A down-the-hole hammer drill bit assembly includes a foot valve and a drill component having respective abutment regions in the form of cooperating lugs and shoulders that may be engaged by rotation of the valve relative to the drill bit component to allow the lugs and shoulders to overlap radially to lock the valve at the drill component. The assembly is advantageous to allow coupling and decoupling on-site without the need for specific swaging or hydraulic/pneumatic assembly tools.