EMBANKMENT HAMMER

An overburden drilling equipment for drilling a hole. The equipment comprises a down-the-hole hammer (11) for rock drilling, comprising a cylinder (13), a piston (20) reciprocating in the cylinder due to pressurized water being directed alternately to the upper and lower ends of the piston to effect its reciprocation in the cylinder. Each downward stroke inflicting an impact blow upon an anvil portion (17) of a drill bit (12) extending upwardly within the lower portion of the cylinder. A drill chuck (21) is mounted at a lower end of the cylinder to receive the drill bit. A generally cylindrical casing shoe ( 14) adapted for attachment with a casing (15) and rotatably connected to the drill bit to be longitudinally advanced thereby during a drilling operation. The drill chuck comprising at least one key (30) defines the largest radius of the drill chuck. The casing comprises a diametrically reduced portion (32) which has at least one keyway therein. The key and the diametrically reduced portion (32) retain the hammer in relation to the drill bit.