US Patent 8342371 Caulking gun with a radially expanding pressure disk

The caulking gun comprises a cartridge holder (12) for accommodating a cartridge (25). For pressing out the substance contained in the cartridge (25), use is made of a piston (30) which is advanced by a pressure disk (16). The pressure disk (16) can be radially expanded under the influence of the advancement force and thus will press by a spreading edge (49) against the side wall (31) of the piston (30). In this manner, the piston in the region of its side wall (31) is tightly pressed against the cartridge wall. Leakage of substance past the piston (30) is prevented.