Muffler

A muffler comprising a hollow cylindrical housing having a sidewall and end walls at either end, one end wall having an axial opening and an inlet connection, said one end wall providing an inwardly-facing annular shoulder surrounding the opening, the other end being imperforate, the sidewall of the housing being formed with aperture means, a corepiece having a diameter approximately equal to the inside diameter of the opening and comprising a thin-walled tubular element being formed with outstruck uniformly spaced helical ridges, the ridges having slots along the peaks thereof for a portion of the length of the ridges, the first end of the tubular element butting against the said other end wall of the housing, retaining means associated with the said one end wall of the housing and engaging the second end of the tubular element to urge said element toward the said other end wall, and a body of metal wool compressed in the annular space between the tubular corepiece and the sidewall of the housing, whereby the helical ridges serve to hold the body of the metal wool from moving along said annular space away from the one end of the housing and the slots along the peaks of the ridges distribute the fluid coming through the inlet into the wool.