the drill cuttings out from underneath the bit face 19 a the function of the hammer is effective due to the fact that the compressed air flows directly through the bore 9 of the piston 10 with no deviation into the lower chamber 11 and causes the piston 10 to reciprocate faster thereby releasing more energy to the bit 19 in this embodiment of the invention the bit 19 has openings 18 extending transversely through the wall of the bit 19 into a blind bore 19 b the bore 19 b extends from the bit face 19 a through vents 20 operatively described the down the hole drill assembly 1 has compressed air entering the hammer via inlet 2 through the backhead 3 the flow of the compressed air opens check valve 4 down against its spring bias 4 a and the air flows through check valve ports 5 down the air distributor 6 and out of ports 7 pin 8 is disengaged from bore 9 of piston 10 the air flows down the piston bore 9 to pressurize lower chamber 11 the pressure acts on surface area 12 to lift the piston 10 to start its upward stroke during the upward stroke pin 8 enters bore 9 to shut off the airflow to chamber 11 the piston 10 continues in its upward stroke and shoulder 13 of the piston 10 passes ports 14 in the inner sleeve 15 the expanding air in lower chamber 11 exhausts through ports 14 down cutout 16 past the inner end of the bit 19 through ports 17 of the inner sleeve 15 through opening 18 into the.