder and with the inner surface against the outer surface of said working implement, whereby said sleeve together with said spring form a resilient coupling between said cylinder and said working implement, said coupling allowing said working implement to move forward relative to the cylinder at the instant of blow, with working implement being jammed in the material being demolished, due to an additional expansion of said spring, while after the delivery of a blow said coupling contributing to the cylinder movement forwardly toward the working implement due to the contraction of the expanded spring, thereby lowering vibration of the cylinder in the direction toward the operator and reducing the thrust force to be exerted upon the handle.