Abstract: An improved rotary drilling head assembly comprising a main housing having an axial bore therethrough; a stripper assembly disposed within the housing axial bore; and a stripper support assembly rotatingly supporting the stripper assembly. The stripper support assembly is removably attachable to the main housing and comprises an inner skirt member which is configured to extend about and to be supported on an exterior support surface of the main housing; an outer bearing housing configured to extend about and to be bearingly interconnected to the inner skirt member; a stripper clamp assembly clamping the stripper assembly to the outer bearing housing; and a clamping assembly removably attaching the inner skirt member to the exterior support surface such that the entire stripper support assembly of the drilling head assembly is removable from the housing as a unitary assembly by disengaging the clamping assembly.