Abstract: A down-the-hole percussive hammer includes a casing, a drill bit attached to a lower end of the casing, and a reciprocable hammer for impacting against the drill bit. A top sub attached to an upper end of the casing includes a central passage for conducting operating air for actuating the piston. A feed tube is attached to the top sub and extends along a center axis thereof. The feed tube includes vertically spaced outlet and re-entry ports sealed from one another by a seal disposed inside of the feed tube. The outlet and re-entry ports communicate with a chamber formed in the central passage. A check valve is disposed at an upper end of the feed tube. The check valve includes an elastic sleeve arranged to overlie the outlet port and to be elastically biased away from the outlet port by pressurized operating air, whereupon the operating air passes out of the feed tube through the outlet port and then back into the feed tube through the re-entry port.